Multicast DNS (mDNS) provides functions such as adding, removing, discovering, and resolving local services on a LAN.
- Local service: a service provider on a LAN, for example, a printer or scanner.
Typical MDNS management scenarios include:
- Managing local services on a LAN, such as adding, removing, and resolving local services.
- Discovering local services and listening to the status changes of local services of the specified type through the **DiscoveryService** object.
> **NOTE**
> To maximize the application running efficiency, most API calls are called asynchronously in callback or promise mode. The following code examples use the callback mode. For details about the APIs, see [mDNS Management](../reference/apis/js-apis-net-mdns.md).
The following describes the development procedure specific to each application scenario.
## Available APIs
For the complete list of APIs and example code, see [mDNS Management](../reference/apis/js-apis-net-mdns.md).
| Type| API| Description|
| ---- | ---- | ---- |
| ohos.net.mdns | addLocalService(context: Context, serviceInfo: LocalServiceInfo, callback: AsyncCallback\<LocalServiceInfo>): void | Adds an mDNS service. This API uses an asynchronous callback to return the result.|
| ohos.net.mdns | removeLocalService(context: Context, serviceInfo: LocalServiceInfo, callback: AsyncCallback\<LocalServiceInfo>): void | Removes an mDNS service. This API uses an asynchronous callback to return the result.|
| ohos.net.mdns | createDiscoveryService(context: Context, serviceType: string): DiscoveryService | Creates a **DiscoveryService** object, which is used to discover mDNS services of the specified type.|
| ohos.net.mdns | resolveLocalService(context: Context, serviceInfo: LocalServiceInfo, callback: AsyncCallback\<LocalServiceInfo>): void | Resolves an mDNS service. This API uses an asynchronous callback to return the result.|
| ohos.net.mdns.DiscoveryService | startSearchingMDNS(): void | Searches for mDNS services on the LAN.|
| ohos.net.mdns.DiscoveryService | stopSearchingMDNS(): void | Stops searching for mDNS services on the LAN.|
-[HTTP data request](http-request.md): Initiates a data request through HTTP.
-[WebSocket connection](websocket-connection.md): Establishes a bidirectional connection between the server and client through WebSocket.
-[Socket connection](socket-connection.md): Transmits data through Socket.
-[Network policy management](net-policy-management.md): Restricts network capabilities by setting network policies, including cellular network policy, sleep/power-saving mode policy, and background network policy, and resets network policies as needed.
-[Network sharing](net-sharing.md): Shares a device's Internet connection with other connected devices by means of Wi-Fi hotspot, Bluetooth, and USB sharing, and queries the network sharing state and shared mobile data volume.
-[Ethernet connection](net-ethernet.md): Provides wired network capabilities, which allow you to set the IP address, subnet mask, gateway, and Domain Name System (DNS) server of a wired network.
-[Network connection management](net-connection-manager.md): Provides basic network management capabilities, including management of Wi-Fi/cellular/Ethernet connection priorities, network quality evaluation, subscription to network connection status changes, query of network connection information, and DNS resolution.
-[HTTP data request](http-request.md): initiates a data request through HTTP.
-[WebSocket connection](websocket-connection.md): establishes a bidirectional connection between the server and client through WebSocket.
-[Socket connection](socket-connection.md): transmits data through Socket.
-[Network policy management](net-policy-management.md): restricts network capabilities by setting network policies, including cellular network policy, sleep/power-saving mode policy, and background network policy, and resets network policies as needed.
-[Network sharing](net-sharing.md): shares a device's Internet connection with other connected devices by means of Wi-Fi hotspot, Bluetooth, and USB sharing, and queries the network sharing state and shared mobile data volume.
-[Ethernet connection](net-ethernet.md): provides wired network capabilities, which allow you to set the IP address, subnet mask, gateway, and Domain Name System (DNS) server of a wired network.
-[Network connection management](net-connection-manager.md): provides basic network management capabilities, including management of Wi-Fi/cellular/Ethernet connection priorities, network quality evaluation, subscription to network connection status changes, query of network connection information, and DNS resolution.
-[mDNS management](net-mdns.md): provides Multicast DNS (mDNS) management capabilities, such as adding, removing, discovering, and resolving local services on a LAN.
@@ -9,7 +9,7 @@ Application recovery helps to restore the application state and save temporary d
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.
In API version 10, application recovery is also supported for multiple abilities of the 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.
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.
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**.
