提交 4be66376 编写于 作者: H HelloCrease

Merge branch 'master' of https://gitee.com/HelloCrease/docs

要显示的变更太多。

To preserve performance only 1000 of 1000+ files are displayed.
...@@ -17,11 +17,36 @@ ...@@ -17,11 +17,36 @@
- ExtensionAbility Component - ExtensionAbility Component
- [ExtensionAbility Component Overview](extensionability-overview.md) - [ExtensionAbility Component Overview](extensionability-overview.md)
- [ServiceExtensionAbility](serviceextensionability.md) - [ServiceExtensionAbility](serviceextensionability.md)
- [FormExtensionAbility (Widget)](widget-development-stage.md) - [DataShareExtensionAbility (for System Applications Only)](datashareextensionability.md)
- [AccessibilityExtensionAbility](accessibilityextensionability.md) - [AccessibilityExtensionAbility](accessibilityextensionability.md)
- [EnterpriseAdminExtensionAbility](enterprise-extensionAbility.md) - [EnterpriseAdminExtensionAbility](enterprise-extensionAbility.md)
- [InputMethodExtensionAbility](inputmethodextentionability.md) - [InputMethodExtensionAbility](inputmethodextentionability.md)
- [WindowExtensionAbility](windowextensionability.md) - [WindowExtensionAbility](windowextensionability.md)
- Service Widget Development in Stage Model
- [Service Widget Overview](service-widget-overview.md)
- Developing an ArkTS Widget
- [ArkTS Widget Working Principles](arkts-ui-widget-working-principles.md)
- [ArkTS Widget Related Modules](arkts-ui-widget-modules.md)
- ArkTS Widget Development
- [Creating an ArkTS Widget](arkts-ui-widget-creation.md)
- [Configuring Widget Configuration Files](arkts-ui-widget-configuration.md)
- [Widget Lifecycle Management](arkts-ui-widget-lifecycle.md)
- Widget Page Development
- [Widget Page Capability Overview](arkts-ui-widget-page-overview.md)
- [Using Animations in the Widget](arkts-ui-widget-page-animation.md)
- [Applying Custom Drawing in the Widget](arkts-ui-widget-page-custom-drawing.md)
- Widget Event Development
- [Widget Event Capability Overview](arkts-ui-widget-event-overview.md)
- [Updating Widget Content Through FormExtensionAbility](arkts-ui-widget-event-formextensionability.md)
- [Updating Widget Content Through UIAbility](arkts-ui-widget-event-uiability.md)
- [Redirecting to a Specified Page Through the Router Event](arkts-ui-widget-event-router.md)
- Widget Data Interaction
- [Widget Data Interaction Overview](arkts-ui-widget-interaction-overview.md)
- [Configuring a Widget to Update Periodically](arkts-ui-widget-update-by-time.md)
- [Updating Local and Online Images in the Widget](arkts-ui-widget-image-update.md)
- [Updating Widget Content by State](arkts-ui-widget-update-by-status.md)
- [Updating Widget Content by Widget Host (for System Applications Only)](arkts-ui-widget-content-update.md)
- [Developing a JS Widget](js-ui-widget-development.md)
- [AbilityStage Component Container](abilitystage.md) - [AbilityStage Component Container](abilitystage.md)
- [Context](application-context-stage.md) - [Context](application-context-stage.md)
- Want - Want
...@@ -47,6 +72,7 @@ ...@@ -47,6 +72,7 @@
- [Subscribing to Common Events in Static Mode (for System Applications Only)](common-event-static-subscription.md) - [Subscribing to Common Events in Static Mode (for System Applications Only)](common-event-static-subscription.md)
- [Unsubscribing from Common Events](common-event-unsubscription.md) - [Unsubscribing from Common Events](common-event-unsubscription.md)
- [Publishing Common Events](common-event-publish.md) - [Publishing Common Events](common-event-publish.md)
- [Removing Sticky Common Events](common-event-remove-sticky.md)
- [Background Services](background-services.md) - [Background Services](background-services.md)
- Inter-Thread Communication - Inter-Thread Communication
- [Thread Model](thread-model-stage.md) - [Thread Model](thread-model-stage.md)
......
...@@ -12,10 +12,13 @@ The **AccessibilityExtensionAbility** module provides accessibility extension ca ...@@ -12,10 +12,13 @@ The **AccessibilityExtensionAbility** module provides accessibility extension ca
This document is organized as follows: This document is organized as follows:
- [Creating an AccessibilityExtAbility File](#creating-an-accessibility-extension-service) - [AccessibilityExtensionAbility Development](#accessibilityextensionability-development)
- [Processing an Accessibility Event](#processing-an-accessibility-event) - [Creating an Accessibility Extension Service](#creating-an-accessibility-extension-service)
- [Declaring Capabilities of Accessibility Extension Services](#declaring-capabilities-of-accessibility-extension-services) - [Creating a Project](#creating-a-project)
- [Enabling a Custom Accessibility Extension Service](#enabling-a-custom-accessibility-extension-service) - [Creating an AccessibilityExtAbility File](#creating-an-accessibilityextability-file)
- [Processing an Accessibility Event](#processing-an-accessibility-event)
- [Declaring Capabilities of Accessibility Extension Services](#declaring-capabilities-of-accessibility-extension-services)
- [Enabling a Custom Accessibility Extension Service](#enabling-a-custom-accessibility-extension-service)
## Creating an Accessibility Extension Service ## Creating an Accessibility Extension Service
...@@ -79,13 +82,13 @@ You can also process physical key events in the accessibility extension service. ...@@ -79,13 +82,13 @@ You can also process physical key events in the accessibility extension service.
## Declaring Capabilities of Accessibility Extension Services ## Declaring Capabilities of Accessibility Extension Services
After developing the custom logic for an accessibility extension service, you must add the configuration information of the service to the corresponding module-level **module.json5** file in the project directory. In the file, the **srcEntrance** tag indicates the path to the accessibility extension service. Make sure the value of the **type** tag is fixed at **accessibility**. Otherwise, the connection to the service will fail. After developing the custom logic for an accessibility extension service, you must add the configuration information of the service to the corresponding module-level **module.json5** file in the project directory. In the file, the **srcEntry** tag indicates the path to the accessibility extension service. Make sure the value of the **type** tag is fixed at **accessibility**. Otherwise, the connection to the service will fail.
```json ```json
"extensionAbilities": [ "extensionAbilities": [
{ {
"name": "AccessibilityExtAbility", "name": "AccessibilityExtAbility",
"srcEntrance": "./ets/AccessibilityExtAbility/AccessibilityExtAbility.ts", "srcEntry": "./ets/AccessibilityExtAbility/AccessibilityExtAbility.ts",
"label": "$string:MainAbility_label", "label": "$string:MainAbility_label",
"description": "$string:MainAbility_desc", "description": "$string:MainAbility_desc",
"type": "accessibility", "type": "accessibility",
......
# Configuring Widget Configuration Files
Widget-related configuration includes **FormExtensionAbility** configuration and widget configuration.
1. Configure FormExtensionAbility information under **extensionAbilities** in the [module.json5 file](../quick-start/module-configuration-file.md). For a FormExtensionAbility, you must specify **metadata**. Specifically, set **name** to **ohos.extension.form** (fixed), and set **resource** to the index of the widget configuration information.
Example configuration:
```json
{
"module": {
...
"extensionAbilities": [
{
"name": "EntryFormAbility",
"srcEntry": "./ets/entryformability/EntryFormAbility.ts",
"label": "$string:EntryFormAbility_label",
"description": "$string:EntryFormAbility_desc",
"type": "form",
"metadata": [
{
"name": "ohos.extension.form",
"resource": "$profile:form_config"
}
]
}
]
}
}
```
2. Configure the widget configuration information. In the **metadata** configuration item of FormExtensionAbility, you can specify the resource index of specific configuration information of the widget. For example, if resource is set to **$profile:form_config**, **form_config.json** in the **resources/base/profile/** directory of the development view is used as the profile configuration file of the widget. The following table describes the internal field structure.
**Table 1** form_config.json file
| Field| Description| Data Type| Default Value Allowed|
| -------- | -------- | -------- | -------- |
| name | Class name of the widget. The value is a string with a maximum of 127 bytes.| String| No|
| description | Description of the widget. The value can be a string or a resource index to descriptions in multiple languages. The value is a string with a maximum of 255 bytes.| String| Yes (initial value: left empty)|
| src | Full path of the UI code corresponding to the widget. For an ArkTS widget, the full path must contain the widget file name extension, for example, **./ets/widget/pages/WidgetCard.ets**. For a JS widget, the full path does not need to contain the widget file name extension, for example, **./js/widget/pages/WidgetCard**.| String| No|
| uiSyntax | Type of the widget.<br>- **arkts**: ArkTS widget<br>- **hml**: JS widget| String| Yes (initial value: **hml**)|
| window | Window-related configurations.| Object| Yes|
| isDefault | Whether the widget is a default one. Each UIAbility has only one default widget.<br>- **true**: The widget is the default one.<br>- **false**: The widget is not the default one.| Boolean| No|
| colorMode | Color mode of the widget.<br>- **auto**: auto-adaptive color mode<br>- **dark**: dark color mode<br>- **light**: light color mode| String| Yes (initial value: **auto**)|
| supportDimensions | Grid styles supported by the widget.<br>- **1 * 2**: indicates a grid with one row and two columns.<br>- **2 * 2**: indicates a grid with two rows and two columns.<br>- **2 * 4**: indicates a grid with two rows and four columns.<br>- **4 * 4**: indicates a grid with four rows and four columns.| String array| No|
| defaultDimension | Default grid style of the widget. The value must be available in the **supportDimensions** array of the widget.| String| No|
| updateEnabled | Whether the widget can be updated periodically.<br>- **true**: The widget can be updated at a specified interval (**updateDuration**) or at the scheduled time (**scheduledUpdateTime**). **updateDuration** takes precedence over **scheduledUpdateTime**.<br>- **false**: The widget cannot be updated periodically.| Boolean| No|
| scheduledUpdateTime | Scheduled time to update the widget. The value is in 24-hour format and accurate to minute.<br>**NOTE**<br>**updateDuration** takes precedence over **scheduledUpdateTime**. If both are specified, the value specified by **updateDuration** is used.| String| Yes (initial value: The widget cannot be updated periodically.)|
| updateDuration | Interval to update the widget. The value is a natural number, in the unit of 30 minutes.<br>If the value is **0**, this field does not take effect.<br>If the value is a positive integer *N*, the interval is calculated by multiplying *N* and 30 minutes.<br>**NOTE**<br>**updateDuration** takes precedence over **scheduledUpdateTime**. If both are specified, the value specified by **updateDuration** is used.| Number| Yes (initial value: **0**)|
| formConfigAbility | Link to a specific page of the application. The value is a URI.| String| Yes (initial value: left empty)|
| formVisibleNotify | Whether the widget is allowed to use the widget visibility notification.| String| Yes (initial value: left empty)|
| metadata | Metadata of the widget. This field contains the array of the **customizeData** field.| Object| Yes (initial value: left empty)|
Example configuration:
```json
{
"forms": [
{
"name": "widget",
"description": "This is a service widget.",
"src": "./ets/widget/pages/WidgetCard.ets",
"uiSyntax": "arkts",
"window": {
"designWidth": 720,
"autoDesignWidth": true
},
"colorMode": "auto",
"isDefault": true,
"updateEnabled": true,
"scheduledUpdateTime": "10:30",
"updateDuration": 1,
"defaultDimension": "2*2",
"supportDimensions": [
"2*2"
]
}
]
}
```
# Updating Widget Content by Widget Host (for System Applications Only)
Widgets that are updated periodically are subject to the scheduled time or interval settings. To offer more flexible updates, the widget host can provide a button to proactively trigger a widget update. Specifically, the widget host calls the [requestForm](../reference/apis/js-apis-app-form-formHost.md#requestform) API to request a widget update. The system then calls the [onUpdateForm](../reference/apis/js-apis-app-form-formExtensionAbility.md#onupdateform) lifecycle callback in the FormExtensionAbility of the widget provider. In the callback, the [updateForm](../reference/apis/js-apis-app-form-formProvider.md#updateform) API can be used to update the widget content. For details about the **onUpdateForm** lifecycle callback, see [Updating Widget Content Through FormExtensionAbility](arkts-ui-widget-event-formextensionability.md).
```ts
import formHost from '@ohos.app.form.formHost';
@Entry()
@Component
struct WidgetCard {
formId = ...; // Widget ID
build() {
Button (`Update Widget`)
.type(ButtonType.Capsule)
.width('50%')
.height(50)
.onClick(() => {
console.info('FormAbility update form click');
// formId is the ID of the widget to be updated.
formHost.requestForm(this.formId.toString()).then(() => {
console.info('Succeeded in requestForming.');
});
})
...
}
}
```
# Creating an ArkTS Widget
To create an ArkTS widget in an existing application project, perform the following steps:
1. Create a widget.
![WidgetProjectCreate1](figures/WidgetProjectCreate1.png)
2. Select a widget template based on the actual service scenario.
![WidgetProjectCreate2](figures/WidgetProjectCreate2.png)
3. Set **Language** to **ArkTS** and click **Finish**.
![WidgetProjectCreate3](figures/WidgetProjectCreate3.png)
After an ArkTS widget is created, the following widget-related files are added to the project directory: **EntryFormAbility.ts** (widget lifecycle management file), **WidgetCard.ets** (widget page file), and **form_config.json** (widget configuration file).
![WidgetProjectView](figures/WidgetProjectView.png)
# Updating Widget Content Through FormExtensionAbility
On the widget page, the **postCardAction** API can be used to trigger a message event to the FormExtensionAbility, which then updates the widget content. The following is an example of this widget update mode.
- On the widget page, register the **onClick** event callback of the button and call the **postCardAction** API in the callback to trigger the event to the FormExtensionAbility.
```ts
let storage = new LocalStorage();
@Entry(storage)
@Component
struct WidgetCard {
@LocalStorageProp('title') title: string = 'init';
@LocalStorageProp('detail') detail: string = 'init';
build() {
Column() {
Button ('Update')
.onClick(() => {
postCardAction(this, {
'action': 'message',
'params': {
'msgTest': 'messageEvent'
}
});
})
Text(`${this.title}`)
Text(`${this.detail}`)
}
.width('100%')
.height('100%')
}
}
```
- Call the [updateForm](../reference/apis/js-apis-app-form-formProvider.md#updateform) API to update the widget in the **onFormEvent** callback of the FormExtensionAbility.
```ts
import formBindingData from '@ohos.app.form.formBindingData';
import FormExtensionAbility from '@ohos.app.form.FormExtensionAbility';
import formProvider from '@ohos.app.form.formProvider';
export default class EntryFormAbility extends FormExtensionAbility {
onFormEvent(formId, message) {
// Called when a specified message event defined by the form provider is triggered.
console.info(`FormAbility onEvent, formId = ${formId}, message: ${JSON.stringify(message)}`);
let formData = {
'title':'Title Update Success.', // Matches the widget layout.
'detail':'Detail Update Success.', // Matches the widget layout.
};
let formInfo = formBindingData.createFormBindingData(formData)
formProvider.updateForm(formId, formInfo).then((data) => {
console.info('FormAbility updateForm success.' + JSON.stringify(data));
}).catch((error) => {
console.error('FormAbility updateForm failed: ' + JSON.stringify(error));
})
}
// ...
}
```
The figure below shows the effect.
![WidgetUpdatePage](figures/WidgetUpdatePage.png)
# Widget Event Capability Overview
The ArkTS widget provides the **postCardAction()** API for interaction between the widget internal and the provider application. Currently, this API supports the router, message, and call events and can be called only in the widget.
![WidgetPostCardAction](figures/WidgetPostCardAction.png)
Definition: postCardAction(component: Object, action: Object): void
Parameters:
| Name| Type| Mandatory| Description|
| -------- | -------- | -------- | -------- |
| component | Object | Yes| Instance of the current custom component. Generally, **this** is transferred.|
| action | Object | Yes| Action description. For details, see the following table.|
Description of the action parameter
| **Key** | **Value** | Description|
| -------- | -------- | -------- |
| "action" | string | Action type.<br>- **"router"**: application redirection. If this type of action is triggered, the corresponding UIAbility is displayed. Only the UIAbility of the current application can be displayed.<br>- **"message"**: custom message. If this type of action is triggered, the [onFormEvent()](../reference/apis/js-apis-app-form-formExtensionAbility.md#onformevent) lifecycle callback of the provider FormExtensionAbility is called.<br>- **"call"**: application startup in the background. If this type of action is triggered, the corresponding UIAbility is started but does not run in the foreground. The target application must have the permission to run in the background ([ohos.permission.KEEP_BACKGROUND_RUNNING](../security/permission-list.md#ohospermissionkeep_background_running)).|
| "bundleName" | string | Name of the target bundle when **action** is **"router"** or **"call"**. This parameter is optional.|
| "moduleName" | string | Name of the target module when **action** is **"router"** or **"call"**. This parameter is optional.|
| "abilityName" | string | Name of the target UIAbility when **action** is **"router"** or **"call"**. This parameter is mandatory.|
| "params" | Object | Additional parameters carried in the current action. The value is a key-value pair in JSON format.|
Sample code of the **postCardAction()** API:
```typescript
Button ('Jump')
.width('40%')
.height('20%')
.onClick(() => {
postCardAction(this, {
'action': 'router',
'bundleName': 'com.example.myapplication',
'abilityName': 'EntryAbility',
'params': {
'message': 'testForRouter' // Customize the message to be sent.
}
});
})
```
The following are typical widget development scenarios that can be implemented through widget events:
- [Updating Widget Content Through FormExtensionAbility](arkts-ui-widget-event-formextensionability.md)
- [Updating Widget Content Through UIAbility](arkts-ui-widget-event-uiability.md)
- [Redirecting to a Specified Page Through the Router Event](arkts-ui-widget-event-router.md)
# Redirecting to a Specified Page Through the Router Event
The **router** capability of the **postCardAction** API can be used in a widget to quickly start the widget provider application. An application can provide different buttons through the widget so that users can jump to different pages at the touch of a button. For example, a camera widget provides the buttons that direct the user to respective pages, such as the page for taking a photo and the page for recording a video.
![WidgerCameraCard](figures/WidgerCameraCard.png)
Generally, a button is used to start a page.
- Design two buttons on the widget page. When one of the buttons is clicked, **postCardAction** is called to send a router event to the specified UIAbility, with the content to be transferred defined in the event.
```ts
@Entry
@Component
struct WidgetCard {
build() {
Column() {
Button ('Function A')
.margin('20%')
.onClick(() => {
console.info('Jump to EntryAbility funA');
postCardAction(this, {
'action': 'router',
'abilityName': 'EntryAbility', // Only the UIAbility of the current application is allowed.
'params': {
'targetPage': 'funA' // Process the information in the EntryAbility.
}
});
})
Button ('Function B')
.margin('20%')
.onClick(() => {
console.info('Jump to EntryAbility funB');
postCardAction(this, {
'action': 'router',
'abilityName': 'EntryAbility', // Only the UIAbility of the current application is allowed.
'params': {
'targetPage': 'funB' // Process the information in the EntryAbility.
}
});
})
}
.width('100%')
.height('100%')
}
}
```
- The UIAbility receives the router event and obtains parameters. It then starts the page specified in the received message.
```ts
import UIAbility from '@ohos.app.ability.UIAbility';
import window from '@ohos.window';
let selectPage = "";
let currentWindowStage = null;
export default class CameraAbility extends UIAbility {
// If the UIAbility is started for the first time, the onCreate lifecycle callback is triggered after the router event is received.
onCreate(want, launchParam) {
// Obtain the targetPage parameter passed in the router event.
console.info("onCreate want:" + JSON.stringify(want));
if (want.parameters.params !== undefined) {
let params = JSON.parse(want.parameters.params);
console.info("onCreate router targetPage:" + params.targetPage);
selectPage = params.targetPage;
}
}
// If the UIAbility is running in the background, the onNewWant lifecycle callback is triggered after the router event is received.
onNewWant(want, launchParam) {
console.info("onNewWant want:" + JSON.stringify(want));
if (want.parameters.params !== undefined) {
let params = JSON.parse(want.parameters.params);
console.info("onNewWant router targetPage:" + params.targetPage);
selectPage = params.targetPage;
}
if (currentWindowStage != null) {
this.onWindowStageCreate(currentWindowStage);
}
}
onWindowStageCreate(windowStage: window.WindowStage) {
let targetPage;
// Start the page specified by targetPage.
switch (selectPage) {
case 'funA':
targetPage = 'pages/FunA';
break;
case 'funB':
targetPage = 'pages/FunB';
break;
default:
targetPage = 'pages/Index';
}
if (currentWindowStage === null) {
currentWindowStage = windowStage;
}
windowStage.loadContent(targetPage, (err, data) => {
if (err && err.code) {
console.info('Failed to load the content. Cause: %{public}s', JSON.stringify(err));
return;
}
});
}
};
```
# Updating Widget Content Through UIAbility
On the widget page, the **postCardAction** API can be used to trigger a router or call event to start the UIAbility, which then updates the widget content. The following is an example of this widget update mode.
- On the widget page, register the **onClick** event callback of the button and call the **postCardAction** API in the callback to trigger the event to the FormExtensionAbility.
```ts
let storage = new LocalStorage();
@Entry(storage)
@Component
struct WidgetCard {
@LocalStorageProp('detail') detail: string = 'init';
build() {
Column() {
Button ('Jump')
.margin('20%')
.onClick(() => {
console.info('postCardAction to EntryAbility');
postCardAction(this, {
'action': 'router',
'abilityName': 'EntryAbility', // Only the UIAbility of the current application is allowed.
'params': {
'detail': 'RouterFromCard'
}
});
})
Text(`${this.detail}`).margin('20%')
}
.width('100%')
.height('100%')
}
}
```
- In the **onCreate()** or **onNewWant()** lifecycle callback of the UIAbility, use the input parameter **want** to obtain the ID (**formID**) and other information of the widget, and then call the [updateForm](../reference/apis/js-apis-app-form-formProvider.md#updateform) API to update the widget.
```ts
import UIAbility from '@ohos.app.ability.UIAbility';
import formBindingData from '@ohos.app.form.formBindingData';
import formProvider from '@ohos.app.form.formProvider';
import formInfo from '@ohos.app.form.formInfo';
export default class EntryAbility extends UIAbility {
// If the UIAbility is started for the first time, the onCreate lifecycle callback is triggered after the router event is received.
onCreate(want, launchParam) {
console.info('Want:' + JSON.stringify(want));
if (want.parameters[formInfo.FormParam.IDENTITY_KEY] !== undefined) {
let curFormId = want.parameters[formInfo.FormParam.IDENTITY_KEY];
let message = JSON.parse(want.parameters.params).detail;
console.info(`UpdateForm formId: ${curFormId}, message: ${message}`);
let formData = {
"detail": message +': onCreate UIAbility.', // Matches the widget layout.
};
let formMsg = formBindingData.createFormBindingData(formData)
formProvider.updateForm(curFormId, formMsg).then((data) => {
console.info('updateForm success.' + JSON.stringify(data));
}).catch((error) => {
console.error('updateForm failed:' + JSON.stringify(error));
})
}
}
// If the UIAbility is running in the background, the onNewWant lifecycle callback is triggered after the router event is received.
onNewWant(want, launchParam) {
console.info('onNewWant Want:' + JSON.stringify(want));
if (want.parameters[formInfo.FormParam.IDENTITY_KEY] !== undefined) {
let curFormId = want.parameters[formInfo.FormParam.IDENTITY_KEY];
let message = JSON.parse(want.parameters.params).detail;
console.info(`UpdateForm formId: ${curFormId}, message: ${message}`);
let formData = {
"detail": message +': onNewWant UIAbility.', // Matches the widget layout.
};
let formMsg = formBindingData.createFormBindingData(formData)
formProvider.updateForm(curFormId, formMsg).then((data) => {
console.info('updateForm success.' + JSON.stringify(data));
}).catch((error) => {
console.error('updateForm failed:' + JSON.stringify(error));
})
}
}
...
}
```
# Updating Local and Online Images in the Widget
Generally, local images or online images downloaded from the network need to be displayed on a widget. To obtain local and online images, use the FormExtensionAbility. The following exemplifies how to show local and online images on a widget.
1. Internet access is required for downloading online images. Therefore, you need to apply for the **ohos.permission.INTERNET** permission. For details, see[Declaring Permissions in the Configuration File](../security/accesstoken-guidelines.md).
2. Update local files in the **onAddForm** lifecycle callback of the EntryFormAbility.
```ts
import formBindingData from '@ohos.app.form.formBindingData';
import formProvider from '@ohos.app.form.formProvider';
import FormExtensionAbility from '@ohos.app.form.FormExtensionAbility';
import request from '@ohos.request';
import fs from '@ohos.file.fs';
export default class EntryFormAbility extends FormExtensionAbility {
...
// When the widget is added, a local image is opened and transferred to the widget page for display.
onAddForm(want) {
// Assume that the local image head.PNG is in the tmp directory of the current widget.
let tempDir = this.context.getApplicationContext().tempDir;
// Open the local image and obtain the FD after the image is opened.
let file;
try {
file = fs.openSync(tempDir + '/' + 'head.PNG');
} catch (e) {
console.error(`openSync failed: ${JSON.stringify(e)}`);
}
let formData = {
'text': 'Image: Bear',
'imgName': 'imgBear',
'formImages': {
'imgBear': file.fd
},
'loaded': true
}
// Encapsulate the FD in formData and return it to the widget page.
return formBindingData.createFormBindingData(formData);
}
...
