[Context](../reference/apis/js-apis-inner-application-context.md) is the context of an object in an application. It provides basic information about the application, for example, **resourceManager**, **applicationInfo**, **dir** (application development path), and **area** (encrypted level). It also provides basic methods such as **createBundleContext()** and **getApplicationContext()**. The UIAbility component and ExtensionAbility derived class components have their own **Context** classes, for example, the base class **Context**, **ApplicationContext**, **AbilityStageContext**, **UIAbilityContext**, **ExtensionContext**, and **ServiceExtensionContext**.
[Context](../reference/apis/js-apis-inner-application-context.md) is the context of an object in an application. It provides basic information about the application, for example, **resourceManager**, **applicationInfo**, **dir** (application file path), and **area** (encryption level). It also provides basic methods such as **createBundleContext()** and **getApplicationContext()**. The UIAbility component and ExtensionAbility derived class components have their own **Context** classes, for example, the base class **Context**, **ApplicationContext**, **AbilityStageContext**, **UIAbilityContext**, **ExtensionContext**, and **ServiceExtensionContext**.
- The figure below illustrates the inheritance relationship of contexts.
- The figure below illustrates the inheritance relationship of contexts.
- The figure below illustrates the holding relationship of contexts.
- The figure below illustrates the holding relationship of contexts.
The following describes the information provided by different contexts.
- The following describes the information provided by different contexts.
-[UIAbilityContext](../reference/apis/js-apis-inner-application-uiAbilityContext.md): Each UIAbility has the **Context** attribute, which provides APIs to operate an application component, obtain the application component configuration, and more.
```ts
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@@ -67,79 +70,81 @@ The following describes the information provided by different contexts.
This topic describes how to use the context in the following scenarios:
-[Obtaining the Application Development Path](#obtaining-the-application-development-path)
-[Obtaining and Modifying Encryption Levels](#obtaining-and-modifying-encryption-levels)
-[Creating Context of Another Application or Module](#creating-context-of-another-application-or-module)
-[Subscribing to UIAbility Lifecycle Changes in a Process](#subscribing-to-uiability-lifecycle-changes-in-a-process)
### Obtaining the Application Development Path
### Obtaining Application File Paths
The following table describes the application development paths obtained from context.
The base class [Context](../reference/apis/js-apis-inner-application-context.md) provides the capability of obtaining application file paths. **ApplicationContext**, **AbilityStageContext**, **UIAbilityContext**, and **ExtensionContext** inherit this capability. The application file paths are a type of application sandbox paths. For details, see [Application Sandbox Directory](../file-management/app-sandbox-directory.md).
**Table 1** Application development paths
The application file paths obtained by the preceding contexts are different.
| bundleCodeDir | string | Yes | No | Path for storing the application's installation package, that is, installation directory of the application on the internal storage. |
| cacheDir | string | Yes| No| Path for storing the cache files, that is, cache directory of the application on the internal storage.<br>It is the content of **Storage** of an application under **Settings > Apps & services > Apps**.|
| filesDir | string | Yes | No | Path for storing the common files, that is, file directory of the application on the internal storage.<br>Files in this directory may be synchronized to other directories during application migration or backup.|
| preferencesDir | string | Yes | Yes | Path for storing the preference files, that is, preferences directory of the application. |
| tempDir | string | Yes | No | Path for storing the temporary files.<br>Files in this directory are deleted after the application is uninstalled.|
| databaseDir | string | Yes | No | Path for storing the application's database, that is, storage directory of the local database. |
| distributedFilesDir | string | Yes| No| Path for storing the distributed files.|
- The application file path obtained through **ApplicationContext** is at the application level. This path is recommended for storing global application information, and the files in the path will be deleted when the application is uninstalled.
The capability of obtaining the application development path is provided by the base class **Context**. This capability is also provided by **ApplicationContext**, **AbilityStageContext**, **UIAbilityContext**, and **ExtensionContext**. However, the paths obtained from different contexts may differ, as shown below.
**Figure 1** Application development paths obtained from context
- Obtain the application-level path through **ApplicationContext**. It is recommended that global application information be stored in this path. Files stored in this path will be deleted only when the application is uninstalled.