## What are the data formats supported by extraData in an HTTP request?
Applicable to: OpenHarmony SDK 3.2.2.5, stage model of API version 9
**extraData** indicates additional data in an HTTP request. It varies depending on the HTTP request method.
- If the HTTP request uses a POST or PUT method, **extraData** serves as the content of the HTTP request.
- If the HTTP request uses a GET, OPTIONS, DELETE, TRACE, or CONNECT method, **extraData** serves as a supplement to the HTTP request parameters and will be added to the URL when the request is sent.
- If you pass in a string object, **extraData** contains the string encoded on your own.
## What does error code 28 mean for an HTTP request?
Applicable to: OpenHarmony SDK 3.2.2.5, stage model of API version 9
Error code 28 refers to **CURLE_OPERATION_TIMEDOUT**, which means a cURL operation timeout. For details, see any HTTP status code description available.
Reference: [Response Codes](../reference/apis/js-apis-http.md#responsecode) and [Curl Error Codes](https://curl.se/libcurl/c/libcurl-errors.html)
## What does error code 6 mean for the response of \@ohos.net.http.d.ts?
Applicable to: OpenHarmony SDK 3.2.3.5
Error code 6 indicates a failure to resolve the host in the address. You can ping the URL carried in the request to check whether the host is accessible.
Reference: [Response Codes](../reference/apis/js-apis-http.md#responsecode) and [Curl Error Codes](https://curl.se/libcurl/c/libcurl-errors.html)
Applicable to: OpenHarmony SDK 3.2.3.5, stage model of API version 9
Run the hdc_std command to copy the .db, .db-shm, and .db-wal files in **/data/app/el2/100/database/*bundleName*/entry/db/**, and then use the SQLite tool to open the files.
Applicable to: OpenHarmony SDK 3.2.5.5, stage model of API version 9
The distributed data service (DDS), relational database (RDB) store, and preferences provided OpenHarmony have a lock mechanism. You do not need to bother with the lock mechanism during the development.
## What Is a Transaction in an RDB Store?
Applicable to: all versions
When a large number of operations are performed in an RDB store, an unexpected exception may cause a failure of some data operations and loss of certain data. As a result, the application may become abnormal or even crash.
A transaction is a group of tasks serving as a single logical unit. It eliminates the failure of some of the operations and loss of associated data.
## What Data Types Does an RDB Store Support?
Applicable to: OpenHarmony SDK 3.0 or later, stage model of API version 9
An RDB store supports data of the number, string, and Boolean types. The number array supports data of the Double, Long, Float, Int, or Int64 type, with a maximum precision of 17 decimal digits.
## How Do I View Database db Files?
Applicable to: OpenHarmony SDK 3.2.6.5, stage model of API version 9
1. Run the **hdc_std shell** command.
2. Obtain the absolute path or sandbox path of the database.
The absolute path is **/data/app/el2/<userId>/database/<bundleName>**. The default **<userId>** is **100**.
To obtain the sandbox path, run the **ps -ef | grep hapName** command to obtain the process ID of the application.
The database sandbox path is **/proc/<Application process ID>/root/data/storage/el2/database/**.
3. Run the **find ./ -name "\*.db"** command in the absolute path or sandbox path of the database.
## How Do I Store Long Text Data?
Applicable to: OpenHarmony SDK 3.2.5.5, API version 9
- Preferences support a string of up to 8192 bytes.
- The KV store supports a value of up to 4 MB.
Reference: [Preference Overview](../database/database-preference-overview.md) and [Distributed Data Service Overview](../database/database-mdds-overview.md)
## How Do I Develop DataShare on the Stage Model
Applicable to: OpenHarmony SDK 3.2.5.5, API version 9
The DataShare on the stage model cannot be used with the **DataAbility** for the FA model. The connected server application must be implemented by using **DataShareExtensionAbility**.
## How do I take screenshots on a development board?
Applicable to: OpenHarmony SDK 3.2.2.5, stage model of API version 9
- Method 1: Click the screenshot button in the Control Panel from the development board UI. The screenshot is displayed in Gallery.
- Method 2: Run the screenshot script. Connect to the development board to a computer running Windows. Create a text file on the computer, copy the following script content to the file, change the file name extension to **.bat** (the HDC environment variables must be configured in advance), and click **Run**. The screenshot is saved to the same directory as the **.bat** script file.
Example:
```
set filepath=/data/%date:~0,4%%date:~5,2%%date:~8,2%%time:~1,1%%time:~3,2%%time:~6,2%.png
echo %filepath%
: pause
hdc_std shell snapshot_display -f %filepath%
: pause
hdc_std file recv %filepath% .
: pause
```
## How do I adjust Previewer in DevEco Studio so that the preview looks the same as what's displayed on a real RK3568 development board?