}
```
3. Update online files in the onFormEvent lifecycle callback of the EntryFormAbility.
```ts
import formBindingData from '@ohos.app.form.formBindingData';
import formProvider from '@ohos.app.form.formProvider';
import FormExtensionAbility from '@ohos.app.form.FormExtensionAbility';
import request from '@ohos.request';
import fs from '@ohos.file.fs';
export default class EntryFormAbility extends FormExtensionAbility {
// When the message event is triggered on the widget page, an online image is downloaded and transferred to the widget page for display.
onFormEvent(formId, message) {
let formInfo = formBindingData.createFormBindingData({
'text': 'Updating...'
})
formProvider.updateForm(formId, formInfo)
// Note: The FormExtensionAbility is started when the lifecycle callback is triggered. It can run in the background for only 5 seconds.
// When possible, limit the size of the image to download. If an image cannot be downloaded within 5 seconds, it cannot be updated to the widget page.
let netFile = 'https://xxxx/xxxx.png'; // Specify the URL of the image to download.
let tempDir = this.context.getApplicationContext().tempDir;
let fileName = 'file' + Date.now();
let tmpFile = tempDir + '/' + fileName;
request.downloadFile(this.context, {
url: netFile, filePath: tmpFile, enableMetered: true, enableRoaming: true
}).then((task) => {
task.on('complete', function callback() {
console.info('ArkTSCard download complete:' + tmpFile);
let file;
try {
file = fs.openSync(tmpFile);
} catch (e) {
console.error(`openSync failed: ${JSON.stringify(e)}`);
}
let fileInfo = {};
fileInfo[fileName] = file.fd;
let formData = {
'text': 'Image:' + fileName,
'imgName': fileName,
'formImages': fileInfo,
'loaded': true
};
let formInfo = formBindingData.createFormBindingData(formData)
formProvider.updateForm(formId, formInfo).then((data) => {
console.info('FormAbility updateForm success.' + JSON.stringify(data));
}).catch((error) => {
console.error('FormAbility updateForm failed: ' + JSON.stringify(error));
})
})
task.on('fail', function callBack(err) {
console.info('ArkTSCard download task failed. Cause:' + err);
let formInfo = formBindingData.createFormBindingData({
'text':'Update failed.'
})
formProvider.updateForm(formId, formInfo)
});
}).catch((err) => {
console.error('Failed to request the download. Cause: ' + JSON.stringify(err));
});
}
...
};
```
4. On the widget page, use the **\<Image>** component to display the widget content transferred from the EntryFormAbility.
```ts
let storage = new LocalStorage();
@Entry(storage)
@Component
struct WidgetCard {
@LocalStorageProp('text') text: string = 'Loading...';
@LocalStorageProp('loaded') loaded: boolean = false;
@LocalStorageProp('imgName') imgName: string = 'name';
build() {
Column() {
Text(this.text)
.fontSize('12vp')
.textAlign(TextAlign.Center)
.width('100%')
.height('15%')
Row() {
if (this.loaded) {
Image('memory://' + this.imgName)
.width('50%')
.height('50%')
.margin('5%')
} else {
Image('common/start.PNG')
.width('50%')
.height('50%')
.margin('5%')
}
}.alignItems(VerticalAlign.Center)
.justifyContent(FlexAlign.Center)
Button ('Update')
.height('15%')
.onClick(() => {
postCardAction(this, {
'action': 'message',
'params': {
'info': 'refreshImage'
}
});
})
}
.width('100%').height('100%')
.alignItems(HorizontalAlign.Center)
.padding('5%')
}
}
```
> **NOTE**
> - The **\<Image>** component displays images in the remote memory based on the **memory://** identifier in the input parameter (**memory://fileName**). The **fileName** value must be consistent with the key in the object (**'formImages': {key: fd}**) passed by the EntryFormAbility.
>
> - The **\<Image>** component determines whether to update the image based on whether the input parameter is changed. Therefore, the value of **imgName** passed by the EntryFormAbility each time must be different. If the two values of **imgName** passed consecutively are identical, the image is not updated.
# Widget Data Interaction
The ArkTS widget framework provides the **updateForm()** and **requestForm()** APIs to proactively trigger widget updates.
![WidgetLocalStorageProp](figures/WidgetLocalStorageProp.png)
| API| System Capability| Constraints|
| -------- | -------- | -------- |
| updateForm | No| 1. Invoked by the provider.<br>2. Allows only the widget provider to update its own widgets. It cannot be used to update widgets by other providers.|
| requestForm | Yes| 1. Invoked by the host.<br>2. Allows only the widget host to update the widgets added to it. It cannot be used to update widgets added to other hosts.|
The following describes the typical use cases of widget updates:
- [Configuring a Widget to Update Periodically](arkts-ui-widget-update-by-time.md)
- [Updating Local and Online Images](arkts-ui-widget-image-update.md)
- [Updating Widget Content by State](arkts-ui-widget-update-by-status.md)
- [Updating Widget Content by Widget Host (for System Applications Only)](arkts-ui-widget-content-update.md)
# Widget Lifecycle Management
When creating an ArkTS widget, you need to implement the [FormExtensionAbility](../reference/apis/js-apis-app-form-formExtensionAbility.md) lifecycle APIs.
1. Import related modules to **EntryFormAbility.ts**.
```ts
import formInfo from '@ohos.app.form.formInfo';
import formBindingData from '@ohos.app.form.formBindingData';
import FormExtensionAbility from '@ohos.app.form.FormExtensionAbility';
import formProvider from '@ohos.app.form.formProvider';
```
2. In **EntryFormAbility.ts**, implement the [FormExtensionAbility](../reference/apis/js-apis-app-form-formExtensionAbility.md) lifecycle APIs, including **onAddForm**, whose **want** parameter can be used to obtain the widget information through [FormParam](../reference/apis/js-apis-app-form-formInfo.md#formparam).
```typescript
import formInfo from '@ohos.app.form.formInfo';
import formBindingData from '@ohos.app.form.formBindingData';
import FormExtensionAbility from '@ohos.app.form.FormExtensionAbility';
import formProvider from '@ohos.app.form.formProvider';
export default class EntryFormAbility extends FormExtensionAbility {
onAddForm(want) {
console.info('[EntryFormAbility] onAddForm');
// Obtain the unique widget ID formId from the want parameter.
let formId: string = want.parameters[formInfo.FormParam.IDENTITY_KEY];
// Called when the widget is created. The widget provider should return the widget data binding class.
let obj = {
'title': 'titleOnAddForm',
'detail': 'detailOnAddForm'
};
let formData = formBindingData.createFormBindingData(obj);
return formData;
}
onCastToNormalForm(formId) {
// Called when the form provider is notified that a temporary form is successfully
// converted to a normal form.
// Called when the widget host converts the temporary widget into a normal one. The widget provider should do something to respond to the conversion.
console.info(`[EntryFormAbility] onCastToNormalForm, formId: ${formId}`);
}
onUpdateForm(formId) {
// Override this method to support scheduled updates, periodic updates, or updates requested by the widget host.
console.info('[EntryFormAbility] onUpdateForm');
let obj = {
'title': 'titleOnUpdateForm',
'detail': 'detailOnUpdateForm'
};
let formData = formBindingData.createFormBindingData(obj);
formProvider.updateForm(formId, formData).catch((err) => {
if (err) {
// Print errors.
console.error(`[EntryFormAbility] Failed to updateForm. Code: ${err.code}, message: ${err.message}`);
return;
}
});
}
onChangeFormVisibility(newStatus) {
// Called when the form provider receives form events from the system.
// The callback is performed only when formVisibleNotify is set to true and the application is a system application.
console.info('[EntryFormAbility] onChangeFormVisibility');
}
onFormEvent(formId, message) {
// Called when a specified message event defined by the form provider is triggered.
// If the widget supports event triggering, override this method and implement the trigger.
console.info('[EntryFormAbility] onFormEvent');
}
onRemoveForm(formId) {
// Called to notify the form provider that a specified form has been destroyed.
// Called when the corresponding widget is deleted. The input parameter is the ID of the deleted card.
console.info('[EntryFormAbility] onRemoveForm');
}
onConfigurationUpdate(config) {
// Called when the system configuration is updated.
console.info('[EntryFormAbility] configurationUpdate:' + JSON.stringify(config));
}
onAcquireFormState(want) {
// Called to return a {@link FormState} object.
// Called when the widget provider receives the status query result of a widget. By default, the initial state of the widget is returned.
return formInfo.FormState.READY;
}
}
```
> **NOTE**
> The FormExtensionAbility cannot reside in the background. Therefore, continuous tasks cannot be processed in the widget lifecycle callbacks. The FormExtensionAbility persists for 5 seconds after the lifecycle callback is completed and will exit if no new lifecycle callback is invoked during this time frame. For the service logic that may take more than 5 seconds to complete, it is recommended that you [start the application](arkts-ui-widget-event-uiability.md). After the processing is complete, use the [updateForm](../reference/apis/js-apis-app-form-formProvider.md#updateform) to notify the widget of the update.
# ArkTS Widget Related Modules
**Figure 1** ArkTS widget related modules
![WidgetModules](figures/WidgetModules.png)
- [FormExtensionAbility](../reference/apis/js-apis-app-form-formExtensionAbility.md): provides lifecycle callbacks invoked when a widget is created, destroyed, or updated.
- [FormExtensionContext](../reference/apis/js-apis-inner-application-formExtensionContext.md): provides context for FormExtensionAbilities. You can use the APIs of this module to start FormExtensionAbilities.
- [formProvider](../reference/apis/js-apis-app-form-formProvider.md): provides APIs related to the widget provider. You can use the APIs to update a widget, set the next update time for a widget, obtain widget information, and request a widget release.
- [formInfo](../reference/apis/js-apis-app-form-formInfo.md): provides types and enums related to the widget information and state.
- [formBindingData](../reference/apis/js-apis-app-form-formBindingData.md): provides APIs for widget data binding. You can use the APIs to create a **FormBindingData** object and obtain related information.
- [Page Layout (Card.ets)](arkts-ui-widget-page-overview.md): provides APIs for a declarative paradigm UI.
- [ArkTS widget capabilities](arkts-ui-widget-event-overview.md): include the **postCardAction** API used for interaction between the widget internal and the provider application and can be called only in the widget.
- [ArkTS widget capability list](arkts-ui-widget-page-overview.md#page-capabilities-supported-by-arkts-widgets): lists the APIs, components, events, attributes, and lifecycle callbacks that can be used in ArkTS widgets.
- [Widget configuration](arkts-ui-widget-configuration.md): includes FormExtensionAbility configuration and widget configuration.
- Configure FormExtensionAbility information under **extensionAbilities** in the [module.json5 file](../quick-start/module-configuration-file.md).
- Configure the widget configuration information (**WidgetCard.ets**) in the [form_config.json](arkts-ui-widget-configuration.md) file in **resources/base/profile**.
# Using Animations in the Widget
To make your ArkTS widget more engaging, you can apply animations to it, including [explicit animation](../reference/arkui-ts/ts-explicit-animation.md), [attribute animation](../reference/arkui-ts/ts-animatorproperty.md), and [component transition](../reference/arkui-ts/ts-transition-animation-component.md). Note the following restrictions when using the animations in ArkTS widgets.
**Table 1** Restrictions on animation parameters
| Name| Description| Description|
| -------- | -------- | -------- |
| duration | Animation playback duration| The maximum value is 1 second. If a larger value is set, the animation is still played for 1 second.|
| tempo | Animation playback speed.| Do not set this parameter in the widget. Use the default value 1.|
| delay | Animation delay duration.| Do not set this parameter in the widget. Use the default value 0.|
| iterations | Number of times that the animation is played.| Do not set this parameter in the widget. Use the default value 1.|
The following sample code implements the animation effect of button rotation:
![WidgetAnimation](figures/WidgetAnimation.gif)
```ts
@Entry
@Component
struct AttrAnimationExample {
@State rotateAngle: number = 0;
build() {
Column() {
Button('change rotate angle')
.onClick(() => {
this.rotateAngle = 90;
})
.margin(50)
.rotate({ angle: this.rotateAngle })
.animation({
curve: Curve.EaseOut,
playMode: PlayMode.AlternateReverse
})
}.width('100%').margin({ top: 20 })
}
}
```
# Applying Custom Drawing in the Widget
You can apply custom drawing in your ArkTS widget to create a more vibrant experience. Use the [Canvas](../reference/arkui-ts/ts-components-canvas-canvas.md) component to create a canvas on the widget, and then use the [CanvasRenderingContext2D](../reference/arkui-ts/ts-canvasrenderingcontext2d.md) object to draw custom graphics on the canvas. The following code shows how to draw a smiling face in the center of the canvas.
```typescript
@Entry
@Component
struct Card {
private canvasWidth: number = 0;
private canvasHeight: number = 0;
// Initialize CanvasRenderingContext2D and RenderingContextSettings.
private settings: RenderingContextSettings = new RenderingContextSettings(true);
private context: CanvasRenderingContext2D = new CanvasRenderingContext2D(this.settings);
build() {
Column() {
Row() {
Canvas(this.context)
.margin('5%')
.width('90%')
.height('90%')
.onReady(() => {
console.info('[ArkTSCard] onReady for canvas draw content');
// Obtain the actual width and height of the canvas in the onReady callback.
this.canvasWidth = this.context.width;
this.canvasHeight = this.context.height;
// Draw the background of the canvas.
this.context.fillStyle = 'rgba(203, 154, 126, 1.00)';
this.context.fillRect(0, 0, this.canvasWidth, this.canvasHeight);
// Draw a red circle in the center of the canvas.
this.context.beginPath();
let radius = this.context.width / 3
let circleX = this.context.width / 2
let circleY = this.context.height / 2
this.context.moveTo(circleX - radius, circleY);
this.context.arc(circleX, circleY, radius, 2 * Math.PI, 0, true);
this.context.closePath();
this.context.fillStyle = 'red';
this.context.fill();
// Draw the left eye of the smiling face.
let leftR = radius / 4
let leftX = circleX - (radius / 2)
let leftY = circleY - (radius / 3.5)
this.context.beginPath();
this.context.arc(leftX, leftY, leftR, 0, Math.PI, true);
this.context.strokeStyle = '#ffff00'
this.context.lineWidth = 10
this.context.stroke()
// Draw the right eye of the smiling face.
let rightR = radius / 4
let rightX = circleX + (radius / 2)
let rightY = circleY - (radius / 3.5)
this.context.beginPath();
this.context.arc(rightX, rightY, rightR, 0, Math.PI, true);
this.context.strokeStyle = '#ffff00'
this.context.lineWidth = 10
this.context.stroke()
// Draw the mouth of the smiling face.
let mouthR = radius / 2.5
let mouthX = circleX
let mouthY = circleY + (radius / 3)
this.context.beginPath();
this.context.arc(mouthX, mouthY, mouthR, Math.PI, 0, true);
this.context.strokeStyle = '#ffff00'
this.context.lineWidth = 10
this.context.stroke()
})
}
}.height('100%').width('100%')
}
}
```
The figure below shows the effect.
![WidgetCanvasDemo](figures/WidgetCanvasDemo.jpeg)
# Widget Page Capability Overview
You can leverage the ArkUI declarative paradigm to develop ArkTS widget pages. The following widget pages are automatically generated by a DevEco Studio template. You can adjust the pages based on the real-world service scenarios.
![WidgetPreviewPage](figures/WidgetPreviewPage.png)
ArkTS widgets have full capabilities of JS widgets, with added animation and custom drawing capabilities plus partial support for components, events, animations, data management, and state management capabilities of the [declarative paradigm](../reference/arkui-ts/ts-components-summary.md). For details, see [Page Capabilities Supported by ArkTS Widgets](#page-capabilities-supported-by-arkts-widgets).
## Page Capabilities Supported by ArkTS Widgets
For details about the page capabilities supported by ArkTS widgets, see [Learning ArkTS](../quick-start/arkts-create-custom-components.md) and [ArkTS-based Declarative Development Paradigm](../reference/arkui-ts/ts-components-summary.md).
Only the APIs marked with "supported in ArkTS widgets" can be used for ArkTS widgets. Pay special attention to the capability differences with applications.
For example, the following description indicates that the @Component decorator can be used in ArkTS widgets.
![WidgetSupportApi](figures/WidgetSupportApi.png)
# Updating Widget Content by State
Multiple widgets of the same application can be configured to implement different features. For example, two weather widgets can be added to the home screen: one for displaying the weather of London, and the other Beijing. The widget is set to be updated at 07:00 every morning. It needs to detect the configured city, and then updates the city-specific weather information. The following example describes how to dynamically update the widget content based on the state.
- Widget configuration file: Configure the widget to be updated at 07:00 every morning.
```json
{
"forms": [
{
"name": "widget",
"description": "This is a service widget.",
"src": "./ets/widget/pages/WidgetCard.ets",
"uiSyntax": "arkts",
"window": {
"designWidth": 720,
"autoDesignWidth": true
},
"colorMode": "auto",
"isDefault": true,
"updateEnabled": true,"scheduledUpdateTime": "07:00",
"updateDuration": 0,
"defaultDimension": "2*2",
"supportDimensions": ["2*2"]
}
]
}
```
- Widget page: A widget has different states and needs to be updated by state. When the state changes, **postCardAction** is called to notify the EntryFormAbility.
```ts
let storage = new LocalStorage();
@Entry(storage)
@Component
struct WidgetCard {
@LocalStorageProp('textA') textA: string = 'To be updated...';
@LocalStorageProp('textB') textB: string ='To be updated...';
@State selectA: boolean = false;
@State selectB: boolean = false;
build() {
Column() {
Row() {
Checkbox({ name: 'checkbox1', group: 'checkboxGroup' })
.select(false)
.onChange((value: boolean) => {
this.selectA = value;
postCardAction(this, {
'action': 'message',
'params': {
'selectA': JSON.stringify(value)
}
});
})
Text ('State A')
}
Row() {
Checkbox({ name: 'checkbox2', group: 'checkboxGroup' })
.select(false)
.onChange((value: boolean) => {
this.selectB = value;
postCardAction(this, {
'action': 'message',
'params': {
'selectB': JSON.stringify(value)
}
});
})
Text ('State B')
}
Row() {// Content that is updated only in state A
Text('State A: ')
Text(this.textA)
}
Row() { // Content that is updated only in state B
Text ('State B:')
Text(this.textB)
}
}.padding('10%')
}
}
```
- EntryFormAbility: The widget state data is stored in the local database. When the update event callback is triggered, the current widget state is obtained through **formId**, and then content is updated based on the state obtained.
```ts
import formInfo from '@ohos.app.form.formInfo'
import formProvider from '@ohos.app.form.formProvider';
import formBindingData from '@ohos.app.form.formBindingData';
import FormExtensionAbility from '@ohos.app.form.FormExtensionAbility';
import dataStorage from '@ohos.data.storage'
export default class EntryFormAbility extends FormExtensionAbility {
onAddForm(want) {
let formId = want.parameters[formInfo.FormParam.IDENTITY_KEY];
let isTempCard: boolean = want.parameters[formInfo.FormParam.TEMPORARY_KEY];
if (isTempCard === false) {// If the widget is a normal one, the widget information is persisted.
console.info('Not temp card, init db for:' + formId);
let storeDB = dataStorage.getStorageSync(this.context.filesDir + 'myStore')
storeDB.putSync('A' + formId, 'false');
storeDB.putSync('B' + formId, 'false');
storeDB.flushSync();
}
let formData = {};
return formBindingData.createFormBindingData(formData);
}
onRemoveForm(formId) {
console.info('onRemoveForm, formId:' + formId);
let storeDB = dataStorage.getStorageSync(this.context.filesDir + 'myStore')
storeDB.deleteSync('A' + formId);
storeDB.deleteSync('B' + formId);
}
// If the widget is a temporary one, it is recommended that the widget information be persisted when the widget is converted to a normal one.
onCastToNormalForm(formId) {
console.info('onCastToNormalForm, formId:' + formId);
let storeDB = dataStorage.getStorageSync(this.context.filesDir + 'myStore')
storeDB.putSync('A' + formId, 'false');
storeDB.putSync('B' + formId, 'false');
storeDB.flushSync();
}
onUpdateForm(formId) {
let storeDB = dataStorage.getStorageSync(this.context.filesDir + 'myStore')
let stateA = storeDB.getSync('A' + formId, 'false').toString()
let stateB = storeDB.getSync('B' + formId, 'false').toString()
// Update textA in state A.
if (stateA === 'true') {
let formInfo = formBindingData.createFormBindingData({
'textA': 'AAA'
})
formProvider.updateForm(formId, formInfo)
}
// Update textB in state B.
if (stateB === 'true') {
let formInfo = formBindingData.createFormBindingData({
'textB': 'BBB'
})
formProvider.updateForm(formId, formInfo)
}
}
onFormEvent(formId, message) {
// Store the widget state.
console.info('onFormEvent formId:' + formId + 'msg:' + message);
let storeDB = dataStorage.getStorageSync(this.context.filesDir + 'myStore')
let msg = JSON.parse(message)
if (msg.selectA != undefined) {
console.info('onFormEvent selectA info:' + msg.selectA);
storeDB.putSync('A' + formId, msg.selectA);
}
if (msg.selectB != undefined) {
console.info('onFormEvent selectB info:' + msg.selectB);
storeDB.putSync('B' + formId, msg.selectB);
}
storeDB.flushSync();
}
};
```
> **NOTE**
> When the local database is used for widget information persistence, it is recommended that [TEMPORARY_KEY](../reference/apis/js-apis-app-form-formInfo.md#formparam) be used to determine whether the currently added widget is a normal one in the [onAddForm](../reference/apis/js-apis-app-form-formExtensionAbility.md#onaddform) lifecycle callback. If the widget is a normal one, the widget information is directly persisted. If the widget is a temporary one, the widget information is persisted when the widget is converted to a normal one ([onCastToNormalForm](../reference/apis/js-apis-app-form-formExtensionAbility.md#oncasttonormalform)). In addition, the persistent widget information needs to be deleted when the widget is destroyed ([onRemoveForm](../reference/apis/js-apis-app-form-formExtensionAbility.md#onremoveform)), preventing the database size from continuously increasing due to repeated widget addition and deletion.
# Configuring a Widget to Update Periodically
Before configuring a widget to update periodically, enable the periodic update feature by setting the **updateEnabled** field to **true** in the **form_config.json** file.
The widget framework provides the following modes of updating widgets periodically:
- Set the update interval: The widget will be updated at the specified interval. You can specify the interval by setting the [updateDuration](arkts-ui-widget-configuration.md) field in the **form_config.json** file. For example, you can configure the widget to update once an hour.
> **NOTE**
>
> **updateDuration** takes precedence over **scheduledUpdateTime**. If both are specified, the value specified by **updateDuration** is used.
```json
{
"forms": [
{
"name": "widget",
"description": "This is a service widget.",
"src": "./ets/widget/pages/WidgetCard.ets",
"uiSyntax": "arkts",
"window": {
"designWidth": 720,
"autoDesignWidth": true
},
"colorMode": "auto",
"isDefault": true,
"updateEnabled": true, // Enable the periodic update feature.
"scheduledUpdateTime": "10:30",
"updateDuration": 2, // Set the interval to update the widget. The value is a natural number, in the unit of 30 minutes.
"defaultDimension": "2*2",
"supportDimensions": ["2*2"]
}
]
}
```
- Set the scheduled update time: The widget will be updated at the scheduled time every day. You can specify the time by setting the [scheduledUpdateTime](arkts-ui-widget-configuration.md) field in the **form_config.json** file. For example, you can configure the widget to update at 10:30 a.m. every day.
> **NOTE**
>
> **updateDuration** takes precedence over **scheduledUpdateTime**. For the **scheduledUpdateTime** settings to take effect, set **updateDuration** to **0**.
```json
{
"forms": [
{
"name": "widget",
"description": "This is a service widget.",
"src": "./ets/widget/pages/WidgetCard.ets",
"uiSyntax": "arkts",
"window": {
"designWidth": 720,
"autoDesignWidth": true
},
"colorMode": "auto",
"isDefault": true,
"updateEnabled": true, // Enable the periodic update feature.
"scheduledUpdateTime": "10:30", // Set the scheduled time to update the widget.
"updateDuration": 0,
"defaultDimension": "2*2",
"supportDimensions": ["2*2"]
}
]
}
```
- Set the next update time: The widget will be updated next time at the specified time. You can specify the time by calling the [setFormNextRefreshTime()](../reference/apis/js-apis-app-form-formProvider.md#setformnextrefreshtime) API. The minimum update interval is 5 minutes. For example, you can configure the widget to update within 5 minutes after the API is called.