- Obtain the HAP level path through **AbilityStageContext**, **UIAbilityContext**, and **ExtensionContext**. It is recommended that the HAP information be stored in this path. The file content stored in this path will be deleted when the HAP is uninstalled. The file content in the application-level path will be deleted only after all the HAPs of the application are uninstalled.
import UIAbility from '@ohos.app.ability.UIAbility';
export default class EntryAbility extends UIAbility {
onCreate(want, launchParam) {
let applicationContext = this.context.getApplicationContext();
let cacheDir = applicationContext.cacheDir;
let tempDir = applicationContext.tempDir;
let filesDir = applicationContext.filesDir;
let databaseDir = applicationContext.databaseDir;
let bundleCodeDir = applicationContext.bundleCodeDir;
let distributedFilesDir = applicationContext.distributedFilesDir;
let preferencesDir = applicationContext.preferencesDir;
...
}
}
```
The sample code for obtaining the application development paths is as follows:
- The application file path obtained through **AbilityStageContext**, **UIAbilityContext**, or **ExtensionContext** is at the HAP level. This path is recommended for storing HAP-related information, and the files in this path are deleted when the HAP is uninstalled. However, the deletion does not affect the files in the application-level path unless all HAPs of the application are uninstalled.
> The sample code obtains the sandbox path of the application development path. The absolute path can be obtained by running the **find / -name <fileName>** command in the hdc shell after file creation or modification.
### Obtaining and Modifying Encryption Levels
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@@ -153,22 +158,23 @@ In practice, you need to select a proper encryption level based on scenario-spec
>
> - AreaMode.EL2: user-level encryption. Directories with this encryption level are accessible only after the device is powered on and the password is entered (for the first time).
You can obtain and set the encryption level by reading and writing the [area attribute in Context](../reference/apis/js-apis-inner-application-context.md).
You can obtain and set the encryption level by reading and writing the **area** attribute in [Context](../reference/apis/js-apis-inner-application-context.md).
### Creating Context of Another Application or Module
The base class **Context** provides [createBundleContext(bundleName:string)](../reference/apis/js-apis-inner-application-context.md#contextcreatebundlecontext), [createModuleContext(moduleName:string)](../reference/apis/js-apis-inner-application-context.md#contextcreatemodulecontext), and [createModuleContext(bundleName:string, moduleName:string)](../reference/apis/js-apis-inner-application-context.md#contextcreatemodulecontext-1) to create the context of other applications or modules, so as to obtain the resource information, for example, [obtaining the application development paths](#obtaining-the-application-development-path) of other modules.
The base class **Context** provides [createBundleContext(bundleName:string)](../reference/apis/js-apis-inner-application-context.md#contextcreatebundlecontext), [createModuleContext(moduleName:string)](../reference/apis/js-apis-inner-application-context.md#contextcreatemodulecontext), and [createModuleContext(bundleName:string, moduleName:string)](../reference/apis/js-apis-inner-application-context.md#contextcreatemodulecontext-1) to create the context of other applications or modules, so as to obtain the resource information, for example, [obtaining application file paths](#obtaining-application-development-paths) of other modules.
- Call **createBundleContext(bundleName:string)** to create the context of another application.
> **NOTE**
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@@ -188,9 +194,9 @@ The base class **Context** provides [createBundleContext(bundleName:string)](../
> - Request the **ohos.permission.GET_BUNDLE_INFO_PRIVILEGED** permission. For details, see [Declaring Permissions in the Configuration File](../security/accesstoken-guidelines.md#declaring-permissions-in-the-configuration-file).
>
> - This is a system API and cannot be called by third-party applications.
For example, application information displayed on the home screen includes the application name and icon. The home screen application calls the foregoing method to obtain the context information, so as to obtain the resource information including the application name and icon.
```ts
importUIAbilityfrom'@ohos.app.ability.UIAbility';
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@@ -203,7 +209,7 @@ The base class **Context** provides [createBundleContext(bundleName:string)](../
}
}
```
- Call **createModuleContext(bundleName:string, moduleName:string)** to obtain the context of a specified module of another application. After obtaining the context, you can obtain the resource information of that module.
@@ -17,11 +17,13 @@ This document describes the following operations:
## Setting a Mission Snapshot Icon (for System Applications Only)
Call [UIAbilityContext.setMissionIcon()](../reference/apis/js-apis-inner-application-uiAbilityContext.md#uiabilitycontextsetmissionicon) to set the icon of a mission snapshot. The icon is an object of the [PixelMap](../reference/apis/js-apis-image.md#pixelmap7) type. For details about how to obtain the context, see [Obtaining the Context of UIAbility](uiability-usage.md#obtaining-the-context-of-uiability).