## What should I do if Device Manager incorrectly identifies a development board as FT232R USB UART even when the development board already has a driver installed?
Possible cause: The USB serial driver of the development version is not installed.
Solution: Search for **FT232R USB UART**, and download and install the driver.
## How do I complete authentication when logging in to the development board?
Applicable to: OpenHarmony SDK 3.2.2.5
When connecting to the network that requires authentication, open any web page in the browser to access the authentication page.
If there is no browser on the development board, you can install the [sample browser application](https://gitee.com/openharmony/app_samples/tree/master/device/Browser).
## How do I locate the fault when the application crashes?
## How do I flush HiLog information to disks?
Applicable to: OpenHarmony SDK 3.2.5.5
Applicable to: OpenHarmony 3.2 Beta (API version 9)
1. Locate the crash-related code based on the service log.
**Symptom**
2. View the error information in the crash file, which is located at **/data/log/faultlog/faultlogger/**.
How do I flush HiLog information to disks?
## Why cannot access controls in the UiTest test framework?
**Solution**
Applicable to: OpenHarmony SDK 3.2.5.5
Run the **hilog -w start -f ckTest -l 1M -n 5 -m zlib -j 11** command.
Check whether **persist.ace.testmode.enabled** is turned on.
The log file is saved in the **/data/log/hilog/** directory.
Run **hdc\_std shell param get persist.ace.testmode.enabled**.
Parameter description:
If the value is **0**, run the **hdc\_std shell param set persist.ace.testmode.enabled 1** to enable the test mode.
## Why is private displayed in logs when the format parameter type of HiLog in C++ code is %d or %s?
When format parameters such as **%d** and **%s** are directly used, the standard system uses **private** to replace the actual data for printing by default to prevent data leakage. To print the actual data, replace **%d** with **%{public}d** or replace **%s** with **%{public}s**.
## What should I do if the hilog.debug log cannot be printed?
Applicable to: OpenHarmony SDK 3.2.5.5, stage model of API version 9
Run **hdc_std shell hilog -b D** to turn on the debugging switch.
## Is HiLog or console recommended for log printing? How do I set the domain if HiLog is used?
Applicable to: OpenHarmony SDK 3.2.2.5
You are advised to use the [HiLog](../reference/apis/js-apis-hilog.md) for log printing. For details about how to set the **domain** parameter, see the [Development Guide](../reference/apis/js-apis-hilog.md#hilogisloggable).
## What is the maximum length of a log record when HiLog is used? Is it configurable?
Applicable to: OpenHarmony SDK 3.2.2.5
The maximum length of a log record is 1,024 characters, and it is not changeable.
## Can I separate multiple strings by spaces in the tag parameter of the HiLog API?
Applicable to: OpenHarmony SDK 3.2.6.5, stage model of API version 9
No. Separating multiple strings by spaces is not allowed.
## How do I print real data if HiLog does not contain data labeled by {public}?
Applicable to: OpenHarmony SDK 3.2.6.5, stage model of API version 9
Run **hdc\_std shell hilog -p off** to disable logging of data labeled by {public}.
```
-**-w**: Starts a log flushing task. **start** means to start the task, and **stop** means to stop the task.
-**-f**: Sets the log file name.
-**-l**: Sets the size of a single log file. The unit can be B, KB, MB, or GB.
-**-n**: Sets the maximum number of log files. When the number of log files exceeds the specified value, the earliest log file will be overwritten. The value range is [2,1000].
-**-m**: Specifies the log file compression algorithm.
-**-j**: Specifies the task ID. The value ranges from **10** to **0xffffffffff**.
For more details about parameters, run the **hilog --help** command.
## How do I read an XML file in rawfile and convert the data in it to the string type?
Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)
**Solution**
Call **getRawFileContent** of the **ResourceManager** module to obtain the data in the XML file, and then use **String.fromCharCode** to convert the data to the string type.
Applicable to: OpenHarmony 3.1 Beta 5 (API version 9)
**Solution**
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 mode does not apply to the FA model.
**Sample Code**
```
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 the path of the resource directory by using an API?
Applicable to: OpenHarmony 3.1 Beta 5 (API version 9)
**Symptom**
How do I obtain the path of the **resource** directory so that I can manage the files in it by using the file management API?
**Solution**
Because the application is installed in HAP mode and the HAP package is not decompressed after the installation is complete, the resource path cannot be obtained when the program is running.
To obtain the path of the **resource** directory, try either of the following ways:
1. Use **\$r** or **\$rawfile** for access. This method applies to static access, during which the **resource** directory remains unchanged when the application is running.