```ts
import formProvider from '@ohos.app.form.formProvider';
let formId = '123456789'; // Use the actual widget ID in real-world scenarios.
try {
// Configure the widget to update in 5 minutes.
formProvider.setFormNextRefreshTime(formId, 5, (err, data) => {
if (err) {
console.error(`Failed to setFormNextRefreshTime. Code: ${err.code}, message: ${err.message}`);
return;
} else {
console.info('Succeeded in setFormNextRefreshTimeing.');
}
});
} catch (err) {
console.error(`Failed to setFormNextRefreshTime. Code: ${err.code}, message: ${err.message}`);
}
```
When periodic update is triggered, the system calls the [onUpdateForm()](../reference/apis/js-apis-app-form-formExtensionAbility.md#onupdateform) lifecycle callback of the FormExtensionAbility. In the callback, [updateForm()](../reference/apis/js-apis-app-form-formProvider.md#updateform) can be used to update the widget by the provider. For details about how to use **onUpdateForm()**, see [Updating Widget Content Through FormExtensionAbility](arkts-ui-widget-event-formextensionability.md).
> **NOTE**
> 1. Each widget can be updated at the specified interval for a maximum of 50 times every day, including updates triggered by setting [updateDuration](arkts-ui-widget-configuration.md) or calling [setFormNextRefreshTime()](../reference/apis/js-apis-app-form-formProvider.md#setformnextrefreshtime). When the limit is reached, the widget cannot be updated in this mode again. The number of update times is reset at 00:00 every day.
>
> 2. The same timer is used for timing updates at the specified interval. Therefore, the first scheduled update of widgets may have a maximum deviation of 30 minutes. For example, the first widget A (updated every half an hour) is added at 03:20. The timer starts and triggers an update every half an hour. The second widget B (updated every half an hour) is added at 03:40. When the timer event is triggered at 03:50, widget A is updated, and widget B will be updated at 04:20 next time.
>
> 3. Updates at the specified interval and updates at the scheduled time are triggered only when the screen is on. When the screen is off, the update action is merely recorded. When the screen is on, the update action is performed.
# ArkTS Widget Working Principles
## Implementation Principles
**Figure 1** ArkTS widget implementation principles
![WidgetPrinciple](figures/WidgetPrinciple.png)
- Widget host: an application that displays the widget content and controls the widget location. Only the system application can function as a widget host.
- Widget provider: an application that provides the widget content to display and controls how widget components are laid out and how they interact with users.
- Widget Manager: a resident agent that manages widgets in the system. It provides the [formProvider](../reference/apis/js-apis-app-form-formProvider.md) and [formHost](../reference/apis/js-apis-app-form-formHost.md) APIs as well as widget management, usage, and periodic updates.
- Widget rendering service: a service that manages widget rendering instances. Widget rendering instances are bound to the [widget components](../reference/arkui-ts/ts-basic-components-formcomponent.md) on the widget host on a one-to-one basis. The widget rendering service runs the widget page code **widgets.abc** for rendering, and sends the rendered data to the corresponding widget component on the widget host.
**Figure 2** Working principles of the ArkTS widget rendering service
![WidgetRender](figures/WidgetRender.png)
Unlike JS widgets, ArkTS widgets support logic code running. To avoid potential ArkTS widget issues from affecting the use of applications, the widget page code **widgets.abc** is executed by the widget rendering service, which is managed by the Widget Manager. Each widget component of a widget host corresponds to a rendering instance in the widget rendering service. Rendering instances of an application provider run in the same virtual machine operating environment, and rendering instances of different application providers run in different virtual machine operating environments. In this way, the resources and state data are isolated between widgets of different application providers. During development, pay attention to the use of the [globalThis](uiability-data-sync-with-ui.md#using-globalthis-between-uiability-and-page) object. Use one **globalThis** object for widgets by the same application provider, and different **globalThis** objects for widgets by different application providers.
## Advantages of ArkTS Widgets
As a quick entry to applications, ArkTS widgets have the following advantages over JS widgets:
- Improved development experience and efficiency, thanks to the unified development paradigm
ArkTS widgets share the same declarative UI development framework as application pages. This means that the page layouts can be directly reused in widgets, improving development experience and efficiency.
**Figure 3** Comparison of widget project structures
![WidgetProject](figures/WidgetProject.png)
- More widget features
- Animation: The ArkTS widget supports the [attribute animation](../reference/arkui-ts/ts-animatorproperty.md) and [explicit animation](../reference/arkui-ts/ts-explicit-animation.md) capabilities, which can be leveraged to deliver a more engaging experience.
- Custom drawing: The ArkTS widget allows you to draw graphics with the [Canvas](../reference/arkui-ts/ts-components-canvas-canvas.md) component to present information more vividly.
- Logic code execution: The capability to run logic code in widgets means that service logic can be self-closed in widgets, expanding the service application scenarios of widgets.
## Constraints on ArkTS Widgets
Compared with JS widgets, ArkTS widgets provide more capabilities, but they are also more prone to malicious behavior. The ArkTS widget is displayed in the widget host, which is usually the home screen. To ensure user experience and power consumption, the ArkTS widget capability is restricted as follows:
- The .so file cannot be loaded.
- The native programming language cannot be used for development.
- Only [partial](arkts-ui-widget-page-overview.md) components, events, animations, data management, state management, and API capabilities of the declarative paradigm are supported.
- The event processing of the widget is independent of that of the widget host. It is recommended that you do not use the left and right sliding components when the widget host supports left and right swipes to prevent gesture conflicts.
The following features are coming to ArkTS widgets in later versions:
- Breakpoint debugging
- import statements
- Instant preview
# Removing Sticky Common Events
## When to Use
Subscribers can receive sticky common events that have been sent. If the events are no longer forwarded, the event publisher needs to remove them. OpenHarmony provides an API for removing sticky common events.
## Available APIs
For details, see [Common Event](../reference/apis/js-apis-commonEventManager.md)
| Name| Description|
| -------- | -------- |
| removeStickyCommonEvent(event: string, callback: AsyncCallback\<void>): void | Removes a sticky common event.|
## How to Develop
1. Import the module.
```ts
import commonEventManager from '@ohos.commonEventManager';
```
2. The sticky common event to be removed must have been released by the application. For details about how to release sticky common events, see [Publishing Common Events](common-event-publish.md).
```ts
CommonEventManager.removeStickyCommonEvent("sticky_event", (err) => { // sticky_event indicates the name of the sticky common event to remove.
if (err) {
console.info(`Remove sticky event AsyncCallback failed, errCode: ${err.code}, errMes: ${err.message}`);
return;
}
console.info(`Remove sticky event AsyncCallback success`);
}
});
```
...@@ -22,8 +22,6 @@ A static subscriber is started once it receives a target event published by the ...@@ -22,8 +22,6 @@ A static subscriber is started once it receives a target event published by the
You can implement service logic in the **onReceiveEvent** callback. You can implement service logic in the **onReceiveEvent** callback.
2. Project Configuration for a Static Subscriber 2. Project Configuration for a Static Subscriber
After writing the static subscriber code, configure the subscriber in the **module.json5** file. The configuration format is as follows: After writing the static subscriber code, configure the subscriber in the **module.json5** file. The configuration format is as follows:
...@@ -35,12 +33,12 @@ A static subscriber is started once it receives a target event published by the ...@@ -35,12 +33,12 @@ A static subscriber is started once it receives a target event published by the
"extensionAbilities": [ "extensionAbilities": [
{ {
"name": "StaticSubscriber", "name": "StaticSubscriber",
"srcEntrance": "./ets/StaticSubscriber/StaticSubscriber.ts", "srcEntry": "./ets/StaticSubscriber/StaticSubscriber.ts",
"description": "$string:StaticSubscriber_desc", "description": "$string:StaticSubscriber_desc",
"icon": "$media:icon", "icon": "$media:icon",
"label": "$string:StaticSubscriber_label", "label": "$string:StaticSubscriber_label",
"type": "staticSubscriber", "type": "staticSubscriber",
"visible": true, "exported": true,
"metadata": [ "metadata": [
{ {
"name": "ohos.extension.staticSubscriber", "name": "ohos.extension.staticSubscriber",
...@@ -56,7 +54,7 @@ A static subscriber is started once it receives a target event published by the ...@@ -56,7 +54,7 @@ A static subscriber is started once it receives a target event published by the
Pay attention to the following fields in the JSON file: Pay attention to the following fields in the JSON file:
- **srcEntrance**: entry file path of the ExtensionAbility, that is, the file path of the static subscriber declared in Step 2. - **srcEntry**: entry file path of the ExtensionAbility, that is, the file path of the static subscriber declared in Step 2.
- **type**: ExtensionAbility type. For a static subscriber, set this field to **staticSubscriber**. - **type**: ExtensionAbility type. For a static subscriber, set this field to **staticSubscriber**.
......
...@@ -60,15 +60,15 @@ To implement EnterpriseAdminExtensionAbility, you need to activate the device ad ...@@ -60,15 +60,15 @@ To implement EnterpriseAdminExtensionAbility, you need to activate the device ad
}; };
``` ```
4. Register **ServiceExtensionAbility** in the [**module.json5**](../quick-start/module-configuration-file.md) file corresponding to the project module. Set **type** to **enterpriseAdmin** and **srcEntrance** to the path of the ExtensionAbility code. 4. Register **ServiceExtensionAbility** in the [**module.json5**](../quick-start/module-configuration-file.md) file corresponding to the project module. Set **type** to **enterpriseAdmin** and **srcEntry** to the path of the ExtensionAbility code.
```ts ```ts
"extensionAbilities": [ "extensionAbilities": [
{ {
"name": "ohos.samples.enterprise_admin_ext_ability", "name": "ohos.samples.enterprise_admin_ext_ability",
"type": "enterpriseAdmin", "type": "enterpriseAdmin",
"visible": true, "exported": true,
"srcEntrance": "./ets/enterpriseextability/EnterpriseAdminAbility.ts" "srcEntry": "./ets/enterpriseextability/EnterpriseAdminAbility.ts"
} }
] ]
``` ```
......
...@@ -54,7 +54,7 @@ The minimum template contains four files: **KeyboardController.ts**, **InputMeth ...@@ -54,7 +54,7 @@ The minimum template contains four files: **KeyboardController.ts**, **InputMeth
1. **InputMethodService.ts** file: 1. **InputMethodService.ts** file:
In this file, add the dependency package for importing InputMethodExtensionAbility. Customize a class that inherits from InputMethodExtensionAbility and add the required lifecycle callbacks. In the **InputMethodService.ts** file, add the dependency package for importing InputMethodExtensionAbility. Customize a class that inherits from InputMethodExtensionAbility and add the required lifecycle callbacks.
```ts ```ts
import InputMethodExtensionAbility from '@ohos.InputMethodExtensionAbility'; import InputMethodExtensionAbility from '@ohos.InputMethodExtensionAbility';
...@@ -233,7 +233,7 @@ The minimum template contains four files: **KeyboardController.ts**, **InputMeth ...@@ -233,7 +233,7 @@ The minimum template contains four files: **KeyboardController.ts**, **InputMeth
Add the path to this file to the **src** field in the **resources/base/profile/main_pages.json** file. Add the path to this file to the **src** field in the **resources/base/profile/main_pages.json** file.
```ets ```ts
import { numberSourceListData, sourceListType } from './keyboardKeyData' import { numberSourceListData, sourceListType } from './keyboardKeyData'
@Component @Component
...@@ -342,7 +342,7 @@ The minimum template contains four files: **KeyboardController.ts**, **InputMeth ...@@ -342,7 +342,7 @@ The minimum template contains four files: **KeyboardController.ts**, **InputMeth
} }
``` ```
Register the InputMethodExtensionAbility in the [module.json5 file](../quick-start/module-configuration-file.md) corresponding to the target module. Set **type** to **"inputMethod"** and **srcEntrance** to the code path of the InputMethodExtensionAbility component. Register the InputMethodExtensionAbility in the [module.json5 file](../quick-start/module-configuration-file.md) corresponding to the target module. Set **type** to **"inputMethod"** and **srcEntry** to the code path of the InputMethodExtensionAbility component.
```ts ```ts
{ {
...@@ -353,9 +353,9 @@ The minimum template contains four files: **KeyboardController.ts**, **InputMeth ...@@ -353,9 +353,9 @@ The minimum template contains four files: **KeyboardController.ts**, **InputMeth
"description": "inputMethod", "description": "inputMethod",
"icon": "$media:icon", "icon": "$media:icon",
"name": "InputMethodExtAbility", "name": "InputMethodExtAbility",
"srcEntrance": "./ets/inputmethodextability/InputMethodService.ts", "srcEntry": "./ets/inputmethodextability/InputMethodService.ts",
"type": "inputMethod", "type": "inputMethod",
"visible": true, "exported": true,
} }
] ]
} }
......
# Service Widget Overview
A service widget (also called widget) is a set of UI components that display important information or operations specific to an application. It provides users with direct access to a desired application service, without the need to open the application first. A widget usually appears as a part of the UI of another application (which currently can only be a system application, such as the home screen) and provides basic interactive features such as opening a UI page or sending a message.
## Service Widget Architecture
**Figure 1** Service widget architecture
![WidgetArchitecture](figures/WidgetArchitecture.png)
Before you get started, it would be helpful if you have a basic understanding of the following concepts:
- Widget host: an application that displays the widget content and controls the widget location. An example is the home screen in the preceding figure.
- Application icon: an application entry icon, clicking which starts the application process. The icon content does not support interactions.
- Widget: an interactive UI in various sizes. It may provide buttons to implement different functions, such as the button to [update the widget content](arkts-ui-widget-event-formextensionability.md) or [switch to an application](arkts-ui-widget-event-router.md).
- Card provider: an application that provides service widget content to be displayed. It controls the display content, display logic, and component click events triggered on a service widget.
- FormExtensionAbility: widget service logic module, which provides lifecycle callbacks invoked when a widget is created, destroyed, or updated.
- Widget page: widget UI module, which contains display and interaction information such as components, layouts, and events.
Below is the typical procedure of using the widget:
**Figure 2** Typical procedure of using the widget
![WidgetUse](figures/WidgetUse.png)
1. Touch and hold an application icon on the home screen to display the shortcut menu.
2. Touch **Service widget** to access the preview screen.
3. Touch the **Add to home** button. The widget is then added to the home screen.
## Widget UI Development Mode
In the stage model, the UI of a widget can be developed in [ArkTS](arkts-ui-widget-working-principles.md) or [JS](js-ui-widget-development.md).
- A widget developed in the ArkTS-based declarative development paradigm is called ArkTS widget.
- A widget developed in the JS-compatible web-like development paradigm is called JS widget.
ArkTS widgets and JS widgets have different implementation principles and features. The following table lists the differences in capabilities.
| Category| JS widget| ArkTS widget|
| -------- | -------- | -------- |
| Development paradigm| Web-like paradigm| Declarative paradigm|
| Component capability| Supported| Supported|
| Layout capability| Supported| Supported|
| Event capability| Supported| Supported|
| Custom animation| Not supported| Supported|
| Custom drawing| Not supported| Supported|
| Logic code execution (excluding the import capability)| Not supported| Supported|
As can be seen above, ArkTS widgets have more capabilities and use cases than JS widgets. Therefore, ArkTS widgets are always recommended, except for the case where the widget consists of only static pages.
...@@ -158,5 +158,4 @@ httpRequest.request2( ...@@ -158,5 +158,4 @@ httpRequest.request2(
httpRequest.destroy(); httpRequest.destroy();
} }
); );
``` ```
\ No newline at end of file
...@@ -81,7 +81,7 @@ For the complete list of APIs and example code, see [Network Connection Manageme ...@@ -81,7 +81,7 @@ For the complete list of APIs and example code, see [Network Connection Manageme
6. Call **conn.unregister()** to unsubscribe from the network status changes if required. 6. Call **conn.unregister()** to unsubscribe from the network status changes if required.
```js ```js
// Import the connection namespace. // Import the connection namespace.
import connection from '@ohos.net.connection' import connection from '@ohos.net.connection'
let netCap = { let netCap = {
...@@ -128,7 +128,7 @@ conn.unregister((err, data) => { ...@@ -128,7 +128,7 @@ conn.unregister((err, data) => {
2. Call **getAllNets** to obtain the list of all connected networks. 2. Call **getAllNets** to obtain the list of all connected networks.
```js ```js
// Import the connection namespace. // Import the connection namespace.
import connection from '@ohos.net.connection' import connection from '@ohos.net.connection'
// Obtain the list of all connected networks. // Obtain the list of all connected networks.
...@@ -154,7 +154,7 @@ connection.getAllNets((err, data) => { ...@@ -154,7 +154,7 @@ connection.getAllNets((err, data) => {
4. Call **getConnectionProperties** to obtain the connection information of the data network specified by **NetHandle**. 4. Call **getConnectionProperties** to obtain the connection information of the data network specified by **NetHandle**.
```js ```js
// Import the connection namespace. // Import the connection namespace.
import connection from '@ohos.net.connection' import connection from '@ohos.net.connection'
// Call getDefaultNet to obtain the default data network specified by **NetHandle**. // Call getDefaultNet to obtain the default data network specified by **NetHandle**.
......
...@@ -44,7 +44,7 @@ For the complete list of APIs and example code, see [Ethernet Connection](../ref ...@@ -44,7 +44,7 @@ For the complete list of APIs and example code, see [Ethernet Connection](../ref
5. Call **getIfaceConfig** in user mode to obtain the static network attributes of the **eth0** port. By default, an unconfigured Ethernet network uses the DHCP mode, in which the Ethernet network obtains the automatically assigned network attributes. 5. Call **getIfaceConfig** in user mode to obtain the static network attributes of the **eth0** port. By default, an unconfigured Ethernet network uses the DHCP mode, in which the Ethernet network obtains the automatically assigned network attributes.
```js ```js
// Import the ethernet namespace from @ohos.net.ethernet. // Import the ethernet namespace from @ohos.net.ethernet.
import ethernet from '@ohos.net.ethernet' import ethernet from '@ohos.net.ethernet'
// Call getAllActiveIfaces to obtain the list of all active network ports. // Call getAllActiveIfaces to obtain the list of all active network ports.
...@@ -96,7 +96,7 @@ ethernet.getIfaceConfig("eth0", (error, data) => { ...@@ -96,7 +96,7 @@ ethernet.getIfaceConfig("eth0", (error, data) => {
6. Call **getIfaceConfig** in user mode to obtain the static network attributes of the **eth0** port. 6. Call **getIfaceConfig** in user mode to obtain the static network attributes of the **eth0** port.
```js ```js
// Import the ethernet namespace from @ohos.net.ethernet. // Import the ethernet namespace from @ohos.net.ethernet.
import ethernet from '@ohos.net.ethernet' import ethernet from '@ohos.net.ethernet'
// Call getAllActiveIfaces to obtain the list of all active network ports. // Call getAllActiveIfaces to obtain the list of all active network ports.
...@@ -158,13 +158,13 @@ ethernet.getIfaceConfig("eth0", (error, data) => { ...@@ -158,13 +158,13 @@ ethernet.getIfaceConfig("eth0", (error, data) => {
4. Call the **off()** method to unsubscribe from **interfaceStateChange** events. 4. Call the **off()** method to unsubscribe from **interfaceStateChange** events.
```js ```js
// Import the ethernet namespace from @ohos.net.ethernet. // Import the ethernet namespace from @ohos.net.ethernet.
import ethernet from '@ohos.net.ethernet' import ethernet from '@ohos.net.ethernet'
// Subscribe to interfaceStateChange events. // Subscribe to interfaceStateChange events.
ethernet.on('interfaceStateChange', ((data) => { ethernet.on('interfaceStateChange', (data) => {
console.log(JSON.stringify(data)); console.log(JSON.stringify(data));
})); });
// Unsubscribe from interfaceStateChange events. // Unsubscribe from interfaceStateChange events.
ethernet.off('interfaceStateChange'); ethernet.off('interfaceStateChange');
......
...@@ -60,7 +60,7 @@ For the complete list of APIs and example code, see [Network Sharing](../referen ...@@ -60,7 +60,7 @@ For the complete list of APIs and example code, see [Network Sharing](../referen
4. Return the callback for successfully starting network sharing. 4. Return the callback for successfully starting network sharing.
```js ```js
// Import the sharing namespace from @ohos.net.sharing. // Import the sharing namespace from @ohos.net.sharing.
import sharing from '@ohos.net.sharing' import sharing from '@ohos.net.sharing'
// Subscribe to network sharing state changes. // Subscribe to network sharing state changes.
...@@ -85,7 +85,7 @@ sharing.startSharing(sharing.SharingIfaceType.SHARING_WIFI, (error) => { ...@@ -85,7 +85,7 @@ sharing.startSharing(sharing.SharingIfaceType.SHARING_WIFI, (error) => {
4. Return the callback for successfully stopping network sharing. 4. Return the callback for successfully stopping network sharing.
```js ```js
// Import the sharing namespace from @ohos.net.sharing. // Import the sharing namespace from @ohos.net.sharing.
import sharing from '@ohos.net.sharing' import sharing from '@ohos.net.sharing'
// Subscribe to network sharing state changes. // Subscribe to network sharing state changes.
...@@ -110,7 +110,7 @@ sharing.stopSharing(sharing.SharingIfaceType.SHARING_WIFI, (error) => { ...@@ -110,7 +110,7 @@ sharing.stopSharing(sharing.SharingIfaceType.SHARING_WIFI, (error) => {
4. Call **stopSharing** to stop network sharing of the specified type and clear the data volume of network sharing. 4. Call **stopSharing** to stop network sharing of the specified type and clear the data volume of network sharing.
```js ```js
// Import the sharing namespace from @ohos.net.sharing. // Import the sharing namespace from @ohos.net.sharing.
import sharing from '@ohos.net.sharing' import sharing from '@ohos.net.sharing'
// Call startSharing to start network sharing of the specified type. // Call startSharing to start network sharing of the specified type.
......
...@@ -87,81 +87,81 @@ The implementation is similar for UDP Socket and TCP Socket connections. The fol ...@@ -87,81 +87,81 @@ The implementation is similar for UDP Socket and TCP Socket connections. The fol
7. Enable the TCP Socket connection to be automatically closed after use. 7. Enable the TCP Socket connection to be automatically closed after use.
```js ```js
import socket from '@ohos.net.socket' import socket from '@ohos.net.socket'
// Create a TCPSocket object. // Create a TCPSocket object.
let tcp = socket.constructTCPSocketInstance(); let tcp = socket.constructTCPSocketInstance();
// Subscribe to TCP Socket connection events. // Subscribe to TCP Socket connection events.
tcp.on('message', value => { tcp.on('message', value => {
console.log("on message") console.log("on message")
let buffer = value.message let buffer = value.message
let dataView = new DataView(buffer) let dataView = new DataView(buffer)
let str = "" let str = ""
for (let i = 0;i < dataView.byteLength; ++i) { for (let i = 0; i < dataView.byteLength; ++i) {
str += String.fromCharCode(dataView.getUint8(i)) str += String.fromCharCode(dataView.getUint8(i))
} }
console.log("on connect received:" + str) console.log("on connect received:" + str)
}); });
tcp.on('connect', () => { tcp.on('connect', () => {
console.log("on connect") console.log("on connect")
}); });
tcp.on('close', () => { tcp.on('close', () => {
console.log("on close") console.log("on close")
}); });
// Bind the local IP address and port number. // Bind the local IP address and port number.
let bindAddress = { let bindAddress = {
address: '192.168.xx.xx', address: '192.168.xx.xx',
port: 1234, // Bound port, for example, 1234. port: 1234, // Bound port, for example, 1234.
family: 1 family: 1
}; };
tcp.bind(bindAddress, err => { tcp.bind(bindAddress, err => {
if (err) { if (err) {
console.log('bind fail'); console.log('bind fail');
return; return;
} }
console.log('bind success'); console.log('bind success');
// Set up a connection to the specified IP address and port number. // Set up a connection to the specified IP address and port number.
let connectAddress = { let connectAddress = {
address: '192.168.xx.xx', address: '192.168.xx.xx',
port: 5678, // Connection port, for example, 5678. port: 5678, // Connection port, for example, 5678.
family: 1 family: 1
}; };
tcp.connect({ tcp.connect({
address: connectAddress, timeout: 6000 address: connectAddress, timeout: 6000
}, err => { }, err => {
if (err) { if (err) {
console.log('connect fail'); console.log('connect fail');
return; return;
} }
console.log('connect success'); console.log('connect success');
// Send data. // Send data.
tcp.send({ tcp.send({
data: 'Hello, server!' data: 'Hello, server!'
}, err => { }, err => {
if (err) { if (err) {
console.log('send fail'); console.log('send fail');
return; return;
} }
console.log('send success'); console.log('send success');
}) })
}); });
}); });
// Enable the TCP Socket connection to be automatically closed after use. Then, disable listening for TCP Socket connection events. // Enable the TCP Socket connection to be automatically closed after use. Then, disable listening for TCP Socket connection events.
setTimeout(() => { setTimeout(() => {
tcp.close((err) => { tcp.close((err) => {
console.log('close socket.') console.log('close socket.')
}); });
tcp.off('message'); tcp.off('message');
tcp.off('connect'); tcp.off('connect');
tcp.off('close'); tcp.off('close');
}, 30 * 1000); }, 30 * 1000);
``` ```
## Implementing Encrypted Data Transmission over TLS Socket Connections ## Implementing Encrypted Data Transmission over TLS Socket Connections
...@@ -184,7 +184,7 @@ TLS Socket connection process on the client: ...@@ -184,7 +184,7 @@ TLS Socket connection process on the client:
7. Enable the TLS Socket connection to be automatically closed after use. 7. Enable the TLS Socket connection to be automatically closed after use.