Call [UIAbilityContext.setMissionIcon()](../reference/apis/js-apis-inner-application-uiAbilityContext.md#uiabilitycontextsetmissionicon) to set the icon of a mission snapshot. For details about how to obtain the context, see [Obtaining the Context of UIAbility](uiability-usage.md#obtaining-the-context-of-uiability). For details about how to obtain the PixelMap information in the example, see [Image Decoding](../media/image-decoding.md).
```ts
letimagePixelMap:PixelMap=undefined;// Obtain the PixelMap information.
letcontext=...;// UIAbilityContext
letpixelMap:PixelMap=...;// PixelMap information of the image.
context.setMissionIcon(imagePixelMap,(err)=>{
context.setMissionIcon(pixelMap,(err)=>{
if(err.code){
console.error(`Failed to set mission icon. Code is ${err.code}, message is ${err.message}`);
Call [UIAbilityContext.setMissionLabel()](../reference/apis/js-apis-inner-application-uiAbilityContext.md#uiabilitycontextsetmissionlabel) to set the name of a mission snapshot.
```ts
this.context.setMissionLabel('test').then(()=>{
letcontext=...;// UIAbilityContext
context.setMissionLabel('test').then(()=>{
console.info('Succeeded in seting mission label.');
}).catch((err)=>{
console.error(`Failed to set mission label. Code is ${err.code}, message is ${err.message}`);
@@ -5,12 +5,11 @@ The OpenHarmony process model is shown below.
- All UIAbility, ServiceExtensionAbility, and DataShareExtensionAbility components of an application (with the same bundle name) run in an independent process, which is **Main process** in green in the figure.
- The ExtensionAbility components of the same type (except ServiceExtensionAbility and DataShareExtensionAbility) of an application (with the same bundle name) run in an independent process, which is **FormExtensionAbility process**, **InputMethodExtensionAbility process**, and other **ExtensionAbility process** in blue in the figure.
- All ExtensionAbility components of the same type (except ServiceExtensionAbility and DataShareExtensionAbility) of an application (with the same bundle name) run in an independent process, which is **FormExtensionAbility process**, **InputMethodExtensionAbility process**, and other **ExtensionAbility process** in blue in the figure.
- WebView has an independent rendering process, which is **Render process** in yellow in the figure.
**Figure 1** Process model
**Figure 1** Process model
> NOTE
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@@ -20,7 +19,8 @@ The OpenHarmony process model is shown below.
A system application can apply for multi-process permissions (as shown in the following figure) and configure a custom process for an HAP. UIAbility, DataShareExtensionAbility, and ServiceExtensionAbility in the HAP run in the custom process. Different HAPs run in different processes by configuring different process names.
@@ -4,19 +4,18 @@ For an OpenHarmony application, each process has a main thread to provide the fo
- Draw the UI.
- Manage the ArkTS engine instance of the main thread so that multiple UIAbility components can run on it.
- Manage ArkTS engine instances of other threads (such as the worker thread), for example, starting and terminating other threads.
- Manage ArkTS engine instances of other threads, for example, starting and terminating other threads.
- Distribute interaction events.
- Process application code callbacks (event processing and lifecycle management).
- Receive messages sent by the worker thread.
In addition to the main thread, there is an independent thread, named worker. The worker thread is mainly used to perform time-consuming operations. The worker thread is created in the main thread and is independent from the main thread. It cannot directly operate the UI. A maximum of seven worker threads can be created.
Based on the OpenHarmony thread model, different services run on different threads. Service interaction requires inter-thread communication. In the same process, threads can communicate with each other in Emitter or Worker mode. Emitter is mainly used for event synchronization between threads, and Worker is mainly used to execute time-consuming tasks.
> **NOTE**
>
>
> - The stage model provides only the main thread and worker thread. Emitter is mainly used for event synchronization within the worker thread or between the main thread and worker thread.
> - The UIAbility and UI are in the main thread. For details about data synchronization between them, see [Data Synchronization Between UIAbility and UI](uiability-data-sync-with-ui.md).
> - To view thread information about an application process, run the **hdc shell** command to enter the shell CLI of the device, and then run the **ps -p *<pid>* -T command**, where *<pid>* indicates the [process ID](process-model-stage.md) of the application.