2. Use **ResourceManager** for access. This method applies to dynamic access, during which the **resource** directory dynamically changes when the application is running.
**Reference**
[Resource Categories and Access](../quick-start/resource-categories-and-access.md) and [Resource Manager](../reference/apis/js-apis-resource-manager.md)
## Why does getPluralString return an incorrect value?
Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)
**Symptom**
The value obtained by the **getPluralString** is **other**, which is incorrect.
**Solution**
The **getPluralString** API is effective only when the system language is English.
## How do I obtain the customized string fields in the resources directory?
Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)
**Solution**
Use **getStringValue** of the **ResourceManager** module.
## How do I reference resources such as images and text in AppScope?
Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)
**Solution**
Reference resources in the **\$r\('app.type.name'\)** format. Wherein, **type** indicates the resource type, such as color, string, and media, and **name** indicates the resource name.
## How do I convert resources to strings?
Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)
**Solution**
For a qualifier directory, use **this.context.resourceManager.getStringSync\(\$r\('app.string.test'\).id\)** to covert resources to strings synchronously. Note that the **\$r\('app.string.test', 2\)** mode is not supported.
## How resources in AppScope, such as images and text, are referenced?
Applicable to: OpenHarmony SDK 3.2.5.5, stage model of API version 9
Resources are referenced in the **$r('app.type.name')** format. Where, **type** indicates the resource type, such as color, string, and media, and **name** indicates the resource name.
## How do I convert the resource type to string?
Applicable to: OpenHarmony SDK3.0, stage model of API version 9
If the resource type is set to **string**, the qualifier directory can be set as **this.context.resourceManager.getStringSync(\\$r('app.string.test').id)** and can be converted synchronously. The **\$r('app.string.test', 2)** mode is not supported. For more usage methods, see [Resource Manager](../reference/apis/js-apis-resource-manager.md#getstringsync9).
## Why should I do if the constants referenced by $ in the form_config.json file does not take effect?
Applicable to: OpenHarmony SDK 3.2.6.5, API9 Stage model
In the **form\_config.json** file, **$** cannot be used to reference constants.
@@ -85,8 +85,6 @@ 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.
Reference: [State Management with Application-level Variables](../quick-start/arkts-state-mgmt-application-level.md)
## How do I obtain resources in the stage model?
Applicable to: OpenHarmony SDK 3.2.3.5, stage model of API version 9
...
...
@@ -181,7 +179,7 @@ Similar to **new Date().getTime()**, **systemTime.getCurrentTime(false)** return
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: () => 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**). For details, see [BuilderParam](../quick-start/arkts-dynamic-ui-elememt-building.md#builderparam8).
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: () => 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?
...
...
@@ -251,7 +249,6 @@ 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
## What are the data formats supported by extraData in an HTTP request?
Applicable to: OpenHarmony 3.2 Beta (API version 9)
**Solution**
**extraData** indicates additional data in an HTTP request. It varies depending on the HTTP request method.
- If the HTTP request uses a POST or PUT method, **extraData** serves as the content of the HTTP request.
- If the HTTP request uses a GET, OPTIONS, DELETE, TRACE, or CONNECT method, **extraData** serves as a supplement to the HTTP request parameters and will be added to the URL when the request is sent.
- If you pass in a string object, **extraData** contains the string encoded on your own.
## What does error code 28 mean in the response to an HTTP request?
Applicable to: OpenHarmony 3.2 Beta (API version 9)
**Symptom**
Error code 28 is reported after an HTTP request is initiated.
**Solution**
Error code 28 indicates **CURLE\_OPERATION\_TIMEDOUT**, which means a libcurl library operation timeout. For details, see any HTTP status code description available.
**Reference**
[Common HTTP Response Codes](../reference/apis/js-apis-http.md#responsecode) and [Curl Error Codes](https://curl.se/libcurl/c/libcurl-errors.html)
## What does error code 6 mean in the response to an HTTP request?
Applicable to: OpenHarmony 3.2 Beta (API version 9)
**Symptom**
Error code 6 is reported after an HTTP request is initiated.
**Solution**
Error code 6 indicates a failure to resolve the host in the address. You can ping the URL carried in the request to check whether the host is accessible.
**Reference**
[Common HTTP Response Codes](../reference/apis/js-apis-http.md#responsecode) and [Curl Error Codes](https://curl.se/libcurl/c/libcurl-errors.html)
## How are parameters passed to queryParams of the POST request initiated by @ohos/axios?
Applicable to: OpenHarmony 3.2 Beta (API version 9)
**Symptom**
How are parameters passed to **queryParams** when the third-party component @ohos/axios initiates a POST request?