```js ```js
import socket from '@ohos.net.socket' import socket from '@ohos.net.socket'
// Create a TLS Socket connection (for two-way authentication). // Create a TLS Socket connection (for two-way authentication).
let tlsTwoWay = socket.constructTLSSocketInstance(); let tlsTwoWay = socket.constructTLSSocketInstance();
...@@ -208,7 +208,7 @@ tlsTwoWay.on('close', () => { ...@@ -208,7 +208,7 @@ tlsTwoWay.on('close', () => {
}); });
// Bind the local IP address and port number. // Bind the local IP address and port number.
tlsTwoWay.bind({address: '192.168.xxx.xxx', port: xxxx, family: 1}, err => { tlsTwoWay.bind({ address: '192.168.xxx.xxx', port: xxxx, family: 1 }, err => {
if (err) { if (err) {
console.log('bind fail'); console.log('bind fail');
return; return;
...@@ -280,7 +280,7 @@ tlsTwoWay.on('close', () => { ...@@ -280,7 +280,7 @@ tlsTwoWay.on('close', () => {
}); });
// Bind the local IP address and port number. // Bind the local IP address and port number.
tlsOneWay.bind({address: '192.168.xxx.xxx', port: xxxx, family: 1}, err => { tlsOneWay.bind({ address: '192.168.xxx.xxx', port: xxxx, family: 1 }, err => {
if (err) { if (err) {
console.log('bind fail'); console.log('bind fail');
return; return;
...@@ -318,4 +318,12 @@ tlsTwoWay.close((err) => { ...@@ -318,4 +318,12 @@ tlsTwoWay.close((err) => {
tlsTwoWay.off('connect'); tlsTwoWay.off('connect');
tlsTwoWay.off('close'); tlsTwoWay.off('close');
}); });
``` ```
\ No newline at end of file
## Samples
The following samples are provided to help you better understand how to develop Socket connection features:
- [`Socket`: Socket Connection (ArkTS) (API9)] (https://gitee.com/openharmony/applications_app_samples/tree/master/code/BasicFeature/Connectivity/Socket)
- [UDP Socket (ArkTS) (API9)](https://gitee.com/openharmony/codelabs/tree/master/NetworkManagement/UdpDemoOH)
- [TCP Socket (ArkTS) (API9)](https://gitee.com/openharmony/codelabs/tree/master/NetworkManagement/TcpSocketDemo)
...@@ -37,46 +37,52 @@ The WebSocket connection function is mainly implemented by the WebSocket module. ...@@ -37,46 +37,52 @@ The WebSocket connection function is mainly implemented by the WebSocket module.
5. Close the WebSocket connection if it is no longer needed. 5. Close the WebSocket connection if it is no longer needed.
```js ```js
import webSocket from '@ohos.net.webSocket'; import webSocket from '@ohos.net.webSocket';
var defaultIpAddress = "ws://"; var defaultIpAddress = "ws://";
let ws = webSocket.createWebSocket(); let ws = webSocket.createWebSocket();
ws.on('open', (err, value) => { ws.on('open', (err, value) => {
console.log("on open, status:" + JSON.stringify(value)); console.log("on open, status:" + JSON.stringify(value));
// When receiving the on('open') event, the client can use the send() API to communicate with the server. // When receiving the on('open') event, the client can use the send() API to communicate with the server.
ws.send("Hello, server!", (err, value) => { ws.send("Hello, server!", (err, value) => {
if (!err) { if (!err) {
console.log("Message sent successfully"); console.log("Message sent successfully");
} else { } else {
console.log("Failed to send the message. Err:" + JSON.stringify(err)); console.log("Failed to send the message. Err:" + JSON.stringify(err));
} }
}); });
}); });
ws.on('message', (err, value) => { ws.on('message', (err, value) => {
console.log("on message, message:" + value); console.log("on message, message:" + value);
// When receiving the `bye` message (the actual message name may differ) from the server, the client proactively disconnects from the server. // When receiving the `bye` message (the actual message name may differ) from the server, the client proactively disconnects from the server.
if (value === 'bye') { if (value === 'bye') {
ws.close((err, value) => { ws.close((err, value) => {
if (!err) { if (!err) {
console.log("Connection closed successfully"); console.log("Connection closed successfully");
} else { } else {
console.log("Failed to close the connection. Err: " + JSON.stringify(err)); console.log("Failed to close the connection. Err: " + JSON.stringify(err));
} }
}); });
} }
}); });
ws.on('close', (err, value) => { ws.on('close', (err, value) => {
console.log("on close, code is " + value.code + ", reason is " + value.reason); console.log("on close, code is " + value.code + ", reason is " + value.reason);
}); });
ws.on('error', (err) => { ws.on('error', (err) => {
console.log("on error, error:" + JSON.stringify(err)); console.log("on error, error:" + JSON.stringify(err));
}); });
ws.connect(defaultIpAddress, (err, value) => { ws.connect(defaultIpAddress, (err, value) => {
if (!err) { if (!err) {
console.log("Connected successfully"); console.log("Connected successfully");
} else { } else {
console.log("Connection failed. Err:" + JSON.stringify(err)); console.log("Connection failed. Err:" + JSON.stringify(err));
} }
}); });
``` ```
## Samples
The following samples are provided to help you better understand how to develop WebSocket connection features:
- [`WebSocket`: WebSocket (ArkTS) (API9)](https://gitee.com/openharmony/applications_app_samples/tree/master/code/BasicFeature/Connectivity/WebSocket)
...@@ -21,13 +21,13 @@ The key-value (KV) database stores data in the form of KV pairs. You can use KV ...@@ -21,13 +21,13 @@ The key-value (KV) database stores data in the form of KV pairs. You can use KV
The following table lists the APIs used for KV data persistence. Most of the APIs are executed asynchronously, using a callback or promise to return the result. The following table uses the callback-based APIs as an example. For more information about the APIs, see [Distributed KV Store](../reference/apis/js-apis-distributedKVStore.md). The following table lists the APIs used for KV data persistence. Most of the APIs are executed asynchronously, using a callback or promise to return the result. The following table uses the callback-based APIs as an example. For more information about the APIs, see [Distributed KV Store](../reference/apis/js-apis-distributedKVStore.md).
| API| Description| | API| Description|
| -------- | -------- | | -------- | -------- |
| createKVManager(config: KVManagerConfig): KVManager | Creates a **KvManager** instance to manage database objects.| | createKVManager(config: KVManagerConfig): KVManager | Creates a **KvManager** instance to manage database objects.|
| getKVStore&lt;T&gt;(storeId: string, options: Options, callback: AsyncCallback&lt;T&gt;): void | Creates and obtains a KV store of the specified type.| | getKVStore&lt;T&gt;(storeId: string, options: Options, callback: AsyncCallback&lt;T&gt;): void | Creates and obtains a KV store of the specified type.|
| put(key: string, value: Uint8Array\|string\|number\|boolean, callback: AsyncCallback&lt;void&gt;): void | Adds a KV pair of the specified type to this KV store.| | put(key: string, value: Uint8Array\|string\|number\|boolean, callback: AsyncCallback&lt;void&gt;): void | Adds a KV pair of the specified type to this KV store.|
| get(key: string, callback: AsyncCallback&lt;Uint8Array\|string\|boolean\|number&gt;): void | Obtains the value of the specified key.| | get(key: string, callback: AsyncCallback&lt;Uint8Array\|string\|boolean\|number&gt;): void | Obtains the value of the specified key.|
| delete(key: string, callback: AsyncCallback&lt;void&gt;): void | Deletes a KV pair based on the specified key.| | delete(key: string, callback: AsyncCallback&lt;void&gt;): void | Deletes a KV pair based on the specified key.|
## How to Develop ## How to Develop
...@@ -35,10 +35,9 @@ The following table lists the APIs used for KV data persistence. Most of the API ...@@ -35,10 +35,9 @@ The following table lists the APIs used for KV data persistence. Most of the API
1. Create a **KvManager** instance to manage database objects. 1. Create a **KvManager** instance to manage database objects.
Example: Example:
Stage model: Stage model:
```js ```js
// Import the module. // Import the module.
import distributedKVStore from '@ohos.data.distributedKVStore'; import distributedKVStore from '@ohos.data.distributedKVStore';
...@@ -69,7 +68,7 @@ The following table lists the APIs used for KV data persistence. Most of the API ...@@ -69,7 +68,7 @@ The following table lists the APIs used for KV data persistence. Most of the API
FA model: FA model:
```js ```js
// Import the module. // Import the module.
import distributedKVStore from '@ohos.data.distributedKVStore'; import distributedKVStore from '@ohos.data.distributedKVStore';
...@@ -93,14 +92,13 @@ The following table lists the APIs used for KV data persistence. Most of the API ...@@ -93,14 +92,13 @@ The following table lists the APIs used for KV data persistence. Most of the API
``` ```
2. Create and obtain a KV store. 2. Create and obtain a KV store.
Example: Example:
```js ```js
try { try {
const options = { const options = {
createIfMissing: true, // Whether to create a KV store when the database file does not exist. By default, a KV store is created. createIfMissing: true, // Whether to create a KV store when the database file does not exist. By default, a KV store is created.
createIfMissing: true, // Whether to encrypt database files. By default, database files are not encrypted. encrypt: false, // Whether to encrypt the KV store. By default, KV stores are not encrypted.
backup: false, // Whether to back up database files. By default, the database files are backed up. backup: false, // Whether to back up database files. By default, the database files are backed up.
autoSync: true, // Whether to automatically synchronize database files. The value **true** means to automatically synchronize database files; the value **false** (default) means the opposite. autoSync: true, // Whether to automatically synchronize database files. The value **true** means to automatically synchronize database files; the value **false** (default) means the opposite.
kvStoreType: distributedKVStore.KVStoreType.SINGLE_VERSION, // Type of the KV store to create. By default, a device KV store is created. kvStoreType: distributedKVStore.KVStoreType.SINGLE_VERSION, // Type of the KV store to create. By default, a device KV store is created.
...@@ -121,9 +119,8 @@ The following table lists the APIs used for KV data persistence. Most of the API ...@@ -121,9 +119,8 @@ The following table lists the APIs used for KV data persistence. Most of the API
``` ```
3. Use **put()** to add data to the KV store. 3. Use **put()** to add data to the KV store.
Example: Example:
```js ```js
const KEY_TEST_STRING_ELEMENT = 'key_test_string'; const KEY_TEST_STRING_ELEMENT = 'key_test_string';
const VALUE_TEST_STRING_ELEMENT = 'value_test_string'; const VALUE_TEST_STRING_ELEMENT = 'value_test_string';
...@@ -145,9 +142,8 @@ The following table lists the APIs used for KV data persistence. Most of the API ...@@ -145,9 +142,8 @@ The following table lists the APIs used for KV data persistence. Most of the API
> The **put()** method adds a KV pair if the specified key does not exists and changes the value if the the specified key already exists. > The **put()** method adds a KV pair if the specified key does not exists and changes the value if the the specified key already exists.
4. Use **get()** to obtain the value of a key. 4. Use **get()** to obtain the value of a key.
Example: Example:
```js ```js
const KEY_TEST_STRING_ELEMENT = 'key_test_string'; const KEY_TEST_STRING_ELEMENT = 'key_test_string';
const VALUE_TEST_STRING_ELEMENT = 'value_test_string'; const VALUE_TEST_STRING_ELEMENT = 'value_test_string';
...@@ -172,9 +168,8 @@ The following table lists the APIs used for KV data persistence. Most of the API ...@@ -172,9 +168,8 @@ The following table lists the APIs used for KV data persistence. Most of the API
``` ```
5. Use **delete()** to delete the data of the specified key. 5. Use **delete()** to delete the data of the specified key.
Example: Example:
```js ```js
const KEY_TEST_STRING_ELEMENT = 'key_test_string'; const KEY_TEST_STRING_ELEMENT = 'key_test_string';
const VALUE_TEST_STRING_ELEMENT = 'value_test_string'; const VALUE_TEST_STRING_ELEMENT = 'value_test_string';
......
...@@ -79,14 +79,14 @@ When data is added, deleted, or modified, a notification is sent to the subscrib ...@@ -79,14 +79,14 @@ When data is added, deleted, or modified, a notification is sent to the subscrib
The following table lists the APIs for cross-device data synchronization of the single KV store. Most of the APIs are executed asynchronously, using a callback or promise to return the result. The following table uses the callback-based APIs as an example. For more information about the APIs, see [Distributed KV Store](../reference/apis/js-apis-distributedKVStore.md). The following table lists the APIs for cross-device data synchronization of the single KV store. Most of the APIs are executed asynchronously, using a callback or promise to return the result. The following table uses the callback-based APIs as an example. For more information about the APIs, see [Distributed KV Store](../reference/apis/js-apis-distributedKVStore.md).
| API| Description| | API| Description|
| -------- | -------- | | -------- | -------- |
| createKVManager(config: KVManagerConfig): KVManager | Creates a **KvManager** instance to manage database objects.| | createKVManager(config: KVManagerConfig): KVManager | Creates a **KvManager** instance to manage database objects.|
| getKVStore&lt;T&gt;(storeId: string, options: Options, callback: AsyncCallback&lt;T&gt;): void | Creates and obtains a KV store of the specified type.| | getKVStore&lt;T&gt;(storeId: string, options: Options, callback: AsyncCallback&lt;T&gt;): void | Creates and obtains a KV store of the specified type.|
| put(key: string, value: Uint8Array\|string\|number\|boolean, callback: AsyncCallback&lt;void&gt;): void | Inserts and updates data.| | put(key: string, value: Uint8Array\|string\|number\|boolean, callback: AsyncCallback&lt;void&gt;): void | Inserts and updates data.|
| on(event: 'dataChange', type: SubscribeType, listener: Callback&lt;ChangeNotification&gt;): void | Subscribes to data changes in the KV store.| | on(event: 'dataChange', type: SubscribeType, listener: Callback&lt;ChangeNotification&gt;): void | Subscribes to data changes in the KV store.|
| get(key: string, callback: AsyncCallback&lt;boolean \| string \| number \| Uint8Array&gt;): void | Queries the value of the specified key.| | get(key: string, callback: AsyncCallback&lt;boolean \| string \| number \| Uint8Array&gt;): void | Queries the value of the specified key.|
| sync(deviceIds: string[], mode: SyncMode, delayMs?: number): void | Triggers a manual synchronization of the KV store.| | sync(deviceIds: string[], mode: SyncMode, delayMs?: number): void | Triggers a manual synchronization of the KV store.|
## How to Develop ## How to Develop
...@@ -100,7 +100,7 @@ The following uses a single KV store as an example to describe how to implement ...@@ -100,7 +100,7 @@ The following uses a single KV store as an example to describe how to implement
> The data on a device can be synchronized only to the devices whose data security labels are not higher than the security level of the device. For details, see [Access Control Mechanism in Cross-Device Synchronization](sync-app-data-across-devices-overview.md#access-control-mechanism-in-cross-device-synchronization). > The data on a device can be synchronized only to the devices whose data security labels are not higher than the security level of the device. For details, see [Access Control Mechanism in Cross-Device Synchronization](sync-app-data-across-devices-overview.md#access-control-mechanism-in-cross-device-synchronization).
1. Import the module. 1. Import the module.
```js ```js
import distributedKVStore from '@ohos.data.distributedKVStore'; import distributedKVStore from '@ohos.data.distributedKVStore';
``` ```
...@@ -115,7 +115,7 @@ The following uses a single KV store as an example to describe how to implement ...@@ -115,7 +115,7 @@ The following uses a single KV store as an example to describe how to implement
1. Create a **kvManagerConfig** object based on the application context. 1. Create a **kvManagerConfig** object based on the application context.
2. Create a **KvManager** instance. 2. Create a **KvManager** instance.
```js ```js
// Obtain the context of the stage model. // Obtain the context of the stage model.
import UIAbility from '@ohos.app.ability.UIAbility'; import UIAbility from '@ohos.app.ability.UIAbility';
...@@ -152,7 +152,7 @@ The following uses a single KV store as an example to describe how to implement ...@@ -152,7 +152,7 @@ The following uses a single KV store as an example to describe how to implement
1. Declare the ID of the distributed KV store to create. 1. Declare the ID of the distributed KV store to create.
2. Disable the auto synchronization function (**autoSync:false**) to facilitate subsequent verification of the synchronization function. If synchronization is required, call the **sync()** interface. 2. Disable the auto synchronization function (**autoSync:false**) to facilitate subsequent verification of the synchronization function. If synchronization is required, call the **sync()** interface.
```js ```js
try { try {
const options = { const options = {
...@@ -179,7 +179,7 @@ The following uses a single KV store as an example to describe how to implement ...@@ -179,7 +179,7 @@ The following uses a single KV store as an example to describe how to implement
``` ```
5. Subscribe to changes of distributed data. 5. Subscribe to changes of distributed data.
```js ```js
try { try {
kvStore.on('dataChange', distributedKVStore.SubscribeType.SUBSCRIBE_TYPE_ALL, (data) => { kvStore.on('dataChange', distributedKVStore.SubscribeType.SUBSCRIBE_TYPE_ALL, (data) => {
...@@ -195,7 +195,7 @@ The following uses a single KV store as an example to describe how to implement ...@@ -195,7 +195,7 @@ The following uses a single KV store as an example to describe how to implement
1. Construct the key and value to be written to the single KV store. 1. Construct the key and value to be written to the single KV store.
2. Write KV pairs to the single KV store. 2. Write KV pairs to the single KV store.
```js ```js
const KEY_TEST_STRING_ELEMENT = 'key_test_string'; const KEY_TEST_STRING_ELEMENT = 'key_test_string';
const VALUE_TEST_STRING_ELEMENT = 'value_test_string'; const VALUE_TEST_STRING_ELEMENT = 'value_test_string';
...@@ -217,7 +217,7 @@ The following uses a single KV store as an example to describe how to implement ...@@ -217,7 +217,7 @@ The following uses a single KV store as an example to describe how to implement
1. Construct the key to be queried from the single KV store. 1. Construct the key to be queried from the single KV store.
2. Query data from the single KV store. 2. Query data from the single KV store.
```js ```js
const KEY_TEST_STRING_ELEMENT = 'key_test_string'; const KEY_TEST_STRING_ELEMENT = 'key_test_string';
const VALUE_TEST_STRING_ELEMENT = 'value_test_string'; const VALUE_TEST_STRING_ELEMENT = 'value_test_string';
...@@ -249,7 +249,7 @@ The following uses a single KV store as an example to describe how to implement ...@@ -249,7 +249,7 @@ The following uses a single KV store as an example to describe how to implement
> >
> If manual synchronization is used, **deviceIds** is obtained by using [devManager.getTrustedDeviceListSync](../reference/apis/js-apis-device-manager.md#gettrusteddevicelistsync). The APIs of the **deviceManager** module are all system interfaces and available only to system applications. > If manual synchronization is used, **deviceIds** is obtained by using [devManager.getTrustedDeviceListSync](../reference/apis/js-apis-device-manager.md#gettrusteddevicelistsync). The APIs of the **deviceManager** module are all system interfaces and available only to system applications.
```js ```js
import deviceManager from '@ohos.distributedHardware.deviceManager'; import deviceManager from '@ohos.distributedHardware.deviceManager';
......
...@@ -3,7 +3,7 @@ ...@@ -3,7 +3,7 @@
## When to Use ## When to Use
When creating a data table, you can set the table to support cross-device access. You can also use APIs to move the data to be accessed across devices to a distributed data. You can synchronize the application data in a local RDB store on a device to other divices that form a Super Device.
## Basic Concepts ## Basic Concepts
...@@ -51,14 +51,14 @@ When data is added, deleted, or modified, a notification is sent to the subscrib ...@@ -51,14 +51,14 @@ When data is added, deleted, or modified, a notification is sent to the subscrib
The following table lists the APIs for cross-device data synchronization of RDB stores. Most of the APIs are executed asynchronously, using a callback or promise to return the result. The following table uses the callback-based APIs as an example. For more information about the APIs, see [RDB Store](../reference/apis/js-apis-data-relationalStore.md). The following table lists the APIs for cross-device data synchronization of RDB stores. Most of the APIs are executed asynchronously, using a callback or promise to return the result. The following table uses the callback-based APIs as an example. For more information about the APIs, see [RDB Store](../reference/apis/js-apis-data-relationalStore.md).
| API| Description| | API| Description|
| -------- | -------- | | -------- | -------- |
| setDistributedTables(tables: Array&lt;string&gt;, callback: AsyncCallback&lt;void&gt;): void | Sets the distributed tables to be synchronized.| | setDistributedTables(tables: Array&lt;string&gt;, callback: AsyncCallback&lt;void&gt;): void | Sets the distributed tables to be synchronized.|
| sync(mode: SyncMode, predicates: RdbPredicates, callback: AsyncCallback&lt;Array&lt;[string, number]&gt;&gt;): void | Synchronizes data across devices.| | sync(mode: SyncMode, predicates: RdbPredicates, callback: AsyncCallback&lt;Array&lt;[string, number]&gt;&gt;): void | Synchronizes data across devices.|
| on(event: 'dataChange', type: SubscribeType, observer: Callback&lt;Array&lt;string&gt;&gt;): void | Subscribes to changes in the distributed data.| | on(event: 'dataChange', type: SubscribeType, observer: Callback&lt;Array&lt;string&gt;&gt;): void | Subscribes to changes in the distributed data.|
| off(event:'dataChange', type: SubscribeType, observer: Callback&lt;Array&lt;string&gt;&gt;): void | Unsubscribe from changes in the distributed data.| | off(event:'dataChange', type: SubscribeType, observer: Callback&lt;Array&lt;string&gt;&gt;): void | Unsubscribe from changes in the distributed data.|
| obtainDistributedTableName(device: string, table: string, callback: AsyncCallback&lt;string&gt;): void; | Obtains the table name on the specified device based on the local table name.| | obtainDistributedTableName(device: string, table: string, callback: AsyncCallback&lt;string&gt;): void; | Obtains the table name on the specified device based on the local table name.|
| remoteQuery(device: string, table: string, predicates: RdbPredicates, columns: Array&lt;string&gt; , callback: AsyncCallback&lt;ResultSet&gt;): void | Queries data from the RDB store of a remote device based on specified conditions.| | remoteQuery(device: string, table: string, predicates: RdbPredicates, columns: Array&lt;string&gt; , callback: AsyncCallback&lt;ResultSet&gt;): void | Queries data from the RDB store of a remote device based on specified conditions.|
## How to Develop ## How to Develop
...@@ -68,7 +68,7 @@ The following table lists the APIs for cross-device data synchronization of RDB ...@@ -68,7 +68,7 @@ The following table lists the APIs for cross-device data synchronization of RDB
> The data on a device can be synchronized only to the devices whose data security labels are not higher than the security level of the device. For details, see [Access Control Mechanism in Cross-Device Synchronization](sync-app-data-across-devices-overview.md#access-control-mechanism-in-cross-device-synchronization). > The data on a device can be synchronized only to the devices whose data security labels are not higher than the security level of the device. For details, see [Access Control Mechanism in Cross-Device Synchronization](sync-app-data-across-devices-overview.md#access-control-mechanism-in-cross-device-synchronization).
1. Import the module. 1. Import the module.
```js ```js
import relationalStore from '@ohos.data.relationalStore'; import relationalStore from '@ohos.data.relationalStore';
``` ```
...@@ -79,7 +79,7 @@ The following table lists the APIs for cross-device data synchronization of RDB ...@@ -79,7 +79,7 @@ The following table lists the APIs for cross-device data synchronization of RDB
2. Display a dialog box to ask authorization from the user when the application is started for the first time. For details, see [Requesting User Authorization](../security/accesstoken-guidelines.md#requesting-user-authorization). 2. Display a dialog box to ask authorization from the user when the application is started for the first time. For details, see [Requesting User Authorization](../security/accesstoken-guidelines.md#requesting-user-authorization).
3. Create an RDB store and set a table for distributed synchronization. 3. Create an RDB store and set a table for distributed synchronization.
```js ```js
const STORE_CONFIG = { const STORE_CONFIG = {
name: 'RdbTest.db', // Database file name. name: 'RdbTest.db', // Database file name.
...@@ -95,7 +95,7 @@ The following table lists the APIs for cross-device data synchronization of RDB ...@@ -95,7 +95,7 @@ The following table lists the APIs for cross-device data synchronization of RDB
``` ```
4. Synchronize data across devices. After **sync()** is called to trigger a synchronization, data is synchronized from the local device to all other devices on the network. 4. Synchronize data across devices. After **sync()** is called to trigger a synchronization, data is synchronized from the local device to all other devices on the network.
```js ```js
// Construct the predicate object for synchronizing the distributed table. // Construct the predicate object for synchronizing the distributed table.
let predicates = new relationalStore.RdbPredicates('EMPLOYEE'); let predicates = new relationalStore.RdbPredicates('EMPLOYEE');
...@@ -114,7 +114,7 @@ The following table lists the APIs for cross-device data synchronization of RDB ...@@ -114,7 +114,7 @@ The following table lists the APIs for cross-device data synchronization of RDB
``` ```
5. Subscribe to changes in the distributed data. The data synchronization triggers the **observer** callback registered in **on()**. The input parameter of the callback is the ID of the device whose data changes. 5. Subscribe to changes in the distributed data. The data synchronization triggers the **observer** callback registered in **on()**. The input parameter of the callback is the ID of the device whose data changes.
