harmony 鸿蒙@ohos.app.ability.DriverExtensionAbility (DriverExtensionAbility)

2023-10-30
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@ohos.app.ability.DriverExtensionAbility (DriverExtensionAbility)

The DriverExtensionAbility module provides the ExtensionAbility related to drivers. It provides lifecycle callbacks to be invoked when a driver is created, destroyed, connected, or disconnected.

NOTE

The initial APIs of this module are supported since API version 10. Newly added APIs will be marked with a superscript to indicate their earliest API version.

The APIs of this module can be used only in the stage model.

Modules to Import

import DriverExtension from '@ohos.app.ability.DriverExtensionAbility';

Required Permissions

None.

Attributes

System capability: SystemCapability.Driver.ExternalDevice

Name	Type	Readable	Writable	Description
context	DriverExtensionContext	Yes	No	Context of the DriverExtension. This context is inherited from ExtensionContext.

DriverExtensionAbility.onInit

onInit(want: Want): void;

Called when a DriverExtensionAbility is created to initialize the service logic.

System capability: SystemCapability.Driver.ExternalDevice

Parameters

Name	Type	Mandatory	Description
want	Want	Yes	Want information related to this DriverExtensionAbility, including the ability name and bundle name.

Example

  import DriverExtension from '@ohos.app.ability.DriverExtensionAbility';
  import Want from '@ohos.app.ability.Want';
  class DriverExt extends DriverExtension {
    onInit(want : Want) {
      console.log('onInit, want: ${want.abilityName}');
    }
  }

DriverExtensionAbility.onRelease

onRelease(): void;

Called when this DriverExtensionAbility is destroyed to clear resources.

System capability: SystemCapability.Driver.ExternalDevice

Example

  class DriverExt extends DriverExtension {
    onRelease() {
      console.log('onRelease');
    }
  }

DriverExtensionAbility.onConnect

onConnect(want: Want): rpc.RemoteObject|Promise;

Called following onCreate() when a DriverExtensionAbility is started by calling connectAbility(). A RemoteObject object is returned for communication between the server and client.

System capability: SystemCapability.Driver.ExternalDevice

Parameters

Name	Type	Mandatory	Description
want	Want	Yes	Want information related to this DriverExtensionAbility, including the ability name and bundle name.

Return value

Type	Description
rpc.RemoteObject	A RemoteObject object used for communication between the server and client.

Example

  import DriverExtension from '@ohos.app.ability.DriverExtensionAbility';
  import rpc from '@ohos.rpc';
  import Want from '@ohos.app.ability.Want';
  class StubTest extends rpc.RemoteObject{
      constructor(des : string) {
          super(des);
      }
      onRemoteMessageRequest(code : number, data : rpc.MessageSequence, reply : rpc.MessageSequence, option : rpc.MessageOption) {
        // This interface must be overridden.
        return true;
      }
  }
  class DriverExt extends DriverExtension {
    onConnect(want : Want) {
      console.log('onConnect , want: ${want.abilityName}');
      return new StubTest('test');
    }
  }

If the returned RemoteObject object depends on an asynchronous API, you can use the asynchronous lifecycle.

import DriverExtension from '@ohos.app.ability.DriverExtensionAbility';
import rpc from '@ohos.rpc';
import Want from '@ohos.app.ability.Want';
class StubTest extends rpc.RemoteObject{
    constructor(des : string) {
        super(des);
    }
    onRemoteMessageRequest(code : number, data : rpc.MessageSequence, reply : rpc.MessageSequence, option : rpc.MessageOption) {
      // This interface must be overridden.
      return true;
    }
}
async function getDescriptor() {
    // Call the asynchronous function.
    return "asyncTest"
}
class DriverExt extends DriverExtension {
  async onConnect(want : Want) {
    console.log(`onConnect , want: ${want.abilityName}`);
    let descriptor = await getDescriptor();
    return new StubTest(descriptor);
  }
}

DriverExtensionAbility.onDisconnect

onDisconnect(want: Want): void|Promise<void>;

Called when a client is disconnected from this DriverExtensionAbility.

System capability: SystemCapability.Driver.ExternalDevice

Parameters

Name	Type	Mandatory	Description
want	Want	Yes	Want information related to this DriverExtensionAbility, including the ability name and bundle name.

Example

  import DriverExtension from '@ohos.app.ability.DriverExtensionAbility';
  import Want from '@ohos.app.ability.Want';
  class DriverExt extends DriverExtension {
    onDisconnect(want : Want) {
      console.log('onDisconnect, want: ${want.abilityName}');
    }
  }

After the onDisconnect lifecycle callback is executed, the application may exit. As a result, the asynchronous function in onDisconnect may fail to be executed correctly, for example, asynchronously writing data to the database. The asynchronous lifecycle can be used to ensure that the subsequent lifecycle continues after the asynchronous onDisconnect is complete.

import DriverExtension from '@ohos.app.ability.DriverExtensionAbility';
import Want from '@ohos.app.ability.Want';
class DriverExt extends DriverExtension {
  async onDisconnect(want : Want) {
    console.log('onDisconnect, want: ${want.abilityName}');
    // Call the asynchronous function.
  }
}

DriverExtensionAbility.onDump

onDump(params: Array<string>): Array<string>;

Dumps client information.

System capability: SystemCapability.Driver.ExternalDevice

Parameters

Name	Type	Mandatory	Description
params	Array<string>	Yes	Parameters in the form of a command.

Example

  class DriverExt extends DriverExtension {
      onDump(params : Array<string>) {
          console.log(`dump, params: ${JSON.stringify(params)}`);
          return ['params'];
      }
  }