**Solution**
- Method 1: Have the **axios.post** API receive only one parameter. The **Url.URLSearchParams** parameter needs to be converted into a string and appended to the end of the URL.
```
let params:Url.URLSearchParams = new Url.URLSearchParams()
## What should I do if no data is returned after connection.getNetCapabilities\(mNetHandle\) is called?
Applicable to: OpenHarmony 3.2 Beta 2 (API version 9)
**Symptom**
No data is returned after **connection.getNetCapabilities\(\)** is called. What should I do?
**Possible Cause**
This problem is due to incorrect pointing of the **this** object. You are expected to use **\(err,data\)=\>\{\}** instead of **function\(err,data\)** to access the callback function to obtain the return result. The reason is that the function declared by **function** has its own **this** object and therefore cannot point to the **globalThis** object.
**Solution**
Change **function\(err,data\)** to **\(err,data\)** for the second parameter of **getNetCapabilities**.
## How is data in HTTP requests transmitted in JSON format?
Applicable to: OpenHarmony 3.2 Beta (API version 9)
**Solution**
In the HTTP message header, **Content-Type** is used to indicate the media type information. It tells the server how to process the requested data and tells the client (usually a browser) how to parse the response data, for example, displaying an image, parsing HTML, or displaying only the text.
To transmit data in HTTP requests in JSON format, set **Content-Type** to **application/json**.
```
this.options = {
method: http.RequestMethod.GET,
extraData: this.extraData,
header: { 'Content-Type': 'application/json' },
readTimeout: 50000,
connectTimeout: 50000
}
```
## How do I upload photos taken by a camera to the server?
Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)
**Symptom**
After an application calls the camera to take a photo, how do I upload the photo to the server?
**Solution**
After the application is started and the permission is obtained, have the system access the remote server and transfer the locally saved photos to the remote server through the upload API.
**Reference**
[Upload and Download](../reference/apis/js-apis-request.md)
## What should I do if calling connection.hasDefaultNet\(\) fails even when the network is normal?
Applicable to: OpenHarmony 3.2 Beta (API version 9)
**Symptom**
The network connection is normal, and web pages can be opened properly on the browser. However, calling the **hasDefaultNet** fails, and the callback function returns an error.
**Solution**
Declare the **ohos.permission.GET\_NETWORK\_INFO** permission when calling **connection.hasDefaultNet**.
For details, see [Applying for Permissions](../security/accesstoken-guidelines.md).
## What does netId mean in the netHandle object returned by connection.getDefaultNet?
Applicable to: OpenHarmony 3.2 Beta (API version 9)
**Symptom**
What are the meanings of the values of **netId**, such as **0** and **100**?
**Solution**
If the value of **netId** is **0**, no network connection is available. In such a case, check and rectify network faults. If the value is greater than or equal to **100**, the network connection is normal.
## How do I use HTTP requests to obtain data from the network?
Applicable to: OpenHarmony 3.2 Beta (API version 9)
**Solution**
Use the **@ohos.net.http** module to initiate an HTTP request.
1. Import the **http** module and create an HTTP request.
2. Set the request URL and parameters and initiate the HTTP request.
3. Obtain the response and parse the data.
**Reference**
[HTTP Data Request](../connectivity/http-request.md)
## How do I encapsulate network requests by using JavaScript?
Applicable to: OpenHarmony 3.2 Beta (API version 9)
**Solution**
OpenHarmony supports the JavaScript development mode. You can directly use JavaScript to encapsulate network requests. For details, see [Network Connection](../reference/apis/js-apis-http.md).
## How do I write network requests when developing a JavaScript-based application for smart watches?
Applicable to: OpenHarmony 3.2 Beta (API version 9)
**Solution**
OpenHarmony supports the JavaScript development mode. You can directly use JavaScript to encapsulate network requests. For details, see [Network Connection](../reference/apis/js-apis-http.md).
## Why does an application fail to start after the ohos.permission.NOTIFICATION\_CONTROLLER permission is declared?
Applicable to: OpenHarmony 3.2 Beta (API version 9)
**Symptom**
When an application is started, the following error message is reported w: error: install failed due to grant request permissions failed.
**Solution**
The **ohos.permission.NOTIFICATION\_CONTROLLER** permission is a **system core** permission and is not available for third-party applications.