```js ```js
let observer = function storeObserver(devices) { let observer = function storeObserver(devices) {
for (let i = 0; i < devices.length; i++) { for (let i = 0; i < devices.length; i++) {
...@@ -144,7 +144,7 @@ The following table lists the APIs for cross-device data synchronization of RDB ...@@ -144,7 +144,7 @@ The following table lists the APIs for cross-device data synchronization of RDB
> >
> **deviceIds** is obtained by using [devManager.getTrustedDeviceListSync](../reference/apis/js-apis-device-manager.md#gettrusteddevicelistsync). The APIs of the **deviceManager** module are all system interfaces and available only to system applications. > **deviceIds** is obtained by using [devManager.getTrustedDeviceListSync](../reference/apis/js-apis-device-manager.md#gettrusteddevicelistsync). The APIs of the **deviceManager** module are all system interfaces and available only to system applications.
```js ```js
// Obtain device IDs. // Obtain device IDs.
import deviceManager from '@ohos.distributedHardware.deviceManager'; import deviceManager from '@ohos.distributedHardware.deviceManager';
......
...@@ -36,14 +36,4 @@ Strong consistency has high requirements on distributed data management and may ...@@ -36,14 +36,4 @@ Strong consistency has high requirements on distributed data management and may
## Access Control Mechanism in Cross-Device Synchronization ## Access Control Mechanism in Cross-Device Synchronization
In the application data synchronization across devices, data access is controlled based on the device level and [data security label](access-control-by-device-and-data-level.md#data-security-labels). In principle, data can be synchronized only to the devices whose data security labels are not higher than the device's security level. The access control matrix is as follows: When data is synchronized across devices, access control is performed based on the device level and data security label. For details, see [Access Control Mechanism in Cross-Device Synchronization](access-control-by-device-and-data-level.md#access-control-mechanism-in-cross-device-synchronization).
|Device Security Level|Data Security Labels of the Synchornizable Device|
|---|---|
|SL1|S1|
|SL2|S1 to S2|
|SL3|S1 to S3|
|SL4|S1 to S4|
|SL5|S1 to S4|
For example, the security level of development boards RK3568 and Hi3516 is SL1. The database with data security label S1 can be synchronized with RK3568 and Hi3516, but the database with database labels S2-S4 cannot.
...@@ -6,4 +6,7 @@ ...@@ -6,4 +6,7 @@
- [HiLog Development (Native)](hilog-guidelines.md) - [HiLog Development (Native)](hilog-guidelines.md)
- Error Management - Error Management
- [Development of Error Manager](errormanager-guidelines.md) - [Development of Error Manager](errormanager-guidelines.md)
- [Development of Application Recovery](apprecovery-guidelines.md) - [Development of Application Recovery](apprecovery-guidelines.md)
\ No newline at end of file - Log Management
- [Application Freeze (appfreeze) Log Analysis](appfreeze-guidelines.md)
- [Process Crash (cppcrash) Log Analysis](cppcrash-guidelines.md)
# Application Freeze (appfreeze) Log Analysis
## Introduction
Application freeze (appfreeze) means that an application does not respond to user operations (for example, clicking) within a given period of time. OpenHarmony provides a mechanism for detecting appfreeze faults and generates appfreeze logs for fault analysis.
> NOTE
>
> This guide applies only to applications in the stage model.
> Before using this guide, you must have basic knowledge about the JS applications, C++ program stacks, and application-related subsystems.
## How to Obtain
appfreeze log is a type of fault logs managed together with the native process crash, JS application crash, and system process crash logs . You can obtain the log in any of the following ways.
### Collecting Logs by Using Shell
appfreeze logs start with **appfreeze-** in **/data/log/faultlog/faultlogger/**.
The log files are named in the format of **appfreeze-application package name-application UID-time (seconds level)**.
![appfreeze_20230308145160](figures/appfreeze_20230308145160.png)
### Collecting Logs by Using DevEco Studio
DevEco Studio collects device fault logs and saves them to FaultLog.
The logs are displayed by the bundle name, fault, and time.
![appfreeze_20230308145161](figures/appfreeze_20230308145161.png)
### Collecting Logs by Using faultLogger APIs
The FaultLogger module provides APIs to query various fault information. For details, see [@ohos.faultLogger](../reference/apis/js-apis-faultLogger.md).
## appfreeze Detection
Currently, appfreeze detection supports the fault types listed in the following table.
| Fault Type| Description|
| -------- | -------- |
| THREAD_BLOCK_6S | The application main thread times out due to a suspension.|
| APPLICATION_BLOCK_INPUT | The user input response times out.|
| LIFECYCLE_TIMEOUT | Ability lifecycle switching times out.|
| APP_LIFECYCLE_TIMEOUT | Application lifecycle switching times out.|
### Application Main Thread Timeout
If this fault occurs, the main thread of the current application is suspended or too many tasks are executed, affecting task execution smoothness and experience.
Such a fault can be detected as follows: The watchdog thread of the application periodically inserts an activation detection subthread to the main thread and inserts a timeout reporting subthread to its own thread. If activation detection is not executed within 3 seconds, the THREAD_BLOCK_3S event is reported; if activation detection is not executed within 6 seconds, the THREAD_BLOCK_6S event is reported. The two events together form an appfreeze log. The following figure shows the working principle.
![appfreeze_20230308145163](figures/appfreeze_20230308145163.png)
### User Input Response Timeout
This fault affects user experience. If this fault occurs, the system does not respond to a click event within 10 seconds.
Such a fault can be detected as follows: When a user clicks a certain button of the application, the input system sends a click event to the application. If the input system does not receive a response from the application within 10 seconds, a fault event is reported. The following figure shows the working principle.
![appfreeze_20230308145162](figures/appfreeze_20230308145162.png)
### Lifecycle Switching Timeout
This fault refers to an ability lifecycle switching timeout (LIFECYCLE\_TIMEOUT) or an application lifecycle switching timeout (APP\_LIFECYCLE\_TIMEOUT).
The fault occurs during lifecycle switching and affects the switchover between abilities in the current application or the switchover between applications.
Such a fault can be detected as follows: Upon the start of a lifecycle switchover process, the main thread inserts a timeout task to the watchdog thread, and then removes the timeout task when the lifecycle switchover is complete. If the timeout duration expires, a fault event is reported.
![appfreeze_20230308145164](figures/appfreeze_20230308145164.png)
The timeout duration varies according to the lifecycle.
| Lifecycle| Timeout Duration|
| -------- | -------- |
| Load | 10s |
| Terminate | 10s |
| Connect | 3s |
| Disconnect | 0.5s |
| Foreground | 5s |
| Background | 3s |
## appfreeze Log Analysis
To identify the cause of appfreeze, analyze the appfreeze logs together with HiLog logs.
The following example uses main tread suspension as an example to illustrate how to conduct log analysis. You can treat other types of faults in a similar way.
appfreeze logs are divided into several parts, including header information, and general and specific information in the body.
### Log Header Information
| Field| Description|
| -------- | -------- |
| Reason | Reason why the application does not respond. For details, see [appfreeze Detection](#appfreeze-detection).|
| PID | PID of the failed process, which can be used to search for related process information in the log.|
| PACKAGE_NAME | Application package name.|
![appfreeze_20230310105865](figures/appfreeze_20230310105865.png)
### General Information in the Log Body
General information is present in all logs. It contains the fields listed in the following table. You can search for these fields to locate the related information in the log.
| Field| Description|
| -------- | -------- |
| EVENTNAME | One or more fault events that constitute the cause of main thread suspension.|
| TIMESTAMP | Time when the fault event reported. You can narrow down the time range for viewing HiLog logs based on the timeout duration described in [appfreeze Detection](#appfreeze-detection).|
| PID | PID of the failed process, which can be used with the timestamp and timeout duration to search for related process information in the log.|
| PACKAGE_NAME | Application package name.|
| MSG | Dump information or description of the fault.|
| OpenStacktraceCatcher | Stack trace information of the process.|
| BinderCatcher | Information about IPC calls between a process and other system processes, such as the call waiting time.|
| PeerBinder Stacktrace | Information about stack trace of the peer process.|
| cpuusage | CPU usage of the device.|
| memory | Memory usage of the process.|
The following is an example process stack of OpenStacktraceCatcher.
In this example, when the stack surface window sends events through IPC, the process is stuck in the IPC communication phase.
![appfreeze_20230310105869](figures/appfreeze_20230310105869.png)
Example BinderCatcher information:
In the following example, process 1561 sends an IPC request to process 685 but does not receive any response within 10 seconds.
![appfreeze_20230310105868](figures/appfreeze_20230310105868.png)
Example PeerBinder Stacktrace information:
The following example shows the stack information of process 685, which is suspended at the peer end.
![appfreeze_20230310105870](figures/appfreeze_20230310105870.png)
Example CPU usage information:
The following example shows the CPU usage information of the device.
![appfreeze_20230310105871](figures/appfreeze_20230310105871.png)
Example memory usage information:
The following example shows the memory usage information of the process.
![appfreeze_20230310105872](figures/appfreeze_20230310105872.png)
### Specific Information in the Log Body (Application Main Thread Timeout)
According to [Application Main Thread Timeout] (#application-main-thread-timeout), the log in which **Reason** is **THREAD\_BLOCK\_6S** consists of two parts: THREAD\_BLOCK\_3S and THREAD\_BLOCK\_6S. By comparing the two parts, you can determine whether the appfreeze is due to a suspension or an excess number of tasks.
THREAD\_BLOCK\_3S is followed by THREAD\_BLOCK\_6S in the log. You can use the **EVENTNAME** field to search for the locations of the two events in the log.
Both events contain the **MSG** field, which stores information about the processing queue of the main thread when the suspension occurs. Hence, you can view the status of the event processing queue of the main thread at the two time points.
The example log shows that the event carrying **05:06:18.145** in the low-priority queue is being processed, and it is present in both the THREAD_BLOCK_3S and THREAD_BLOCK_6S. This indicates that the main thread suspension is not caused by an excess number of tasks.
Because THREAD_BLOCK_6S indicates a main thread suspension, you only need to analyze the stack information of the main thread (the ID of the main thread is the same as the process ID). In the example log, the main thread stack is run in the JS through ArkUI and therefore it can be concluded that the suspension occurs in the JS. Because stack is present in both THREAD_BLOCK_3S and THREAD_BLOCK_6S in the same position, the JS suspension is not caused by an excess number of tasks.
THREAD_BLOCK_3S:
![appfreeze_20230310105866](figures/appfreeze_20230310105866.png)
THREAD_BLOCK_6S:
![appfreeze_20230310105867](figures/appfreeze_20230310105867.png)
Then, you can check for the code segment being executed on the application side based on the HiLog log.
Generally, you can view the [general information in the log body](#general-information-in-the-log-body) to check for the cause of the suspension, for example, IPC suspension, high CPU usage, memory leakage, or high memory usage.
### Specific Information in the Log Body (User Input Response Timeout)
If **Reason** is **APPLICATION\_BLOCK\_INPUT**, no response is received within 10 seconds after a user click.
You can find the event description in **MSG**.
For details, see [General Information in the Log Body](#general-information-in-the-log-body). Note that there is a high probability that the main thread is suspended in the case of no response to the user input. You can compare the stack and BinderCatcher information in two log records for further analysis. If there is no log record indicating a main thread suspension, a large number of other events may exist before the input event. This may not cause a main thread suspension but can probably result in no response to user input.
### Specific Information in the Log Body (Lifecycle Switching Timeout)
For a lifecycle switching timeout, **Reason** can be **LIFECYCLE\_TIMEOUT** or **APP\_LIFECYCLE\_TIMEOUT**.
**LIFECYCLE\_TIMEOUT** indicates a lifecycle switching timeout at the ability level, and **APP\_LIFECYCLE\_TIMEOUT** indicates a lifecycle switching timeout at the application level.
MSG indicates the lifecycle that encounters a timeout.
In this example, **LIFECYCLE\_TIMEOUT** indicates that the timeout occurs during switching of the ability to the background, and **APP\_LIFECYCLE\_TIMEOUT** indicates that the timeout occurs in the application termination phase. You can locate related HiLog logs according to the timeout duration described in [Lifecycle Switching Timeout] (#lifecycle-switching-timeout).
LIFECYCLE_TIMEOUT:
![appfreeze_20230310105873](figures/appfreeze_20230310105873.png)
APP_LIFECYCLE_TIMEOUT:
![appfreeze_20230310105874](figures/appfreeze_20230310105874.png)
For details about other log information, see [General Information in the Log Body](#general-information-in-the-log-body). Note that there is a high probability that the main thread is suspended during lifecycle switching. You can compare the stack and BinderCatcher information in two log records for further analysis.
...@@ -5,48 +5,29 @@ ...@@ -5,48 +5,29 @@
During application running, some unexpected behaviors are inevitable. For example, unprocessed exceptions and errors are thrown, and the call or running constraints of the recovery framework are violated. During application running, some unexpected behaviors are inevitable. For example, unprocessed exceptions and errors are thrown, and the call or running constraints of the recovery framework are violated.
Process exit is treated as the default exception handling method. However, if user data is generated during application use, process exit may interrupt user operations and cause data loss. Process exit is treated as the default exception handling method. However, if user data is generated during application use, process exit may interrupt user operations and cause data loss.
Application recovery helps to restore the application state and save temporary data upon next startup in the case of an abnormal process exit, thus providing more consistent user experience. The application state includes two parts, namely, the page stack of the and the data saved in **onSaveState**. In this way, application recovery APIs may help you save temporary data, restart an application after it exits, and restore its status and data, which deliver a better user experience.
In API version 9, application recovery is supported only for a single ability of the application developed using the stage model. Application state saving and automatic restart are performed when a JsError occurs. Currently, the APIs support only the development of an application that adopts the stage model, single process, and single ability.
In API version 10, application recovery is applicable to multiple abilities of an application developed using the stage model. Application state storage and restore are performed when an AppFreeze occurs. If an application is killed in control mode, the application state will be restored upon next startup.
## Available APIs ## Available APIs
The application recovery APIs are provided by the **appRecovery** module, which can be imported via **import**. For details, see [Development Example](#development-example). The application recovery APIs are provided by the **appRecovery** module, which can be imported via **import**. For details, see [Development Example](#development-example). This document describes behaviors of APIs in API version 9, and the content will update with changes.
### Available APIs ### Available APIs
| API | Description | | API | Description |
| ------------------------------------------------------------ | ---------------------------------------------------- | | ------------------------------------------------------------ | ---------------------------------------------------- |
| enableAppRecovery(restart?: RestartFlag, saveOccasion?: SaveOccasionFlag, saveMode?: SaveModeFlag) : void;<sup>9+</sup> | Enables application recovery. After this API is called, the first ability that is displayed when the application is started from the initiator can be restored.| | enableAppRecovery(restart?: RestartFlag, saveOccasion?: SaveOccasionFlag, saveMode?: SaveModeFlag) : void; | Enables the application recovery function.|
| saveAppState(): boolean;<sup>9+</sup> | Saves the state of the ability that supports recovery in the current application.| | saveAppState(): boolean; | Saves the ability status of an application. |
| restartApp(): void;<sup>9+</sup> | Restarts the current process and starts the ability specified by **setRestartWant**. If no ability is specified, a foreground ability that supports recovery is restarted.| | restartApp(): void; | Restarts the current process. If there is saved ability status, it will be passed to the **want** parameter's **wantParam** attribute of the **onCreate** lifecycle callback of the ability.|
| saveAppState(context?: UIAbilityContext): boolean;<sup>10+</sup> | Saves the ability state specified by **Context**.|
| setRestartWant(want: Want): void;<sup>10+</sup> | Sets the abilities to restart when **restartApp** is actively called and **RestartFlag** is not **NO_RESTART**. The abilities must be under the same bundle name and must be a **UiAbility**.|
No error will be thrown if the preceding APIs are used in the troubleshooting scenario. The following are some notes on API usage: The APIs are used for troubleshooting and do not return any exception. Therefore, you need to be familiar with when they are used.
**enableAppRecovery**: This API should be called during application initialization. For example, you can call this API in **onCreate** of **AbilityStage**. For details, see [Parameter Description](../reference/apis/js-apis-app-ability-appRecovery.md). **enableAppRecovery**: This API should be called during application initialization. For example, you can call this API in **onCreate** of **AbilityStage**. For details, see [Parameter Description](../reference/apis/js-apis-app-ability-appRecovery.md).
**saveAppState**: After this API is called, the recovery framework invokes **onSaveState** for all abilities that support recovery in the current process. If you choose to save data in **onSaveState**, the related data and ability page stack are persistently stored in the local cache of the application. To save data of the specified ability, you need to specify the context corresponding to that ability. **saveAppState**: After this API is called, the framework calls back **onSaveState** of the ability. If data saving is accepted in this API, relevant data and the page stack of the ability are persisted to the local cache of the application.
**setRestartWant**: This API specifies the ability to be restarted by **appRecovery**.
**restartApp**: After this API is called, the recovery framework kills the current process and restarts the ability specified by **setRestartWant**, with **APP_RECOVERY** set as the startup cause. In API version 9 and scenarios where an ability is not specified by **setRestartWant**, the last foreground ability that supports recovery is started. If the no foreground ability supports recovery, the application crashes. If a saved state is available for the restarted ability, the saved state is passed as the **wantParam** attribute in the **want** parameter of the ability's **onCreate** callback.
### Application State Management
Since API version 10, application recovery is not limited to automatic restart in the case of an exception. Therefore, you need to understand when the application will load the saved state.
If the last exit of an application is not initiated by a user and a saved state is available for recovery, the startup reason is set to **APP_RECOVERY** when the application is started by the user next time, and the recovery state of the application is cleared.
The application recovery status flag is set when **saveAppState** is actively or passively called. The flag is cleared when the application exits normally or the saved state is consumed. (A normal exit is usually triggered by pressing the back key or clearing recent tasks.)
![Application recovery status management](./figures/application_recovery_status_management.png)
### Application State Saving and Restore
API version 10 or later supports saving of the application state when an application is suspended. If a JsError occurs, **onSaveState** is called in the main thread. If an AppFreeze occurs, however, the main thread may be suspended, and therefore **onSaveState** is called in a non-main thread. The following figure shows the main service flow.
![Application recovery from the freezing state](./figures/application_recovery_from_freezing.png) **restartApp**: After this API is called, the framework kills the current application process and restarts the ability in the foreground, with **APP_RECOVERY** specified as the startup cause.
When the application is suspended, the callback is not executed in the JS thread. Therefore, you are advised not to use the imported dynamic Native library or access the **thread_local** object created by the main thread in the code of the **onSaveState** callback.
### Framework Fault Management ### Framework Fault Management
...@@ -59,7 +40,9 @@ Fault management is an important way for applications to deliver a better user e ...@@ -59,7 +40,9 @@ Fault management is an important way for applications to deliver a better user e
- Fault query is the process of calling APIs of [faultLogger](../reference/apis/js-apis-faultLogger.md) to obtain the fault information. - Fault query is the process of calling APIs of [faultLogger](../reference/apis/js-apis-faultLogger.md) to obtain the fault information.
The figure below does not illustrate the time when [faultLogger](../reference/apis/js-apis-faultLogger.md) is called. You can refer to the [LastExitReason](../reference/apis/js-apis-app-ability-abilityConstant.md#abilityconstantlastexitreason) passed during application initialization to determine whether to call [faultLogger](../reference/apis/js-apis-faultLogger.md) to query information about the previous fault. The figure below does not illustrate the time when [faultLogger](../reference/apis/js-apis-faultLogger.md) is called. You can refer to the [LastExitReason](../reference/apis/js-apis-app-ability-abilityConstant.md#abilityconstantlastexitreason) passed during application initialization to determine whether to call [faultLogger](../reference/apis/js-apis-faultLogger.md) to query information about the previous fault.
![Fault rectification process](./figures/fault_rectification.png) ![Fault rectification process](./figures/fault_rectification.png)
It is recommended that you call [errorManager](../reference/apis/js-apis-app-ability-errorManager.md) to handle the exception. After the processing is complete, you can call the **saveAppState** API and restart the application. It is recommended that you call [errorManager](../reference/apis/js-apis-app-ability-errorManager.md) to handle the exception. After the processing is complete, you can call the **saveAppState** API and restart the application.
If you do not register [ErrorObserver](../reference/apis/js-apis-inner-application-errorObserver.md) or enable application recovery, the application process will exit according to the default processing logic of the system. Users can restart the application from the home screen. If you do not register [ErrorObserver](../reference/apis/js-apis-inner-application-errorObserver.md) or enable application recovery, the application process will exit according to the default processing logic of the system. Users can restart the application from the home screen.
If you have enabled application recovery, the recovery framework first checks whether application state saving is supported and whether the application state saving is enabled. If so, the recovery framework invokes [onSaveState](../reference/apis/js-apis-app-ability-uiAbility.md#uiabilityonsavestate) of the [Ability](../reference/apis/js-apis-app-ability-uiAbility.md). Finally, the application is restarted. If you have enabled application recovery, the recovery framework first checks whether application state saving is supported and whether the application state saving is enabled. If so, the recovery framework invokes [onSaveState](../reference/apis/js-apis-app-ability-uiAbility.md#uiabilityonsavestate) of the [Ability](../reference/apis/js-apis-app-ability-uiAbility.md). Finally, the application is restarted.
...@@ -71,7 +54,7 @@ Common fault types include JavaScript application crash, application freezing, a ...@@ -71,7 +54,7 @@ Common fault types include JavaScript application crash, application freezing, a
| Fault | Fault Listening | State Saving| Automatic Restart| Log Query| | Fault | Fault Listening | State Saving| Automatic Restart| Log Query|
| ----------|--------- |--------- |--------- |--------- | | ----------|--------- |--------- |--------- |--------- |
| [JS_CRASH](../reference/apis/js-apis-faultLogger.md#faulttype) | Supported|Supported|Supported|Supported| | [JS_CRASH](../reference/apis/js-apis-faultLogger.md#faulttype) | Supported|Supported|Supported|Supported|
| [APP_FREEZE](../reference/apis/js-apis-faultLogger.md#faulttype) | Not supported|Supported|Supported|Supported| | [APP_FREEZE](../reference/apis/js-apis-faultLogger.md#faulttype) | Not supported|Not supported|Supported|Supported|
| [CPP_CRASH](../reference/apis/js-apis-faultLogger.md#faulttype) | Not supported|Not supported|Not supported|Supported| | [CPP_CRASH](../reference/apis/js-apis-faultLogger.md#faulttype) | Not supported|Not supported|Not supported|Supported|
**State Saving** in the table header means saving of the application state when a fault occurs. To protect user data as much as possible when an AppFreeze occurs, you can adopt either the periodic or automatic way, and the latter will save user data when an ability is switched to the background. **State Saving** in the table header means saving of the application state when a fault occurs. To protect user data as much as possible when an AppFreeze occurs, you can adopt either the periodic or automatic way, and the latter will save user data when an ability is switched to the background.
...@@ -96,31 +79,19 @@ export default class MyAbilityStage extends AbilityStage { ...@@ -96,31 +79,19 @@ export default class MyAbilityStage extends AbilityStage {
appRecovery.SaveModeFlag.SAVE_WITH_FILE); appRecovery.SaveModeFlag.SAVE_WITH_FILE);
} }
} }
```
### Enabling Application Recovery for the Specified Abilities
Generally, the ability configuration list is named **module.json5**.
```json
{
"abilities": [
{
"name": "EntryAbility",
"recoverable": true,
}]
}
``` ```
### Saving and Restoring Data ### Saving and Restoring Data
After enabling **appRecovery**, you can use this function by either actively or passively saving the application state and restoring data in the ability. After enabling **appRecovery**, you can use this function by either actively or passively saving the application state and restoring data in the ability.
The following is an example of **EntryAbility**: The following is an example of **MainAbility**:
#### Importing the Service Package #### Importing the Service Package
```ts ```ts
import errorManager from '@ohos.app.ability.errorManager'; import errorManager from '@ohos.app.ability.errorManager'
import appRecovery from '@ohos.app.ability.appRecovery'; import appRecovery from '@ohos.app.ability.appRecovery'
import AbilityConstant from '@ohos.app.ability.AbilityConstant'; import AbilityConstant from '@ohos.app.ability.AbilityConstant'
``` ```
#### Actively Saving the Application State and Restoring Data #### Actively Saving the Application State and Restoring Data
...@@ -139,7 +110,7 @@ import AbilityConstant from '@ohos.app.ability.AbilityConstant'; ...@@ -139,7 +110,7 @@ import AbilityConstant from '@ohos.app.ability.AbilityConstant';
onWindowStageCreate(windowStage) { onWindowStageCreate(windowStage) {
// Main window is created, set main page for this ability // Main window is created, set main page for this ability
console.log("[Demo] EntryAbility onWindowStageCreate") console.log("[Demo] MainAbility onWindowStageCreate")
globalThis.registerObserver = (() => { globalThis.registerObserver = (() => {
registerId = errorManager.on('error', callback); registerId = errorManager.on('error', callback);
...@@ -151,12 +122,12 @@ import AbilityConstant from '@ohos.app.ability.AbilityConstant'; ...@@ -151,12 +122,12 @@ import AbilityConstant from '@ohos.app.ability.AbilityConstant';
- Save data. - Save data.