## What should I do if an error is reported when wifi.getIpInfo\(\).ipAddress is used in the Wi-Fi module?
Applicable to: OpenHarmony 3.2 Beta (API version 9)
**Symptom**
When **wifi.getIpInfo\(\).ipAddress** is used in the Wi-Fi module, the following error message is reported: Error: assertion \(wifiDevicePtr != nullptr\) failed: Wifi device instance is null.
**Solution**
This problem is due to insufficient permissions. Check whether you have applied for the required permissions. For details, see [Permission Management](../security/accesstoken-overview.md).
## How do I obtain the system version of a device?
Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)
**Solution**
You can obtain the system version of a device through the **osFullName** attribute of the [deviceInfo](../reference/apis/js-apis-device-info.md) object.
**Sample Code**
```
import deviceInfo from '@ohos.deviceInfo'
let v = deviceInfo.osFullName
```
## How do I obtain the UDID of a device?
Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)
**Solution**
- Method 1: Run the **hdc shell bm get --udid** command.
- Method 2: Obtain the value from the code. For details, see [udid](../reference/apis/js-apis-device-info.md).
## How do I obtain device information?
Applicable to: OpenHarmony 3.2 Beta 5 (API version 9)
You can call **deviceInfo** to obtain device information, such as the device model.
This document describes how to use the native Rawfile APIs to manage raw file directories and files in OpenHarmony. You can use the APIs to traverse, open, search for, read, and close raw files.
This document describes how to use the native Rawfile APIs to manage raw file directories and files in OpenHarmony. You can use Rawfile APIs to perform operations such as traversing the file list, opening, searching for, reading, and closing raw files.
| RawDir *OH_ResourceManager_OpenRawDir(const NativeResourceManager *mgr, const char *dirName) | Opens a raw file directory. |
...
...
@@ -27,60 +25,289 @@ This document describes how to use the native Rawfile APIs to manage raw file di
## How to Develop
1. Add the header file.
The following describes how to obtain the raw file list, raw file content, and raw file descriptor on the JavaScript side as an example.
1. Create a project.
2. Add dependencies.
After a project is created, the **cpp** directory is created under the project. The directory contains files such as **libentry/index.d.ts**, **hello.cpp**, and **CMakeLists.txt**.
1. Open the **src/main/cpp/CMakeLists.txt** file, and add **librawfile.z.so** and **libhilog_ndk.z.so** to **target_link_libraries**.
```c++
#include "raw_file_manager.h"
target_link_libraries(entry PUBLIC libace_napi.z.so libhilog_ndk.z.so librawfile.z.so)
```
2.Call **OH_ResourceManager_InitNativeResourceManager(napi_env env, napi_value jsResMgr)** to obtain a **NativeResourceManager** instance.
2.Open the **src/main/cpp/types/libentry/index.d.ts** file, and declare the application functions **getFileList**, **getRawFileContent**, and **getRawFileDescriptor**.
```js
// Import the JS resource manager from the JS head file and pass it to the C++ file.
1. Open the **src/main/cpp/hello.cpp** file. During initialization, the file maps the external JavaScript APIs **getFileList**, **getRawFileContent**, and **getRawFileDescriptor** to C++ native APIs **GetFileList**, **GetRawFileContent**, and **GetRawFileDescriptor**.
3. Obtain JavaScript resource objects from the **hello.cpp** file, and convert them to native resource objects. Then, call the native APIs to obtain the raw file list, raw file content, and raw file descriptor {fd, offset, length}. The sample code is as follows:
```c++
// Example 1: Use GetFileList to obtain the raw file list.
// Obtain argv[0], which specifies conversion of the JavaScript resource object (that is, OH_ResourceManager_InitNativeResourceManager) to a native object.
// Obtain argv[0], which specifies conversion of the JavaScript resource object (that is, OH_ResourceManager_InitNativeResourceManager) to a native object.
// Convert the native object to a JavaScript object.
return createJsFileDescriptor(env,descriptor);
}
```
4. Call APIs on the JavaScript side.
1. Open **src\main\ets\pages\index.ets**, and import **libentry.so**.
2. Obtain the JavaScript resource object, that is, **resourceManager**.
3. Call **getFileList**, that is, the native API declared in **src/main/cpp/types/libentry/index.d.ts**. When calling the API, pass the JavaScript resource object and the relative path of the raw file. The sample code is as follows:
```js
import hilog from '@ohos.hilog';
import testNapi from 'libentry.so' // Import the libentry.so file.
@Entry
@Component
struct Index {
@State message: string = 'Hello World'
private resmgr = getContext().resourceManager; // Obtain the JavaScript resource object.
The **geolocation** module provides a wide array of location services, including GNSS positioning, network positioning, geocoding, reverse geocoding, and geofencing.
> The APIs of this module are no longer maintained since API version 7. You are advised to use ['@ohos.hilog](js-apis-hilog.md)' instead.
The **console** module provides basic log printing capabilities and supports log printing by log level.
If you want to use more advanced log printing services, for example, filtering logs by the specified ID, you are advised to use [`@ohos.hilog`](js-apis-hilog.md).
> **NOTE**
>
> The initial APIs of this module are supported since API version 3. Newly added APIs will be marked with a superscript to indicate their earliest API version.
Switch to the HiLog window at the bottom of HUAWEI DevEco Studio. Specifically, select the current device and process, set the log level to Info, and enter Hello World in the search box. Logs that meet the search criteria are displayed, as shown in the following figure.
Starts a timer to track the duration of an operation. The default value is **default**. You can use **console.timeEnd()** to disable the timer and print the result.
@@ -13,7 +13,7 @@ The Resource Manager module provides APIs to obtain information about applicatio
importresourceManagerfrom'@ohos.resourceManager';
```
## How to Use
## Instruction
Since 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 approach, however, is not applicable to the FA model. For the FA model, you need to import the required bundle and then call the [getResourceManager](#resourcemanagergetresourcemanager) API to obtain a **ResourceManager** object.
For details about how to reference context in the stage model, see [Context in the Stage Model](../../application-models/application-context-stage.md).
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@@ -78,7 +78,7 @@ Obtains the **ResourceManager** object of an application based on the specified
| bundleName | string | Yes | Bundle name of the target application. |
| bundleName | string | Yes | Bundle name of the application. |
| callback | AsyncCallback<[ResourceManager](#resourcemanager)> | Yes | Callback used to return the result.|
**Example**
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@@ -135,7 +135,7 @@ Obtains the **ResourceManager** object of an application based on the specified
| Name | Type | Mandatory | Description |
| ---------- | ------ | ---- | ------------- |
| bundleName | string | Yes | Bundle name of the target application.|
| bundleName | string | Yes | Bundle name of the application.|
**Return value**
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@@ -171,12 +171,12 @@ Enumerates the device types.
| Name | Value | Description |
| -------------------- | ---- | ---- |
| DEVICE_TYPE_PHONE | 0x00 | Phone. |
| DEVICE_TYPE_TABLET | 0x01 | Tablet. |
| DEVICE_TYPE_CAR | 0x02 | Head unit. |
| DEVICE_TYPE_PC | 0x03 | PC. |
| DEVICE_TYPE_TV | 0x04 | TV. |
| DEVICE_TYPE_WEARABLE | 0x06 | Wearable. |
| DEVICE_TYPE_PHONE | 0x00 | Phone |
| DEVICE_TYPE_TABLET | 0x01 | Tablet |
| DEVICE_TYPE_CAR | 0x02 | Head unit |
| DEVICE_TYPE_PC | 0x03 | PC |
| DEVICE_TYPE_TV | 0x04 | TV |
| DEVICE_TYPE_WEARABLE | 0x06 | Wearable |
## ScreenDensity
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@@ -278,7 +278,7 @@ Defines the capability of accessing application resources.
> **NOTE**
>
> - The methods involved in **ResourceManager** are applicable only to the TypeScript-based declarative development paradigm.
> - The APIs involved in **ResourceManager** are applicable only to the TypeScript-based declarative development paradigm.
>
> - Resource files are defined in the **resources** directory of the project. You can obtain the resource ID using **$r(resource address).id**, for example, **$r('app.string.test').id**.
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@@ -645,7 +645,7 @@ For details about the error codes, see [Resource Manager Error Codes](../errorco
Obtains the singular-plural string corresponding to the specified resource object based on the specified number. This API uses a promise to return the result.
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@@ -1273,10 +1273,10 @@ For details about the error codes, see [Resource Manager Error Codes](../errorco
@@ -2036,7 +2036,7 @@ Obtains the string corresponding to the specified resource ID. This API returns
| Type | Description |
| ------ | ----------- |
| string | String corresponding to the specified resource ID.|
| string | Promise used to return the result.|
For details about the error codes, see [Resource Manager Error Codes](../errorcodes/errorcode-resource-manager.md).