After the callback triggers **appRecovery.saveAppState()**, **onSaveState(state, wantParams)** of **EntryAbility** is triggered. After the callback triggers **appRecovery.saveAppState()**, **onSaveState(state, wantParams)** of **MainAbility** is triggered.
```ts ```ts
onSaveState(state, wantParams) { onSaveState(state, wantParams) {
// Ability has called to save app data // Ability has called to save app data
console.log("[Demo] EntryAbility onSaveState") console.log("[Demo] MainAbility onSaveState")
wantParams["myData"] = "my1234567"; wantParams["myData"] = "my1234567";
return AbilityConstant.OnSaveResult.ALL_AGREE; return AbilityConstant.OnSaveResult.ALL_AGREE;
} }
...@@ -164,12 +135,12 @@ After the callback triggers **appRecovery.saveAppState()**, **onSaveState(state, ...@@ -164,12 +135,12 @@ After the callback triggers **appRecovery.saveAppState()**, **onSaveState(state,
- Restore data. - Restore data.
After the callback triggers **appRecovery.restartApp()**, the application is restarted. After the restart, **onCreate(want, launchParam)** of **EntryAbility** is called, and the saved data is stored in **parameters** of **want**. After the callback triggers **appRecovery.restartApp()**, the application is restarted. After the restart, **onCreate(want, launchParam)** of **MainAbility** is called, and the saved data is in **parameters** of **want**.
```ts ```ts
storage: LocalStorage storage: LocalStorage
onCreate(want, launchParam) { onCreate(want, launchParam) {
console.log("[Demo] EntryAbility onCreate") console.log("[Demo] MainAbility onCreate")
globalThis.abilityWant = want; globalThis.abilityWant = want;
if (launchParam.launchReason == AbilityConstant.LaunchReason.APP_RECOVERY) { if (launchParam.launchReason == AbilityConstant.LaunchReason.APP_RECOVERY) {
this.storage = new LocalStorage(); this.storage = new LocalStorage();
...@@ -185,7 +156,7 @@ onCreate(want, launchParam) { ...@@ -185,7 +156,7 @@ onCreate(want, launchParam) {
```ts ```ts
onWindowStageDestroy() { onWindowStageDestroy() {
// Main window is destroyed, release UI related resources // Main window is destroyed, release UI related resources
console.log("[Demo] EntryAbility onWindowStageDestroy") console.log("[Demo] MainAbility onWindowStageDestroy")
globalThis.unRegisterObserver = (() => { globalThis.unRegisterObserver = (() => {
errorManager.off('error', registerId, (err) => { errorManager.off('error', registerId, (err) => {
...@@ -200,10 +171,10 @@ onWindowStageDestroy() { ...@@ -200,10 +171,10 @@ onWindowStageDestroy() {
This is triggered by the recovery framework. You do not need to register an **ErrorObserver** callback. You only need to implement **onSaveState** for application state saving and **onCreate** for data restore. This is triggered by the recovery framework. You do not need to register an **ErrorObserver** callback. You only need to implement **onSaveState** for application state saving and **onCreate** for data restore.
```ts ```ts
export default class EntryAbility extends Ability { export default class MainAbility extends Ability {
storage: LocalStorage storage: LocalStorage
onCreate(want, launchParam) { onCreate(want, launchParam) {
console.log("[Demo] EntryAbility onCreate") console.log("[Demo] MainAbility onCreate")
globalThis.abilityWant = want; globalThis.abilityWant = want;
if (launchParam.launchReason == AbilityConstant.LaunchReason.APP_RECOVERY) { if (launchParam.launchReason == AbilityConstant.LaunchReason.APP_RECOVERY) {
this.storage = new LocalStorage(); this.storage = new LocalStorage();
...@@ -215,26 +186,9 @@ export default class EntryAbility extends Ability { ...@@ -215,26 +186,9 @@ export default class EntryAbility extends Ability {
onSaveState(state, wantParams) { onSaveState(state, wantParams) {
// Ability has called to save app data // Ability has called to save app data
console.log("[Demo] EntryAbility onSaveState") console.log("[Demo] MainAbility onSaveState")
wantParams["myData"] = "my1234567"; wantParams["myData"] = "my1234567";
return AbilityConstant.OnSaveResult.ALL_AGREE; return AbilityConstant.OnSaveResult.ALL_AGREE;
} }
} }
``` ```
#### Restart Flag for the Failed Ability
If the failed ability is restarted again, the [ABILITY_RECOVERY_RESTART](../reference/apis/js-apis-app-ability-wantConstant.md#wantconstantparams) flag will be added as a **parameters** member for the **want** parameter in **onCreate** and its value is **true**.
```ts
import UIAbility from '@ohos.app.ability.UIAbility';
import wantConstant from '@ohos.app.ability.wantConstant';
export default class EntryAbility extends UIAbility {
onCreate(want, launchParam) {
if (want.parameters[wantConstant.Params.ABILITY_RECOVERY_RESTART] != undefined &&
want.parameters[wantConstant.Params.ABILITY_RECOVERY_RESTART] == true) {
console.log("This ability need to recovery");
}
}
}
```
# cppcrash Log Analysis
## Introduction
A process crash refers to a C/C++ runtime crash. The FaultLogger module of OpenHarmony provides capabilities such as process crash detection, log collection, log storage, and log reporting, helping you to locate faults more effectively.
In this document, you'll be guided through how to implement process crash detection, crash log collection, and crash log analysis. Before getting started, make sure you have basic knowledge about C/C++ program stacks.
## Process Crash Detection
Process crash detection is implemented based on the Linux signal mechanism. Currently, C/C++ crash exception signals listed in the following table are supported.
| Signal Value| Signal| Description| Trigger Cause|
| ------ | --------- | --------------- | ------------------------------------------- |
| 4 | SIGILL | Invalid instruction | An invalid, incorrectly formatted, unknown, or privileged instruction is executed.|
| 5 | SIGTRAP | Breakpoint or trap | An exception occurs or a trap instruction is executed.|
| 6 | SIGABRT | Process abort | The process is aborted abnormally. Generally, this problem occurs if the process calls the `abort()` function of the standard function library.|
| 7 | SIGBUS | Illegal memory access | The process accesses an aligned or nonexistent physical address.|
| 8 | SIGFPE | Floating-point exception | The process performs an incorrect arithmetic operation, for example, a 0 divisor, floating point overflow, or integer overflow.|
| 11 | SIGSEGV | Invalid memory access | The process accesses an invalid memory reference.|
| 16 | SIGSTKFLT | Stack error | The processor performs an incorrect stack operation, such as a pop when the stack is empty or a push when the stack is full.|
| 31 | SIGSYS | Incorrect system call | An incorrect or invalid parameter is used in a system call.|
## Crash Log Collection
Process crash log is the fault log managed together with the app freeze and JS application crash logs by the FaultLogger module. You can collect process crash logs in any of the following ways:
### Collecting Logs by Using Shell
- Fault logs in the `/data/log/faultlog/faultlogger/` directory of the device. The log files are named in the format of `cppcrash-process name-process UID-time (seconds level)`. They contain only information such as the device name, system version, and process crash call stack.
![cppcrash-faultlogger-log](figures/20230407112159.png)
- Fault logs in the `/data/log/faultlog/temp/` directory of the device. The log files are named in the format of `cppcrash-process name-process PID-system timestamp (seconds level)`. In addition to basic information, they also contain information such as the stack memory and process maps at the time of process crash.
![cppcrash-temp-log](figures/20230407111853.png)
### Collecting Logs by Using DevEco Studio
DevEco Studio collects process crash logs from `/data/log/faultlog/faultlogger/` to FaultLog, where logs are displayed by process name, fault, and time.
![DevEco Studio cppcrash](figures/20230407112620.png)
### Collecting Logs by Using faultLogger APIs
The FaultLogger module provides APIs to query various fault information. For details, see [@ohos.faultLogger](../reference/apis/js-apis-faultLogger.md).
## Process Crash Log Analysis
### Log Format
The following is an example process crash log archived by DevEco Studio in FaultLog:
```
Generated by HiviewDFX@OpenHarmony
==================================================================
Device info:OpenHarmony 3.2 <- Device information
Build info:OpenHarmony 4.0.5.5 <- Version information
Module name:crasher_c <- Module name
Pid:1205 <- Process ID
Uid:0 <- User ID
Reason:Signal:SIGSEGV(SEGV_ACCERR)@0x0042d33d <- Exception information
Thread name:crasher <- Abnormal thread
#00 pc 0000332c /data/crasher(TriggerSegmentFaultException+15)(8bc37ceb8d6169e919d178fdc7f5449e) <- Call stack
#01 pc 000035c7 /data/crasher(ParseAndDoCrash+277)(8bc37ceb8d6169e919d178fdc7f5449e)
#02 pc 00003689 /data/crasher(main+39)(8bc37ceb8d6169e919d178fdc7f5449e)
#03 pc 000c3b08 /system/lib/ld-musl-arm.so.1(__libc_start_main+116)
#04 pc 000032f8 /data/crasher(_start_c+112)(8bc37ceb8d6169e919d178fdc7f5449e)
#05 pc 00003284 /data/crasher(_start+32)(8bc37ceb8d6169e919d178fdc7f5449e)
...
```
### Locating Faults Through Logs
1. Determine the faulty module and fault type based on fault logs.
Generally, you can identify the faulty module based on the crash process name and identify the crash cause based on the signal. Besides, you can restore the function call chain of the crash stack based on the method name in the stack.
In the example, **SIGSEGV** is thrown by the Linux kernel because of access to an invalid memory address. The problem occurs in the **TriggerSegmentFaultException** function.
In most scenarios, a crash is caused by the top layer of the crash stack, such as null pointer access and proactive program abort.
If the cause cannot be located through the call stack, you need to check for other faults, for example, memory corruption or stack overflow.
2. Use the addr2line tool of Linux to parse the code line number to restore the call stack at the time of process crash.
When using the addr2line tool to parse the code line number of the crash stack, make sure that binary files with debugging information is used. Generally, such files are generated during version build or application build.
Application binary files are located in DevEco Studio's temporary directory for application build, for example, `build/default/intermediates/libs`.
System binary files are stored in the directories listed below. For versions that are directly obtained, the binary files are archived in the image package.
```
\code root directory\out\product\lib.unstripped
\code root directory\out\product\exe.unstripped
```
You can run `apt-get install addr2line` to install the addr2line tool on Linux.
On On DevEco Studio, you can also use the llvm-addr2line tool archived in the SDK to parse code line numbers. The usage method is the same.
The following example shows how to use the addr2line tool to parse the code line number based on the offset address:
```
root:~/OpenHarmony/out/rk3568/exe.unstripped/hiviewdfx/faultloggerd$ addr2line -e crasher 0000332c
base/hiviewdfx/faultloggerd/tools/crasher/dfx_crasher.c:57
```
In this example, the crash is caused by assignment of a value to an unwritable area. It is in code line 57 in the **dfx_crasher.c** file. You can modify it to avoid the crash.
If the obtained code line number is seemingly incorrect, you can fine-tune the address (for example, subtract the address by 1) or disable some compilation optimization items. It is known that the obtained code line number may be incorrect when Link Time Optimization (LTO) is enabled.
...@@ -23,8 +23,7 @@ When an asynchronous callback is used, the return value can be processed directl ...@@ -23,8 +23,7 @@ When an asynchronous callback is used, the return value can be processed directl
| API | Description | | API | Description |
| ------------------------------ | ------------------------------------------------------------ | | ------------------------------ | ------------------------------------------------------------ |
| onUnhandledException(errMsg: string): void | Called when an uncaught exception is reported after the application is registered.| | onUnhandledException(errMsg: string): void | Called when an application generates an uncaught exception after being registered.|
| onException?(errObject: Error): void | Called when an application exception is reported to the JavaScript layer after the application is registered.|
### Result Codes for Unregistering an Observer ### Result Codes for Unregistering an Observer
...@@ -44,13 +43,6 @@ let registerId = -1; ...@@ -44,13 +43,6 @@ let registerId = -1;
let callback = { let callback = {
onUnhandledException: function (errMsg) { onUnhandledException: function (errMsg) {
console.log(errMsg); console.log(errMsg);
},
onException: function (errorObj) {
console.log('onException, name: ', errorObj.name);
console.log('onException, message: ', errorObj.message);
if (typeof(errorObj.stack) === 'string') {
console.log('onException, stack: ', errorObj.stack);
}
} }
} }
......
...@@ -49,11 +49,11 @@ The following example illustrates how to log and subscribe to button click event ...@@ -49,11 +49,11 @@ The following example illustrates how to log and subscribe to button click event
```js ```js
import hilog from '@ohos.hilog'; import hilog from '@ohos.hilog';
import UIAbility from '@ohos.app.ability.UIAbility'; import Ability from '@ohos.application.Ability'
import Window from '@ohos.window' import Window from '@ohos.window'
import hiAppEvent from '@ohos.hiviewdfx.hiAppEvent' import hiAppEvent from '@ohos.hiviewdfx.hiAppEvent'
export default class EntryAbility extends UIAbility { export default class EntryAbility extends Ability {
onCreate(want, launchParam) { onCreate(want, launchParam) {
hilog.isLoggable(0x0000, 'testTag', hilog.LogLevel.INFO); hilog.isLoggable(0x0000, 'testTag', hilog.LogLevel.INFO);
hilog.info(0x0000, 'testTag', '%{public}s', 'Ability onCreate'); hilog.info(0x0000, 'testTag', '%{public}s', 'Ability onCreate');
......
# HiLog Development # HiLog Development (Native)
## Overview ## Introduction
HiLog is the log system of OpenHarmony that provides logging for the system framework, services, and applications to record information on user operations and system running status. HiLog is the log system of OpenHarmony that provides logging for the system framework, services, and applications to record information on user operations and system running status.
> **NOTE** > **NOTE**
> >
> This development guide is applicable only when you use Native APIs for application development. For details about the APIs, see [HiLog Native API Reference](https://gitee.com/openharmony-sig/interface_native_header/blob/master/en/native_sdk/dfx/log.h). > This development guide is applicable only when you use Native APIs for application development. For details about the APIs, see [HiLog Native API Reference](../reference/native-apis/_hi_log.md).
## Available APIs ## Available APIs
| API/Macro| Description| | API/Macro| Description|
| -------- | -------- | | -------- | -------- |
| int OH_LOG_Print(LogType type, LogLevel level, unsigned int domain, const char *tag, const char *fmt, ...) | Outputs logs based on the specified log type, log level, service domain, log tag, and variable parameters determined by the format specifier and privacy identifier in the printf format.<br>Input parameters: See [Parameter Description](#parameter-description).<br>Output parameters: None<br>Return value: total number of bytes if log printing is successful; **-1** otherwise.| | int OH_LOG_Print(LogType type, LogLevel level, unsigned int domain, const char *tag, const char *fmt, ...) | Outputs logs based on the specified log type, log level, service domain, log tag, and variable parameters determined by the format specifier and privacy identifier in the printf format.<br>Input arguments: See [Parameter Description](#parameter-description).<br>Output arguments: None<br>Return value: total number of bytes if log printing is successful; **-1** otherwise.|
| #define OH_LOG_DEBUG(type, ...) ((void)OH_LOG_Print((type), LOG_DEBUG, LOG_DOMAIN, LOG_TAG, \_*VA*ARGS__))| Outputs DEBUG logs. This is a function-like macro.| | #define OH_LOG_DEBUG(type, ...) ((void)OH_LOG_Print((type), LOG_DEBUG, LOG_DOMAIN, LOG_TAG, \_*VA*ARGS__))| Outputs DEBUG logs. This is a function-like macro.|
| #define OH_LOG_INFO(type, ...) ((void)OH_LOG_Print((type), LOG_INFO, LOG_DOMAIN, LOG_TAG, \_*VA*ARGS__)) | Outputs INFO logs. This is a function-like macro.| | #define OH_LOG_INFO(type, ...) ((void)OH_LOG_Print((type), LOG_INFO, LOG_DOMAIN, LOG_TAG, \_*VA*ARGS__)) | Outputs INFO logs. This is a function-like macro.|
| #define OH_LOG_WARN(type, ...) ((void)OH_LOG_Print((type), LOG_WARN, LOG_DOMAIN, LOG_TAG, \_*VA*ARGS__)) | Outputs WARN logs. This is a function-like macro.| | #define OH_LOG_WARN(type, ...) ((void)OH_LOG_Print((type), LOG_WARN, LOG_DOMAIN, LOG_TAG, \_*VA*ARGS__)) | Outputs WARN logs. This is a function-like macro.|
| #define OH_LOG_ERROR(type, ...) ((void)OH_LOG_Print((type), LOG_ERROR, LOG_DOMAIN, LOG_TAG, \_*VA*ARGS__)) | Outputs ERROR logs. This is a function-like macro.| | #define OH_LOG_ERROR(type, ...) ((void)OH_LOG_Print((type), LOG_ERROR, LOG_DOMAIN, LOG_TAG, \_*VA*ARGS__)) | Outputs ERROR logs. This is a function-like macro.|
| #define OH_LOG_FATAL(type, ...) ((void)OH_LOG_Print((type), LOG_FATAL, LOG_DOMAIN, LOG_TAG, \_*VA*ARGS__)) | Outputs FATAL logs. This is a function-like macro.| | #define OH_LOG_FATAL(type, ...) ((void)OH_LOG_Print((type), LOG_FATAL, LOG_DOMAIN, LOG_TAG, \_*VA*ARGS__)) | Outputs FATAL logs. This is a function-like macro.|
| bool OH_LOG_IsLoggable(unsigned int domain, const char *tag, LogLevel level) | Checks whether logs of the specified service domain, tag, and level can be printed.<br>Input parameters: See [Parameter Description](#parameter-description).<br>Output arguments: none<br>Return value: **true** if the specified logs can be printed; **false** otherwise.| | bool OH_LOG_IsLoggable(unsigned int domain, const char *tag, LogLevel level) | Checks whether logs of the specified service domain, tag, and level can be printed.<br>Input arguments: See [Parameter Description](#parameter-description).<br>Output arguments: none<br>Return value: **true** if the specified logs can be printed; **false** otherwise.|
## Parameter Description ## Parameter Description
| Name| Type | Mandatory| Description | | Name| Type | Mandatory| Description |
| ------ | ------ | ---- | ------------------------------------------------------------ | | ------ | ------ | ---- | ------------------------------------------------------------ |
| type | enum | Yes | Enum of log printing types. The default value is **LOG_APP** for application logs.| | type | enum | Yes | Log printing type. The default value is **LOG_APP** for application logs.|
| level | enum | Yes | Log printing level. For details, see [Log Level](#loglevel).| | level | enum | Yes | Log printing level. For details, see [Log Level](#loglevel).|
| domain | number | Yes | Service domain of logs. The value ranges from **0x0** to **0xFFFF**.<br>You can define the value as required. | | domain | number | Yes | Service domain of logs. The value ranges from **0x0** to **0xFFFF**.<br>You can define the value as required. |
| tag | string | Yes | Log tag in the string format. You are advised to use this parameter to identify a particular service behavior or the class holding the ongoing method.| | tag | string | Yes | Log tag in the string format. You are advised to use this parameter to identify a particular service behavior or the class holding the ongoing method.|
...@@ -43,7 +43,7 @@ Log level. ...@@ -43,7 +43,7 @@ Log level.
| ERROR | 6 | Log level used to record program or functional errors that affect the normal running or use of the functionality and can be fixed at a high cost, for example, by resetting data.| | ERROR | 6 | Log level used to record program or functional errors that affect the normal running or use of the functionality and can be fixed at a high cost, for example, by resetting data.|
| FATAL | 7 | Log level used to record program or functionality crashes that cannot be rectified. | FATAL | 7 | Log level used to record program or functionality crashes that cannot be rectified.
## Development Examples ## Development Example
1. Add the link of **libhilog_ndk.z.so** to **CMakeLists.txt**: 1. Add the link of **libhilog_ndk.z.so** to **CMakeLists.txt**:
``` ```
......
...@@ -2,7 +2,9 @@ ...@@ -2,7 +2,9 @@
## Introduction ## Introduction
hiTraceChain is a lightweight implementation of the cloud-based distributed call chain tracing. It allows applications to trace cross-thread, cross-process, and cross-device service calls. The hiTraceChain module generates a unique **chainId** for a service process and passes it to various information (including application events, system time, and logs) specific to the service process. During debugging and fault locating, you can use the unique **chainId** to quickly correlate various information related to the service process. The hiTraceChain module provides APIs to implement call chain tracing throughout a service process. This can help you quickly obtain the run log for the call chain of a specified service process and locate faults in inter-device, inter-process, or inter-thread communications. The hiTraceChain module provides APIs to implement call chain tracing throughout a service process. This can help you quickly obtain the run log for the call chain of a specified service process and locate faults in inter-device, inter-process, or inter-thread communications.
hiTraceChain is a lightweight implementation of the cloud-based distributed call chain tracing. It allows applications to trace cross-thread, cross-process, and cross-device service calls. The hiTraceChain module generates a unique **chainId** for a service process and passes it to various information (including application events, system time, and logs) specific to the service process. During debugging and fault locating, you can use the unique **chainId** to quickly correlate various information related to the service process.
## Basic Concepts ## Basic Concepts
...@@ -16,106 +18,47 @@ The APIs for distributed call chain tracing are provided by the **hiTraceChain** ...@@ -16,106 +18,47 @@ The APIs for distributed call chain tracing are provided by the **hiTraceChain**
**APIs for distributed call chain tracing** **APIs for distributed call chain tracing**
| API | Return Value | Description | | API| Return Value| Description|
| ------------------------------------------------------------------------------------------------------------------- | -------------- | ------------ | | ------------------------------------------------------------------------------------------------------------------- | -------------- | ------------ |
| hiTraceChain.begin(name: string, flags: number = HiTraceFlag.DEFAULT) | HiTraceId | Starts call chain tracing. | | hiTraceChain.begin(name: string, flags: number = HiTraceFlag.DEFAULT) | HiTraceId | Starts call chain tracing.|
| hiTraceChain.end(id: HiTraceId) | void | Stops call chain tracing. | | hiTraceChain.tracepoint(mode: HiTraceCommunicationMode, type: HiTraceTracepointType, id: HiTraceId, msg?: string) | void | Creates a trace point.|
| hiTraceChain.end(id: HiTraceId) | void | Stops call chain tracing.|
## How to Develop ## How to Develop
The following example illustrates how to simulate one-time [system event logging](../reference/apis/js-apis-hisysevent.md) to implement cross-thread distributed call chain tracing in a single HAP service. In this example, distributed call chain tracing begins when the application startup execution page is loaded and stops when the service usage is completed.
1. Create an eTS application project. In the displayed **Project** window, choose **entry** > **src** > **main** > **ets** > **pages** > **index.ets**, and double-click **index.ets**. Then, add a button to trigger system event logging. 1. Create a JS application project. In the displayed **Project** window, choose **entry** > **src** > **main** > **js** > **default** > **pages** > **index**, and double-click **index.js**. Add the code to implement call chain tracing upon page loading. The sample code is as follows:
```ts
import hiTraceChain from '@ohos.hiTraceChain';
import hiSysEvent from '@ohos.hiSysEvent';
@Entry
@Component
struct Index {
@State message: string = 'Start writing system event';
build() {
Row() {
Column() {
Button(this.message)
.fontSize(20)
.margin(5)
.width(350)
.height(60)
.fontWeight(FontWeight.Bold)
.onClick(() => {
try {
// Enable distributed call chain tracing before the service starts.
let traceId = hiTraceChain.begin("Write a new system event", hiTraceChain.HiTraceFlag.INCLUDE_ASYNC);
// Implement one-time system event logging when the service starts.
hiSysEvent.write({
domain: "RELIABILITY",
name: "STACK",
eventType: hiSysEvent.EventType.FAULT,
params: {
PID: 1,
UID: 1,
PACKAGE_NAME: "com.demo.hitracechain",
PROCESS_NAME: "hitracechaindemo",
MSG: "no msg."
}
}).then((val) => {
console.info(`write result is ${val}`);
// Disable distributed call chain tracing when the service ends.
hiTraceChain.end(traceId);
}).catch((err) => {
console.error(`error message is ${err.message}`);
});
} catch (err) {
console.error(`error message is ${err.message}`);
}
})
}
.width('100%')
}
.height('100%')
}
}
```
2. Touch the run button on the IDE to run the project. Then, touch the **Start writing system event** button on the application UI to trigger system event logging.
3. View the information printed in the **Log** window. You can use **.*: \[([0-9a-zA-Z]{15}),.*].*** to access distributed call chain tracing information specific to the HAP service. The process ID of the HAP service is **8801**. Two threads, whose IDs are **8801** and **8819**, are involved in the system event logging. Based on the chain ID **edcfa53017a88e3**, you can then effectively trace the log information of the two threads.
```text
07-05 19:50:47.690 8801-8801/com.demo.hitracechain I C02d03/HiTraceC: [edcfa53017a88e3, 0, 0] HiTraceBegin name:Write a new system event flags:0x01.
07-05 19:50:47.690 8801-8801/com.demo.hitracechain D C02d03/HITRACE_UTIL_NAPI: [edcfa53017a88e3, 0, 0] Native2Js: chainId is edcfa53017a88e3.
07-05 19:50:47.690 8801-8801/com.demo.hitracechain D C02d03/HITRACE_UTIL_NAPI: [edcfa53017a88e3, 0, 0] Native2Js: spanId is 0.
07-05 19:50:47.690 8801-8801/com.demo.hitracechain D C02d03/HITRACE_UTIL_NAPI: [edcfa53017a88e3, 0, 0] Native2Js: parentSpanId is 0.
07-05 19:50:47.690 8801-8801/com.demo.hitracechain D C02d03/HITRACE_UTIL_NAPI: [edcfa53017a88e3, 0, 0] Native2Js: flags is 1.
07-05 19:50:47.690 8801-8801/com.demo.hitracechain D C02d08/NAPI_HISYSEVENT_UTIL: [edcfa53017a88e3, 0, 0] domain is RELIABILITY.
07-05 19:50:47.690 8801-8801/com.demo.hitracechain D C02d08/NAPI_HISYSEVENT_UTIL: [edcfa53017a88e3, 0, 0] name is STACK.
07-05 19:50:47.690 8801-8801/com.demo.hitracechain D C02d08/NAPI_HISYSEVENT_UTIL: [edcfa53017a88e3, 0, 0] eventType is 1.
07-05 19:50:47.690 8801-8801/com.demo.hitracechain E C02d08/NAPI_HISYSEVENT_UTIL: [edcfa53017a88e3, 0, 0] napi value type not match: valueType=3, typeName=6.
07-05 19:50:47.690 8801-8801/com.demo.hitracechain E C02d08/NAPI_HISYSEVENT_UTIL: [edcfa53017a88e3, 0, 0] napi value type not match: valueType=3, typeName=6.
07-05 19:50:47.690 8801-8801/com.demo.hitracechain E C02d08/NAPI_HISYSEVENT_UTIL: [edcfa53017a88e3, 0, 0] napi value type not match: valueType=4, typeName=6.
07-05 19:50:47.690 8801-8801/com.demo.hitracechain E C02d08/NAPI_HISYSEVENT_UTIL: [edcfa53017a88e3, 0, 0] napi value type not match: valueType=4, typeName=6.
07-05 19:50:47.690 8801-8801/com.demo.hitracechain E C02d08/NAPI_HISYSEVENT_UTIL: [edcfa53017a88e3, 0, 0] napi value type not match: valueType=4, typeName=6.
07-05 19:50:47.690 8801-8801/com.demo.hitracechain D C02d08/NAPI_HISYSEVENT_UTIL: [edcfa53017a88e3, 0, 0] create napi value of string type, value is JSHiSysEventWrite.
07-05 19:50:47.690 8801-8801/com.demo.hitracechain I C03900/Ace: [edcfa53017a88e3, 0, 0] [flutter_ace_view.cpp(operator())-(0)] Mark 0 id Touch Event Processed
07-05 19:50:47.690 8801-8801/com.demo.hitracechain D C02800/ClientMsgHandler: [edcfa53017a88e3, 0, 0] in OnDispatchEventProcessed, enter
07-05 19:50:47.690 8801-8801/com.demo.hitracechain D C02800/ANRHandler: [edcfa53017a88e3, 0, 0] in SetLastProcessedEventId, enter
07-05 19:50:47.690 8801-8819/com.demo.hitracechain D C02d08/HISYSEVENT: [edcfa53017a88e3, 0, 0] size=312, sysevent={"domain_":"RELIABILITY","name_":"STACK","type_":1,"time_":47591447690,"tz_":"+0000","pid_":8801,"tid_":8819,"uid_":20010045,"traceid_":"edcfa53017a88e3","spanid_":"0","pspanid_":"0","trace_flag_":1,"UID":1,"PID":1,"MSG":"no msg.","PROCESS_NAME":"hitracechaindemo","PACKAGE_NAME":"com.demo.hitracechain"}
07-05 19:50:47.690 8801-8801/com.demo.hitracechain D C02800/ANRHandler: [edcfa53017a88e3, 0, 0] in SetLastProcessedEventId, Processed event type:0, id:831, actionTime:6694499314, currentTime:6694501330, timeoutTime:4997984
07-05 19:50:47.691 8801-8801/com.demo.hitracechain D C02800/ANRHandler: [edcfa53017a88e3, 0, 0] in SetLastProcessedEventId, leave
07-05 19:50:47.691 8801-8801/com.demo.hitracechain D C02800/ClientMsgHandler: [edcfa53017a88e3, 0, 0] in OnDispatchEventProcessed, leave
07-05 19:50:47.691 8801-8819/com.demo.hitracechain D C02d08/HISYSEVENT: [edcfa53017a88e3, 0, 0] reset send buffer size old=245760, new=524288
07-05 19:50:47.691 8801-8819/com.demo.hitracechain D C02d08/HISYSEVENT: [edcfa53017a88e3, 0, 0] HiSysEvent send data successful
07-05 19:50:47.691 8801-8801/com.demo.hitracechain D C02d08/NAPI_HISYSEVENT_UTIL: [edcfa53017a88e3, 0, 0] create napi value of int32 type, value is 0.
07-05 19:50:47.691 8801-8801/com.demo.hitracechain E A0fefe/JsApp: [edcfa53017a88e3, 399db38, 0] write result is 0
07-05 19:50:47.691 8801-8801/com.demo.hitracechain D C02d03/HITRACE_UTIL_NAPI: [edcfa53017a88e3, 399db38, 0] Js2Native: chainId is edcfa53017a88e3.
07-05 19:50:47.691 8801-8801/com.demo.hitracechain D C02d03/HITRACE_UTIL_NAPI: [edcfa53017a88e3, 399db38, 0] Js2Native: spanId is 0.
07-05 19:50:47.691 8801-8801/com.demo.hitracechain D C02d03/HITRACE_UTIL_NAPI: [edcfa53017a88e3, 399db38, 0] Js2Native: parentSpanId is 0.
07-05 19:50:47.691 8801-8801/com.demo.hitracechain D C02d03/HITRACE_UTIL_NAPI: [edcfa53017a88e3, 399db38, 0] Js2Native: flags is 1.
07-05 19:50:47.691 8801-8801/com.demo.hitracechain I C02d03/HiTraceC: [edcfa53017a88e3, 399db38, 0] HiTraceEnd.
```
## About Cross-Process/Cross-Device Distributed Call Chain Tracing ```
import hiTraceChain from '@ohos.hiTraceChain'
export default {
data: {
title: ""
},
onInit() {
this.title = this.$t('strings.world');
// 1. Enable distributed call chain tracing.
let asyncTraceId = hiTraceChain.begin("business", hiTraceChain.HiTraceFlag.INCLUDE_ASYNC | hiTraceChain.HiTraceFlag.DONOT_CREATE_SPAN);
// 2. Start the service process.
console.log(`business start`);
// 3. Add a trace point.
hiTraceChain.tracepoint(hiTraceChain.HiTraceCommunicationMode.THREAD, hiTraceChain.HiTraceTracepointType.SS, asyncTraceId, "Just an example");
// 4. Keep the service process running.
console.log(`business running`);
// 5. End the service process.
console.log(`business end`);
// 6. Stop call chain tracing.
hiTraceChain.end(asyncTraceId);
}
}
```
Cross-process/cross-device distributed call chain tracing depends on the NAPI implementation of the corresponding service APIs of each OpenHarmony module. For details, see the [HiTraceChain Development](../../device-dev/subsystems/subsys-dfx-hitracechain.md). 2. Click the run button on the application page. Then, you'll obtain the log information for service analysis.
...@@ -17,7 +17,7 @@ hiTraceMeter provides APIs for system performance tracing. You can call the APIs ...@@ -17,7 +17,7 @@ hiTraceMeter provides APIs for system performance tracing. You can call the APIs
## Constraints ## Constraints
- Due to the asynchronous I/O feature of JS, the hiTraceMeter module provides only asynchronous APIs. Due to the asynchronous I/O feature of JS, the hiTraceMeter module provides only asynchronous APIs.
## Available APIs ## Available APIs
......
# FAQs # FAQs
- [Programming Languages](faqs-language.md) - [Ability Development](faqs-ability.md)
- [Ability Framework Development](faqs-ability.md) - [Bundle Management Development](faqs-bundle-management.md)
- [Resource Manager Development](faqs-globalization.md) - [Resource Manager Development](faqs-globalization.md)
- [ArkUI (ArkTS) Development](faqs-ui-ets.md)
- [ArkUI Web Component (ArkTS) Development](faqs-web-arkts.md)
- [ArkUI (JavaScript) Development](faqs-ui-js.md)
- [Common Event and Notification Development](faqs-event-notification.md) - [Common Event and Notification Development](faqs-event-notification.md)
- [Graphics and Image Development](faqs-graphics.md) - [Graphics Development](faqs-graphics.md)
- [Window Management Development](faqs-window-manager.md)
- [Multimedia Development](faqs-multimedia.md)
- [Basic Security Capability Development](faqs-security.md)
- [Ability Access Control Development](faqs-ability-access-control.md)
- [Data Management Development](faqs-distributed-data-management.md)
- [File Management Development](faqs-file-management.md) - [File Management Development](faqs-file-management.md)
- [Media Development](faqs-media.md)
- [Network Management Development](faqs-network-management.md) - [Network Management Development](faqs-network-management.md)
- [DFX Development](faqs-dfx.md) - [DFX Development](faqs-dfx.md)
- [Native API Usage](faqs-native.md) - [Pan-Sensor Development](faqs-sensor.md)
- [Startup Development](faqs-startup.md) - [Startup Development](faqs-startup.md)
- [Usage of Third- and Fourth-Party Libraries](faqs-third-party-library.md) - [Distributed Device Development](faqs-distributed-device-profile.md)
- [IDE Usage](faqs-ide.md) - [Usage of Third- and Fourth-Party Libraries](faqs-third-fourth-party-library.md)
\ No newline at end of file
# Ability Access Control Development
## Can the app listen for the permission change after its permission is modified in Settings?
Applicable to: OpenHarmony 3.1 Beta 5 (API version 9)
Third-party apps cannot listen for the permission change.
# Bundle Management Development
## How do I determine whether an application is a system application?
Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)
**Solution**
Use **bundleManager.getApplicationInfo** (available only for system applications) to obtain application information, and check the value of **systemApp** in the information. The application is a system application if the value is **true**.
**Reference**
[bundleManager](../reference/apis/js-apis-bundleManager.md)
## How do I obtain the version code and version name of an application?
Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)
**Solution**
Use **bundleManager.getBundleInfoForSelf\(\)** to obtain the bundle information, which contains the version code (specified by **BundleInfo.versionCode**) and version name (specified by **BundleInfo.versionName**) .
**Example**
```
import bundleManager from '@ohos.bundle.bundleManager';
import hilog from '@ohos.hilog';
let bundleFlags = bundleManager.BundleFlag.GET_BUNDLE_INFO_DEFAULT;
try {
bundleManager.getBundleInfoForSelf(bundleFlags).then((data) => {
const versionCode = data.versionCode;
const versionName = data.versionName;
hilog.info(0x0000, 'testTag', `successfully. versionCode: ${versionCode}, versionName: ${versionName}`);
}).catch(err => {
hilog.error(0x0000, 'testTag', 'failed. Cause: %{public}s', err.message);
});
} catch (err) {
hilog.error(0x0000, 'testTag', 'failed: %{public}s', err.message);
}
```
**Reference**
[getBundleInfoForSelf](../reference/apis/js-apis-bundleManager.md#bundlemanagergetbundleinfoforself)
## How do I obtain the bundle name of the current application?
Applicable to: OpenHarmony 3.2 Beta5 (API version 9)
**Solution**
Obtain the bundle name from **UIAbilityContext.abilityInfo.bundleName**.
**Example**
```
import common from '@ohos.app.ability.common';
const context = getContext(this) as common.UIAbilityContext
console.log(`bundleName: ${context.abilityInfo.bundleName}`)
```
**Reference**
[UIAbilityContext](../reference/apis/js-apis-inner-application-uiAbilityContext.md#uiabilitycontext) and [AbilityInfo](../reference/apis/js-apis-bundleManager-abilityInfo.md#abilityinfo)
## How do I obtain the application version number, version name, and screen resolution?
Applicable to: OpenHarmony 3.2 Beta5
**Solution**
1. Obtain the bundle information from the **@ohos.bundle.bundleManager** module.
The bundle information contains the application version number and version name.
```
import bundleManager from '@ohos.bundle.bundleManager';
...
bundleManager.getBundleInfoForSelf(bundleManager.BundleFlag.GET_BUNDLE_INFO_WITH_APPLICATION).then((bundleInfo)=>{
let versionName = bundleInfo.versionName; // Application version name.
let versionNo = bundleInfo.versionCode; // Application version number.
}).catch((error)=>{
console.error("get bundleInfo failed,error is "+error)
})
```
2. Obtain **screenDensity** from the **@ohos.app.ability.Configuration** module. **screenDensity** contains the screen resolution information.
```
import common from '@ohos.app.ability.common';
...
let context = getContext(this) as common.UIAbilityContext;
let screenDensity = context.config.screenDensity;
```
## How do I obtain the source file path of the current application?
Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)
**Solution**
- Method 1: Use the application context to obtain the source file path.
```
this.uiAbilityContext.abilityInfo.applicationInfo.codePath
```
- Method 2: Use **@ohos.bundle.bundleManager** to obtain the source file path.
1. Import the **@ohos.bundle.bundleManager** module and use **bundleManager.getBundleInfoForSelf\(\)** to obtain the bundle information.
2. Obtain the source file path from **bundleInfo.appInfo.codePath**.
```
import bundleManager from '@ohos.bundle.bundleManager';
bundleManager.getBundleInfoForSelf(bundleManager.BundleFlag.GET_BUNDLE_INFO_WITH_APPLICATION).then((bundleInfo)=>{
this.sourcePath = bundleInfo.appInfo.codePath;
})
```
## Can I obtain the HAP information of other applications from the current application?
Applicable to: OpenHarmony 3.2 Beta (API version 9)
According to the OpenHarmony security design specifications, the SDK does not provide APIs for third-party applications to obtain bundle information (including but not limited to the application name and version number) of other applications.
# Bundle Management Development
## How do I obtain the version code and version name of an application?
Applicable to: OpenHarmony SDK 3.2.3.5, stage model of API version 9
Use **bundle.getBundleInfo()** to obtain the bundle information, which contains the version code and version name.
Reference: [Bundle](../reference/apis/js-apis-Bundle.md#bundlegetbundleinfo)
## How do I obtain the bundle name of an application?
Applicable to: OpenHarmony SDK 3.2.3.5, stage model of API version 9
Obtain the bundle name through **context.abilityInfo.bundleName**.
Reference: [AbilityInfo](../reference/apis/js-apis-bundle-AbilityInfo.md)
## How do I obtain an application icon?
Applicable to: OpenHarmony SDK 3.2.3.5, stage model of API version 9
Use **bundle.getAbilityIcon** to obtain the application icon. To use this API, you must configure the permission **ohos.permission.GET_BUNDLE_INFO**.
Reference: [Bundle](../reference/apis/js-apis-Bundle.md#bundlegetbundleinfo)
## How do I determine whether an application is a system application?
Applicable to: OpenHarmony SDK 3.2.5.5, stage model of API version 9
Use **bundle.getApplicationInfo** to obtain the application information, and then check the value of **systemApp** in the information. The application is a system application if the value is **true**.
# Data Management Development
## How do I encrypt an RDB store?
Applicable to: OpenHarmony 3.1 Beta 5 (API version 9)
**Solution**
To encrypt an RDB store, set **encrypt** in **StoreConfig** to **true** when creating the RDB store.
**Reference**
[RDB Store](../reference/apis/js-apis-data-relationalStore.md#storeconfig)
## What if I failed to clear a table in an RDB store using TRUNCATE TABLE?
Applicable to: OpenHarmony SDK 3.2.9.2 (API version 9)
**Symptom**
An error is reported when the **TRUNCATE TABLE** statement is used to clear table data.
**Solution**
The RDB store uses SQLite and does not support the **TRUNCATE TABLE** statement. To clear a table in an RDB store, use the **DELETE** statement, for example, **DELETE FROM sqlite\_sequence WHERE name = 'table\_name'**.
## What data types does an RDB store support?
Applicable to: OpenHarmony SDK 3.0 or later, API version 9 stage model
**Solution**
An RDB store supports data of the number, string, and Boolean types. The number type supports data of the Double, Long, Float, Int, or Int64 type, with a maximum precision of 17 decimal digits.
## How do I save pixel map data to a database?
Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)
**Symptom**
Pixel map data fails to be stored.
**Solution**
Convert the pixel map data into an **ArrayBuffer** and save the **ArrayBuffer** to your database.
**Reference**
[readPixelsToBuffer](../reference/apis/js-apis-image.md#readpixelstobuffer7-1)
## How do I obtain RDB store files?
Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)
**Solution**
The RDB store files are stored in **/data/app/el2/100/database/*Bundle_name*/entry/rdb/**. You can use the hdc command to copy the file from the directory and use a SQLite tool to open the file.
Example:
```
hdc file recv /data/app/el2/100/database/<bundleName>/entry/db/<tableName> ./<path>
```
## Do the OpenHarmony databases have a lock mechanism?
Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)
**Solution**
The distributed data service (DDS), RDB store, and preferences provided OpenHarmony have a lock mechanism. You do not need to bother with the lock mechanism during the development.
## What if I failed to use get() to obtain the data saved by @ohos.data.storage put()?
Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)
**Symptom**
After @ohos.data.storage **put()** is called to save data, **get()** is called to obtain the data. However, the data fails to be obtained.
**Solution**
The **put()** method provided by **@ohos.data.storage** saves data in the memory. When the application exits, the data in the memory will be cleared. If you want to persist the data, you need to call **flush()** or **flushSync()** after **put()**. After data is persisted, you can use **get()** to obtain the data after the application is restarted.
## What if a large text file fails to be saved in an RDB store?
Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)
**Symptom**
In API version 8, large text files cannot be saved in RDB stores.
**Solution**
In versions earlier than API version 9, the maximum length of a text file is 1024 bytes. If the text file exceeds 1024 bytes, it cannot be saved.
The limit on the text file size has been removed since API9 version.
# Distributed Device Development
## How do I view the IMEI of an OpenHarmony device?
Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)
**Solution**
Obtain the device IMEI from the **HUKS\_TAG\_ATTESTATION\_ID\_IMEI** parameter of the **HuksTag** API. [Reference](../reference/apis/js-apis-huks.md)
# File Management Development # File Management Development
## Does fileio.rmdir Delete Files Recursively? ## How do I obtain the path of system screenshots?
Applicable to: OpenHarmony SDK 3.2.6.3, stage model of API version 9 Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)
Yes. **fileio.rmdir** deletes files recursively. **Solution**
## How Do I Create a File That Does Not Exist? The screenshots are stored in **/storage/media/100/local/files/Pictures/Screenshots/**.
Applicable to: OpenHarmony SDK 3.2.6.3, stage model of API version 9 ## How do I change the permissions on a directory to read/write on a device?
You can use **fileio.open(filePath, 0o100, 0o666)**. The second parameter **0o100** means to create a file if it does not exist. The third parameter **mode** must also be specified. Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)
## What If "call fail callback fail, code: 202, data: json arguments illegal" Is Displayed? **Symptom**
Applicable to: OpenHarmony SDK 3.2.6.3, stage model of API version 9 When the hdc command is used to send a file to a device, "permission denied" is displayed.
When the **fileio** module is used to copy files, the file path cannot start with "file:///". **Solution**
## How Do I Read Files Outside the App Sandbox? Run the **hdc shell mount -o remount,rw /** command to grant the read/write permissions.
Applicable to: OpenHarmony SDK 3.2.6.5, stage model of API version 9
If the input parameter of the **fileio** API is **path**, only the sandbox directory of the current app obtained from the context can be accessed. To access data in other directories such as the user data, images, and videos, open the file as the data owner and operate with the file descriptor (FD) returned.
For example, to read or write a file in Media Library, perform the following steps:
1. Use **getFileAssets()** to obtain the **fileAsset** object.
2. Use **fileAsset.open()** to obtain the FD.
3. Use the obtained FD as the **fileIo** API parameter to read and write the file.
## What If the File Contains Garbled Characters?
Applicable to: OpenHarmony SDK 3.2.5.5, stage model of API version 9
Read the file content from the buffer, and decode the file content using **util.TextDecoder**.
Example:
```
import util from '@ohos.util'
async function readFile(path) {
let stream = fileio.createStreamSync(path, "r+");
let readOut = await stream.read(new ArrayBuffer(4096));
let textDecoder = new util.TextDecoder("utf-8", { ignoreBOM: true });
let buffer = new Uint8Array(readOut.buffer)
let readString = textDecoder.decode(buffer, { stream: false });
console.log ("[Demo] File content read: "+ readString);
}
```
## What Should I Do If There Is No Return Value or Error Captured After getAlbums Is Called?
Applicable to: OpenHarmony SDK 3.2.5.3, stage model of API version 9
The **ohos.permission.READ_MEDIA** is required for using **getAlbums()**. In addition, this permission needs user authorization. For details, see [OpenHarmony Permission List](../security/permission-list.md).
1. Configure the required permission in the **module.json5** file.
```
"requestPermissions": [
{
"name": "ohos.permission.READ_MEDIA"
}
]
```
2. Add the code for user authorization before the **MainAbility.ts -> onWindowStageCreate** page is loaded.
```
import abilityAccessCtrl from '@ohos.abilityAccessCtrl.d.ts';
private requestPermissions() {
let permissionList: Array<string> = [
"ohos.permission.READ_MEDIA"
];
let atManager = abilityAccessCtrl.createAtManager();
atManager.requestPermissionsFromUser(this.context, permissionList)
.then(data => {
console.info(`request permission data result = ${data.authResults}`)
})
.catch(err => {
console.error(`fail to request permission error:${err}`)
})
}
```
## What Do I Do If the App Crashes When FetchFileResult() Is Called Multiple Times?
Applicable to: OpenHarmony SDK 3.2.5.5, stage model of API version 9
Each time after the **FetchFileResult** object is called, call **FetchFileResult.close()** to release and invalidate the **FetchFileResult** object .
## What If An Error Is Reported by IDE When mediaLibrary.getMediaLibrary() Is Called in the Stage Model?
Applicable to: OpenHarmony SDK 3.2.5.5, stage model of API version 9
In the stage model, use **mediaLibrary.getMediaLibrary(context: Context)** to obtain the media library instance.
## How Do I Sort the Data Returned by mediaLibrary.getFileAssets()?
Applicable to: OpenHarmony SDK 3.2.5.5, stage model of API version 9
Use the **order** attribute in **[MediaFetchOptions](../reference/apis/js-apis-medialibrary.md#mediafetchoptions7)** to sort the data returned.
# Graphics and Image Development # Graphics Development
## Why do the isStatusBarLightIcon and isNavigationBarLightIcon attributes not take effect when window.setSystemBarProperties() is called? ## How do I obtain the DPI of a device?
Applicable to: OpenHarmony SDK 3.2.5.3, stage model of API version 9 Applicable to: OpenHarmony 3.2 Beta5 (API version 9, stage model)
In effect, the **isStatusBarLightIcon** and **isNavigationBarLightIcon** attributes turn the font white when set to **true**. If **statusBarContentColor** is also set in **window.setSystemBarProperties()**, the **isStatusBarLightIcon** attribute does not take effect. Similarly, if **navigationBarContentColor** is set, the **isNavigationBarLightIcon** attribute does not take effect. **Solution**
## How do I set the style of the system bar? Import the **@ohos.display** module and call the **getDefaultDisplaySync\(\)** API.
Applicable to: OpenHarmony SDK 3.2.3.5, stage model of API version 9 **Example**
Import the **\@ohos.window** module, and call **window.setSystemBarProperties()**. ```
import display from '@ohos.display';
let displayClass = null;
try {
displayClass = display.getDefaultDisplaySync();
console.info('Test densityDPI:' + JSON.stringify(displayClass.densityDPI));
} catch (exception) {
console.error('Failed to obtain the default display object. Code: ' + JSON.stringify(exception));
}
```
## How do I hide the status bar to get the immersive effect? ## How do I hide the status bar to get the immersive effect?
Applicable to: OpenHarmony SDK 3.2.6.3, stage model of API version 9 Applicable to: OpenHarmony 3.2 Beta5 (API version 9, stage model)
1. Use the **onWindowStageCreate** to obtain a **windowClass** object. **Solution**
```ts 1. Use **onWindowStageCreate** to obtain a **windowClass** object.
onWindowStageCreate(windowStage) {
// When the main window is created, set the main page for this ability. ```
console.log("[Demo] EntryAbility onWindowStageCreate") onWindowStageCreate(windowStage) {
windowStage.getMainWindow((err, data) => { // When the main window is created, set the main page for this ability.
if (err.code) { console.log("[Demo] MainAbility onWindowStageCreate")
console.error('Failed to obtain the main window.') windowStage.getMainWindow((err, data) => {
return; if (err.code) {
} console.error('Failed to obtain the main window.')
// Obtain a windowClass object. return;
globalThis.windowClass = data; }
}) // Obtain a windowClass object.