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@@ -2070,7 +2070,7 @@ Obtains the string corresponding to the specified resource ID and formats the st
| Name | Type | Mandatory | Description |
| ----- | ------ | ---- | ----- |
| resId | number | Yes | Resource ID.|
| args | Array<string\|number> | No | Arguments for formatting strings.<br> Supported arguments:<br> -%d, %f, %s, and %%<br> Note: %% is used to translate %.<br>Example: %%d is translated into the %d string.|
| args | Array<string\|number> | No | Arguments for formatting strings.<br> Supported arguments:<br> -%d, %f, %s, and %%<br> Note: **%%** is used to translate **%**.<br>Example: **%%d** is translated into the **%d** string.|
**Return value**
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@@ -2116,7 +2116,7 @@ Obtains the string corresponding to the specified resource object. This API retu
| Type | Description |
| ------ | ---------------- |
| string | String corresponding to the resource object.|
| string | Promise used to return the result.|
For details about the error codes, see [Resource Manager Error Codes](../errorcodes/errorcode-resource-manager.md).
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@@ -2155,7 +2155,7 @@ Obtains the string corresponding to the specified resource object and formats th
| args | Array<string\|number> | No | Arguments for formatting strings.<br> Supported arguments:<br> -%d, %f, %s, and %%<br> Note: %% is used to translate %.<br>Example: %%d is translated into the %d string.|
| args | Array<string\|number> | No | Arguments for formatting strings.<br> Supported arguments:<br> -%d, %f, %s, and %%<br> Note: **%%** is used to translate **%**.<br>Example: **%%d** is translated into the **%d** string.|
**Return value**
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@@ -2206,7 +2206,7 @@ Obtains the string corresponding to the specified resource name. This API return
| Type | Description |
| ------ | ---------- |
| string | String corresponding to the resource name.|
| string | String corresponding to the specified resource name.|
For details about the error codes, see [Resource Manager Error Codes](../errorcodes/errorcode-resource-manager.md).
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@@ -2240,7 +2240,7 @@ Obtains the string corresponding to the specified resource name and formats the
| Name | Type | Mandatory | Description |
| ------- | ------ | ---- | ---- |
| resName | string | Yes | Resource name.|
| args | Array<string \| number> | No | Arguments for formatting strings.<br> Supported arguments:<br> -%d, %f, %s, and %%<br> Note: %% is used to translate %.<br>Example: %%d is translated into the %d string.|
| args | Array<string \| number> | No | Arguments for formatting strings.<br> Supported arguments:<br> -%d, %f, %s, and %%<br> Note: **%%** is used to translate **%**.<br>Example: **%%d** is translated into the **%d** string.|
**Return value**
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@@ -2406,8 +2406,8 @@ Obtains the integer or float value corresponding to the specified resource ID. T
**Return value**
| Type | Description |
| ------ | ---------- |
| number | Integer or float value corresponding to the specified resource ID.|
| ------ | ---------- |
| number | Integer or float value corresponding to the specified resource ID. Wherein, the integer value is the original value, and the float value is the actual pixel value.|
For details about the error codes, see [Resource Manager Error Codes](../errorcodes/errorcode-resource-manager.md).
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@@ -2422,13 +2422,13 @@ For details about the error codes, see [Resource Manager Error Codes](../errorco
@@ -2452,7 +2452,7 @@ Obtains the integer or float value corresponding to the specified resource objec
| Type | Description |
| ------ | --------------- |
| number | Integer or float value corresponding to the specified resource object.|
| number | Integer or float value corresponding to the specified resource object. Wherein, the integer value is the original value, and the float value is the actual pixel value.|
For details about the error codes, see [Resource Manager Error Codes](../errorcodes/errorcode-resource-manager.md).
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@@ -2472,7 +2472,7 @@ For details about the error codes, see [Resource Manager Error Codes](../errorco
id: $r('app.integer.integer_test').id
};
try {
this.context.resourceManager.getNumber(resource);
this.context.resourceManager.getNumber(resource);// integer refers to the original value; float refers to the actual pixel value.
Obtains the singular-plural string corresponding to the specified resource ID based on the specified number. This API uses a promise to return the result.
This API is deprecated since API version 9. You are advised to use [getPluralStringValue](#getpluralstringvalue9) instead.
This API is deprecated since API version 9. You are advised to use [getPluralStringValue](#getpluralstringvalue9).
Obtains the singular-plural string corresponding to the specified resource ID based on the specified number. This API uses an asynchronous callback to return the result.
This API is deprecated since API version 9. You are advised to use [getPluralStringValue](#getpluralstringvalue9-1) instead.
This API is deprecated since API version 9. You are advised to use [getPluralStringValue](#getpluralstringvalue9-1).
The **uiAppearance** module provides basic capabilities for managing the system appearance. It allows for color mode configuration currently, and will introduce more features over time.