} globalThis.windowClass = data;
``` })
}
2. Enable the full-screen mode for the window and hide the status bar. ```
```ts 2. Enable the full-screen mode for the window and hide the status bar.
globalThis.windowClass.setFullScreen(isFullScreen, (err, data) => {
if (err.code) { ```
console.error('Failed to enable the full-screen mode. Cause:' + JSON.stringify(err)); globalThis.windowClass.setFullScreen(isFullScreen, (err, data) => {
return; if (err.code) {
} console.error('Failed to enable the full-screen mode. Cause:' + JSON.stringify(err));
console.info('Succeeded in enabling the full-screen mode. Data: ' + JSON.stringify(data)); return;
}); }
``` console.info('Succeeded in enabling the full-screen mode. Data: ' + JSON.stringify(data));
});
```
## How do I obtain the window width and height? ## How do I obtain the window width and height?
Applicable to: OpenHarmony SDK 3.2.3.5, stage model of API version 9 Applicable to: OpenHarmony SDK 3.2 Beta5 (API version 9, stage model)
Use **window.getProperties()** to obtain the window properties. The **windowRect** field in the properties specifies the window width and height. **Solution**
Example: Import the **@ohos.window** module, obtain a **Window** object, and use **getWindowProperties\(\)** of the object to obtain the window properties. The **windowRect** field in the properties specifies the window width and height.
**Example**
```ts
let promise = windowClass.getProperties();
promise.then((data)=> {
console.info('Succeeded in obtaining the window properties. Data: ' + JSON.stringify(data.windowRect));
}).catch((err)=>{
console.error('Failed to obtain the window properties. Cause: ' + JSON.stringify(err));
});
``` ```
import window from '@ohos.window';
## How do I set the color of the system bar? let windowClass = null;
try {
Applicable to: OpenHarmony SDK 3.2.5.5, stage model of API version 9 let promise = window.getLastWindow(this.context);
promise.then((data)=> {
Refer to the following code: // Obtain a Window object.
windowClass = data;
try {
```ts // Obtain the window properties.
window.getTopWindow(globalThis.mainContext).then(win => { let properties = windowClass.getWindowProperties();
var systemBarProperties = { let rect = properties.windowRect;
statusBarColor: '#19B6FF', // Set the background color of the status bar. // rect.width: window width; rect.height: window height.
navigationBarColor: '#19B6FF', // Set the background color of the navigation bar. } catch (exception) {
isStatusBarLightIcon: false, // Set the icon on the status bar not to be highlighted. console.error('Failed to obtain the window properties. Cause: ' + JSON.stringify(exception));
isNavigationBarLightIcon: true, // Set the icon on the navigation bar to be highlighted. }
statusBarContentColor: '#0D0500', // Set the text color of the status bar. console.info('Succeeded in obtaining the top window. Data: ' + JSON.stringify(data));
navigationBarContentColor: '#FFA500' // Set the text color of the navigation bar. }).catch((err)=>{
}; console.error('Failed to obtain the top window. Cause: ' + JSON.stringify(err));
win.setSystemBarProperties(systemBarProperties).catch(err => { });} catch (exception) {
INDEX_LOGGER.info(`set System Bar Properties failed:${err}`) console.error('Failed to obtain the top window. Cause: ' + JSON.stringify(exception));
}) }
})
.catch(err => {
INDEX_LOGGER.info(`get top window failed:${err}`)
})
``` ```
# IDE Usage
## What should I do if the error message "npm ERR! code SELF_SIGNED_CERT_IN_CHAIN" is displayed?
Applicable to: OpenHarmony SDK 3.2.5.3, stage model of API version 9
1. Run **npm config set strict-ssl=false** on the DevEco Studio terminal.
2. Run **npm install** on the DevEco Studio terminal.
## After manual updating of a DevEco Studio SDK, the error message "Cannot find module 'xxx\ets\x.x.x.x\build-tools\ArkTS-loader\node_modules\webpack\bin\webpack.js'" is displayed during HAP building. What should I do?
Applicable to: OpenHarmony SDK 3.2.5.3, stage model of API version 9
1. Run **npm install** in the **ets\x.x.x.x\build-tools\ets-loader** directory of the SDK.
2. Run **npm install** in the **js\x.x.x.x\build-tools\ace-loader** directory of the SDK. Perform HAP building again.
## How do I pack a HAP file through the command line?
Applicable to: OpenHarmony SDK 3.2.5.5, stage model of API version 9
Method 1: Run **hvigor assembleHap**.
Method 2: In **scripts** of the project **package.json** file, define the build task script and run **npm buildOhosHaps**. The **buildOhosHaps** field can be customized.
```
"scripts": {
"buildOhosHaps": "hvigor assembleHap"
},
```
## How do I select API version 9 when creating a project in DevEco Studio?
Applicable to: DevEco Studio 3.0 Beta4 3.0.0.993(B06)
When creating a project in DevEco Studio, make sure you are on the **OpenHarmony** tab page.
## What should I do if no callback is received and no error code is returned for downloads?
Applicable to: all versions
1. Re-install hdc_std and set up the device connection again.
2. Run **hdc_std shell hilog -Q pidoff** to disable log log flow control.
## What should I do if the "error: unknow option. usage: aa start \<options>" message is displayed after I click Run in DevEco Studio?
Applicable to: OpenHarmony SDK 3.2.5.6, stage model of API version 9
This issue occurs when the parameter in the **aa** command is invalid and therefore the target application fails to be opened.
To fix this issue, use either of the following methods:
1. Make sure the SDK version and the OS version are the same.
2. Touch the application icon on the device to manually open the application.
## What should I do if "The hdc_std version of the SDK does not match the hdcd version of the device." message is displayed when I run an application in DevEco Studio?
Applicable to: OpenHarmony SDK 3.2.5.6, stage model of API version 9
This issue occurs when the hdc and hdcd versions do not match. Update Dev Eco Studio to 3.0.1.993 or later.
After the update, Dev Eco Studio will still indicate the version mismatch, but will not block the running.
## How do I add a custom .d.ts file to the OpenHarmony SDK?
Applicable to: OpenHarmony SDK 3.1.7.7, FA model of API version 8
Name the .d.ts file **@ohos.xxxx.d.ts**, save it to the SDK path, and restart Dev Eco Studio.
A code notification is displayed when the file is imported.
## How do I switch to the full SDK?
Applicable to: OpenHarmony SDK 3.2.7.5
Follow the instructions in [Guide to Switching to Full SDK](../quick-start/full-sdk-switch-guide.md).
# Programming Languages
## What are the restrictions on using generator functions in TypeScript?
Applicable to: OpenHarmony SDK 3.2.5.3, stage model of API version 9
Below are the restrictions on using generator functions in TypeScript:
- Expressions can be used only in character strings (in the ${expression} format), **if** conditions, **ForEach** parameters, and component parameters.
- No expressions should cause any application state variables (including **@State**, **@Link**, and **@Prop**) to change. Otherwise, undefined and potentially unstable framework behavior may occur.
- The generator function cannot contain local variables.
None of the above restrictions apply to anonymous function implementations of event handlers (such as **onClick**).
Negative example:
```
build() {
let a: number = 1 // invalid: variable declaration not allowed
Column() {
Text('Hello ${this.myName.toUpperCase()}') // ok.
ForEach(this.arr.reverse(), ..., ...) // invalid: Array.reverse modifies the @State array variable in place
}
buildSpecial() // invalid: no function calls
Text(this.calcTextValue()) // this function call is ok.
}
```
## How do I dynamically replace the %s placeholder in a resource file?
Applicable to: OpenHarmony SDK 3.2.5.3, stage model of API version 9
In an application, you can replace the %s placeholder by using the second parameter in **$r('app.string.xx')**, which is used to reference application resources.
Example:
```
build() {
//do something
// The second parameter indicates the referenced string resource, which can be used to replace the %s placeholder.
Text($r('app.string.entry_desc','aaa'))
.fontSize(100)
.fontColor(Color.Black)
//do something
}
```
## How do I read an XML file in Resource and convert data in it to the string type?
Applicable to: OpenHarmony SDK 3.2.2.5, stage model of API version 9
1. Obtain Uint8Array data by calling the **RawFile** API of **resourceManager**.
2. Convert the Uint8Array data to strings by calling the **String.fromCharCode** API.
Reference: [Resource Manager](../reference/apis/js-apis-resource-manager.md)
Example:
```
resourceManager.getRawFile(path, (error, value) => {
if (error != null) {
console.log("error is " + error);
} else {
let rawFile = value;
let xml = String.fromCharCode.apply(null, rawFile)
}
});
```
## How do I convert a Resource object to the string type?
Applicable to: OpenHarmony SDK 3.2.3.5, stage model of API version 9
Use the **resourceManager.getString()** API of the **@ohos.resourceManager** module.
Reference: [Resource Manager](../reference/apis/js-apis-resource-manager.md#getstring)
## What should I do if the global static variables of a class do not work?
Applicable to: OpenHarmony SDK 3.2.3.5, stage model of API version 9
Objects imported to abilities and pages are packaged into two different closures, that is, two global objects. In this case, a static variable referenced by the abilities is not the same object as that referenced by the pages. Therefore, global variables cannot be defined by defining static variables in the class. You are advised to use AppStorage to manage global variables.
## How do I obtain resources in the stage model?
Applicable to: OpenHarmony SDK 3.2.3.5, stage model of API version 9
The stage model allows an application to obtain a **ResourceManager** object based on **context** and call its resource management APIs without first importing the required bundle. This method, however, is not applicable to the FA model.
Example:
```
const context = getContext(this) as any
context
.resourceManager
.getString($r('app.string.entry_desc').id)
.then(value => {
this.message = value.toString()
})
```
## How do I obtain data through an API before page loading?
Applicable to: OpenHarmony SDK 3.2.5.5, stage model of API version 9
In the **aboutToAppear** function, use an asynchronous API to obtain page data and **@State** to decorate related variables. After the data is obtained, the page is automatically refreshed based on the variables.
```
@Entry
@Component
struct Test6Page {
// After the data is obtained, the page is automatically refreshed.
@State message: string = 'loading.....'
aboutToAppear(){
// Simulate an asynchronous API to obtain data.
setTimeout(()=>{
this.message = 'new msg'
},3000)
}
build() {
Row() {
Column() {
Text(this.message)
.fontSize(50)
.fontWeight(FontWeight.Bold)
}
.width('100%')
}
.height('100%')
}
}
```
## Do the worker thread and the main thread run in the same global context?
Applicable to: OpenHarmony SDK 3.2.5.5, stage model of API version 9
No. The worker thread and the main thread are not in the same global context. They interact with each other in data communication mode.
## Which API is used for URL encoding in OpenHarmony?
Applicable to: OpenHarmony SDK 3.2.5.5, stage model of API version 9
The global function **encodeURI** is used for URI encoding, and **decodeURI** is used for URI decoding. For example, a space character is encoded as %20.
## Does OpenHarmony provide any API for parsing XML files?
Applicable to: OpenHarmony SDK 3.2.5.5, stage model of API version 9
Yes. The **convert** API of the **convertxml** module can be used to convert XML text into JavaScript objects.
Reference: [@ohos.convertxml](../reference/apis/js-apis-convertxml.md)
## How do I configure application icons to be used across devices?
Applicable to: OpenHarmony SDK 3.0, stage model of API version 9
Use resource qualifiers to configure application icons to be used across devices.
## Can placeholders be configured in the string.json file of the stage model?
Applicable to: OpenHarmony SDK 3.2.6.3, stage model of API version 9
The **string.json** file does not support placeholders. As an alternative, you can define variables on the target page and combine these variables and **Resource** objects.
## Is there any difference between the OpenHarmony API systemTime.getCurrentTime() and the JS API new Date().getTime() API?
Applicable to: OpenHarmony SDK 3.2.6.3, stage model of API version 9
Similar to **new Date().getTime()**, **systemTime.getCurrentTime(false)** returns the number of milliseconds that have elapsed since the Unix epoch. **systemTime.getCurrentTime(true)** returns the number of nanoseconds that have elapsed since the Unix epoch. The system time is used in both APIs.
## How do I define @BuilderParam decorated attributes based on the value assigned to them?
Applicable to: OpenHarmony SDK 3.2.6.5, stage model of API version 9
If no parameter is passed when assigning a value to the **@BuilderParam** decorated attribute (for example, **content: this.specificParam**), define the type of the attribute as a function without a return value (for example, **@BuilderParam content: () =&gt; voi**). If any parameter is passed when assigning a value to the **@BuilderParam** decorated attribute (for example, **callContent: this.specificParam1("111")**), define the type of the attribute as **any** (for example, **@BuilderParam callContent: any**).
## How does ArkTS convert a string into a byte array?
Applicable to: all versions
Refer to the following code:
```
function stringToByte(str) {
var bytes = new Array();
var len,c;
len = str.length;
for(var i = 0;i<len;i++) {
c = str.charCodeAt(i);
if( c >= 0x010000 && c<= 0x10FFFF) {
bytes.push(((c>>18) & 0x07) | 0xf0);
bytes.push(((c>>12) & 0x3F) | 0x80);
bytes.push(((c>>6) & 0x3f) | 0x80);
bytes.push((c & 0x3F) | 0x80);
} else if(c >= 0x000800 && c<= 0x00FFF){
bytes.push(((c>>12) & 0x07) | 0xf0);
bytes.push(((c>>6) & 0x3F) | 0x80);
bytes.push((c & 0x3F) | 0x80);
} else if(c >= 0x000800 && c<= 0x0007FF) {
bytes.push(((c>>6) & 0x3F) | 0x80);
bytes.push((c & 0x3F) | 0x80);
} else {
bytes.push(c & 0xFF)
}
}
return bytes;
}
```
## What do I do if the "Too many wokers, the number of worker exceeds the maximum" message is displayed during worker creation?
Applicable to: OpenHarmony SDK 3.2.6.5
An application allows for a maximum of seven workers. Therefore, use the **termiate** API to release workers when they are not needed.
Reference: [@ohos.worker](../reference/apis/js-apis-worker.md#terminate)
## What is the recommended multithreading solution on OpenHarmony?
Applicable to: OpenHarmony SDK 3.2.6.5, stage model of API version 9
OpenHarmony recommends that worker threads be used for multithreading.
Reference: [@ohos.worker](../reference/apis/js-apis-worker.md)
## What is the difference between a @Builder decorated method and other methods?
Applicable to: OpenHarmony SDK 3.2.6.5, stage model of API version 9
If the **@Builder** decorated method uses a custom component, this component is re-created each time the method is called.
## Why is the callback registered through @Watch not triggered when the object attributes of an array change?
Applicable to: OpenHarmony SDK 3.2.6.5, stage model of API version 9
As with **@State**, the callback registered through **@Watch** can be used to listen for only one layer of data changes. If the object attributes of the array changes at the inner layer, the callback will not be triggered.
## How do I listen for in-depth changes of @State decorated variables?
Applicable to: OpenHarmony SDK 3.2.5.5, stage model of API version 9
To listen for in-depth changes of **@State** decorated variables, you can use **@Observed** and **@ObjectLink** decorators.
## How do I implement character string encoding and decoding?
Applicable to: OpenHarmony SDK 3.2.5.5, stage model of API version 9
You can use **TextEncoder** and **TextDecoder** provided by the **util** module.
Reference: [TextEncoder](../reference/apis/js-apis-util.md#textencoder) and [TextDecoder](../reference/apis/js-apis-util.md#textdecoder)
## How do i import and export namespaces?
Applicable to: OpenHarmony SDK 3.2.5.5, stage model of API version 9
- Exporting namespaces
```
namespace Util{
export function getTime(){
return Date.now()
}
}
export default Util
```
- Importing namespaces
```
import Util from './util'
Util.getTime()
```
## Can relational database operations be performed in the worker thread?
Applicable to: OpenHarmony SDK 3.2.5.5, stage model of API version 9
No. Relational database operations cannot be performed in the worker thread.
<!--no_check-->
\ No newline at end of file
# Media Development
## How do I set a front camera?
Applicable to: OpenHarmony SDK 3.2.3.5, stage model of API version 9
1. Set the camera position to **camera.CameraPosition.CAMERA_POSITION_FRONT**.
2. Create a **CameraInput** instance based on the camera position and type.
Reference: [Camera Management](../reference/apis/js-apis-camera.md)
Example:
```
// The rear camera is set by default. You can use **isFrontCamera** to switch to the rear camera.
let cameraId
let cameraInput
for(let cameraIndex = 0; cameraIndex < this.cameraArray.length; cameraIndex++) {
let faceType = this.cameraArray[cameraIndex].cameraPosition
switch(faceType) {
case camera.CameraPosition.CAMERA_POSITION_FRONT: // Front camera
if(this.isFrontCamera){
cameraId = this.cameraArray[cameraIndex].cameraId
}
break
case camera.CameraPosition.CAMERA_POSITION_BACK: // Rear camera
if(!this.isFrontCamera){
cameraId = this.cameraArray[cameraIndex].cameraId
}
break
case camera.CameraPosition.CAMERA_POSITION_UNSPECIFIED:
default:
break
}
}
cameraInput = await this.cameraManager.createCameraInput(cameraId)
```
## How do I crop an image?
Applicable to: OpenHarmony SDK 3.2.5.6, stage model of API version 9
1. Create an **ImageSource** instance based on the input URI.
```
let path = this.context.getApplicationContext().fileDirs + "test.jpg";
const imageSourceApi = image.createImageSource(path);
```
2. Set decoding parameters and decode the image to obtain a **PixelMap** object. Image processing is supported during decoding.
- Set **desiredSize** to specify the target size after scaling. If the values are all set to **0**, scaling will not be performed.
- Set **desiredRegion** to specify the target rectangular area after cropping. If the values are all set to **0**, cropping will not be performed.
- Set **rotateDegrees** to specify the rotation angle. The image will be rotated clockwise at the center.
```
const decodingOptions = {
desiredSize: {
height:0,
width:0
},
// Crop a rectangular area.
desiredRegion: {
size: {
height:100,
width:100
},
x:0,
y:0
},
// Rotate the image by 90 degrees.
rotate:90
}
imageSourceApi.createPixelMap(decodingOptions).then(pixelMap => {
this.handlePixelMap(pixelMap)
})
```
3. Process the obtained **PixelMap** object. For example, render and display the image.
## How do I apply for the media read/write permission on a device?
Applicable to: OpenHarmony SDK 3.2.5.5, stage model of API version 9
1. Configure the permissions **ohos.permission.READ_MEDIA** and **ohos.permission.WRITE_MEDIA** in the **module.json5** file.
Example:
```
{
"module" : {
"requestPermissions":[
{
"name" : "ohos.permission.READ_MEDIA",
"reason": "$string:reason"
},
{
"name" : "ohos.permission.WRITE_MEDIA",
"reason": "$string:reason"
}
]
}
}
```
2. Call **requestPermissionsFromUser** to request the permissions from end users in the form of a dialog box. This operation is required because the grant mode of both permissions is **user_grant**.
```
import abilityAccessCtrl from '@ohos.abilityAccessCtrl.d.ts';
let permissions: Array<string> = ['ohos.permission.READ_MEDIA','ohos.permission.WRITE_MEDIA']
let atManager = abilityAccessCtrl.createAtManager();
// context is the ability-level context of the initiator UIAbility.
atManager.requestPermissionsFromUser(context, permissions).then((data) => {
console.log("Succeed to request permission from user with data: " + JSON.stringify(data))
}).catch((error) => {
console.log("Failed to request permission from user with error: " + JSON.stringify(error))
})
```
## Why can't I play MP4 videos?
Applicable to: OpenHarmony SDK 3.2.7.5, stage model of API version 9
Currently, the system does not support the playback of MP4 videos in H.265 format.
## Why can't I play a new video or even encounters a crash after creating more than 10 videos?
Applicable to: OpenHarmony SDK 3.2.7.5, stage model of API version 9
A maximum of 13 media player instances can be created.
# Multimedia Development
## How do I obtain the frame data of a camera when using the XComponent to display the preview output stream of the camera?
Applicable to: OpenHarmony 3.2 (API version 9, stage model)
**Symptom**
Currently, the API does not support real-time preview of the camera frame data. To obtain the frame data, you must bind an action, for example, photographing.
**Solution**
Create a dual-channel preview to obtain the frame data.
1. Use the XComponent to create a preview stream.
```
// Obtain a PreviewOutput instance.
const surfaceId = globalThis.mxXComponentController.getXComponentSurfaceld();
this.mPreviewOutput = await Camera.createPreviewOutput(surfaceld) ;
```
2. Use imageReceiver to listen for image information.
```
// Add dual-channel preview.
const fullWidth = this.mFullScreenSize.width;
const fullHeight = this.mFullScreenSize.height;
const imageReceiver = await image.createImageReceiver(fullwidth, fullHeight,
formatImage, capacityImage) ;
const photoSurfaceId = await imageReceiver.getReceivingSurfaceld();
this.mPreviewOutputDouble = await Camera.createPreviewOutput ( photoSurfaceld)
```
## How do I obtain the preview image of the front camera?
Applicable to: OpenHarmony 3.2 (API version 9, stage model)
**Solution**
1. Use the **@ohos.multimedia.camera** module to obtain the physical camera information.
```
let cameraManager = await camera.getCameraManager(context);
let camerasInfo = await cameraManager.getSupportedCameras();
let cameraDevice = this.camerasInfo[0];
```
2. Create and start the input stream channel of the physical camera.
```
let cameraInput = await cameraManager.createCameraInput(cameraDevice);
await this.cameraInput.open();
```
3. Obtain the output formats supported by the camera, and create a preview output channel based on the surface ID provided by the XComponent.
```
let outputCapability = await this.cameraManager.getSupportedOutputCapability(cameraDevice);
let previewProfile = this.outputCapability.previewProfiles[0];
let previewOutput = await cameraManager.createPreviewOutput(previewProfile, previewId);
```
4. Create a camera session, add the camera input stream and preview output stream to the session, and start the session. The preview image is displayed on the XComponent.
```
let captureSession = await cameraManager.createCaptureSession();
await captureSession.beginConfig();
await captureSession.addInput(cameraInput);
await captureSession.addOutput(previewOutput);
await this.captureSession.commitConfig()
await this.captureSession.start();
```
## How do I set the camera focal length?
Applicable to: OpenHarmony 3.2 (API version 9, stage model)
**Solution**
1. Check whether the camera is a front camera. A front camera does not support focal length setting.
2. Use **captureSession.getZoomRatioRange\(\)** to obtain the focal length range supported by the device.
3. Check whether the target focal length is within the range obtained. If yes, call **captureSession.setZoomRatio\(\)** to set the focal length.
## How do I play music in the background?
Applicable to: OpenHarmony 3.2 (API version 9, stage model)
**Symptom**
Music cannot be played in the background.
**Solution**
**AVSession** controls media playback. When a third-party application switches to the background or encounters a screen lock event, media playback is forcibly paused and the application is unaware of the pause. To enable the application to continue the playback in the background, request a continuous task and access the AVSession capability, which allows Control Panel to control the playback behavior of third-party applications.
**Reference**
[Continuous Task Development](../task-management/continuous-task-dev-guide.md)
[AVSession Development](../media/using-avsession-developer.md)
## What should I do when multiple video components cannot be used for playback?
Applicable to: OpenHarmony 3.2 (API version 9, stage model)
**Symptom**
A large number of video components are created. They cannot play media normally or even crash.
**Solution**
A maximum of 13 media player instances can be created.
## How do I invoke the image library directly?
Applicable to: OpenHarmony 3.2 (API version 9, stage model)
**Solution**
```
let want = {
bundleName: 'com.ohos.photos',
abilityName: 'com.ohos.photos.MainAbility',
parameters: {
uri: 'detail'
}
};
let context = getContext(this) as common.UIAbilityContext;
context.startAbility(want);
```
此差异已折叠。
# Basic Security Capability Development
## What is the maximum number of bytes that can be encrypted at a time in AES GCM mode in HUKS?
Applicable to: OpenHarmony 3.1 Beta 5 (API version 9)
**Solution**
In HUKS, a maximum of 64 bytes can be encrypted at a time in AES GCM mode.
**Example**
```
/* Encrypt the key. */
await huks.init(srcKeyAlias, encryptOptions).then((data) => {
console.info(`test init data: ${JSON.stringify(data)}`);
handle = data.handle;
}).catch((err) => {
console.info('test init err information: ' + JSON.stringify(err));
});
encryptOptions.inData = aesCipherStringToUint8Array(cipherInData.slice (0,64)); // Take 64 bytes.
await huks.update(handle, encryptOptions).then(async (data) => {
console.info(`test update data ${JSON.stringify(data)}`);
encryptUpdateResult = Array.from(data.outData);
}).catch((err) => {
console.info('test update err information: ' + err);
});
encryptOptions.inData = aesCipherStringToUint8Array(cipherInData.slice (64,80)); // Remaining data
```
## What if garbled characters are returned by **digest()** of **Md** in Crypto framework?
Applicable to: OpenHarmony 3.1 Beta 5 (API version 9)
**Symptom**
In the CryptoFramework, garbled characters are returned by **digest()** of **Md**.
**Solution**
The DataBlob returned by **digest()** is of the Uint8Array type and needs to be converted into a hexadecimal string before being printed. You can use the online MD5 encryption tool to verify the result.
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
此差异已折叠。
Markdown is supported
0% .
You are about to add 0 people to the discussion. Proceed with caution.
先完成此消息的编辑!
想要评论请 注册