长时任务开发指导 (TaskPool)

此处提供使用TaskPool进行长时任务的开发指导，以定期采集传感器数据为例。

使用TaskPool进行传感器数据监听

导入所需的模块。

import { sensor } from '@kit.SensorServiceKit';
import { taskpool } from '@kit.ArkTS';
import { BusinessError, emitter } from '@kit.BasicServicesKit';

定义长时任务，内部监听sensor数据，并通过emitter注册销毁通知。

@Concurrent
async function sensorListener(): Promise<void> {
  sensor.on(sensor.SensorId.ACCELEROMETER, (data) => {
    emitter.emit({ eventId: 0 }, { data: data });
  }, { interval: 1000000000 });

  emitter.on({ eventId: 1 }, () => {
    sensor.off(sensor.SensorId.ACCELEROMETER)
    emitter.off(1)
  })
}

给应用添加ohos.permission.ACCELEROMETER权限，在module.json5中的"module"字段中添加如下代码示例的"requestPermissions"字段，配置相关权限。
```
"requestPermissions": [
  {
    "name": "ohos.permission.ACCELEROMETER"
  }
]
```

宿主线程定义注册及销毁的行为。

注册：发起长时任务，并通过emitter接收监听数据。
销毁：发送取消传感器监听的事件，并结束长时任务。

import { sensor } from '@kit.SensorServiceKit';
import { taskpool } from '@kit.ArkTS';
import { BusinessError, emitter } from '@kit.BasicServicesKit';

@Concurrent
async function sensorListener(): Promise<void> {
  sensor.on(sensor.SensorId.ACCELEROMETER, (data) => {
    emitter.emit({ eventId: 0 }, { data: data });
  }, { interval: 1000000000 });

  emitter.on({ eventId: 1 }, () => {
    sensor.off(sensor.SensorId.ACCELEROMETER)
    emitter.off(1)
  })
}

@Entry
@Component
struct Index {
  sensorTask?: taskpool.LongTask
  @State addListener: string = 'Add listener';
  @State deleteListener: string = 'Delete listener';

  build() {
    Column() {
      Text(this.addListener)
        .id('Add listener')
        .fontSize(50)
        .fontWeight(FontWeight.Bold)
        .onClick(() => {
          this.sensorTask = new taskpool.LongTask(sensorListener);
          emitter.on({ eventId: 0 }, (data) => {
            // Do something here
            console.info(`Receive ACCELEROMETER data: {${data.data?.x}, ${data.data?.y}, ${data.data?.z}}`);
          });
          taskpool.execute(this.sensorTask).then(() => {
            this.addListener = 'success';
            console.info('Add listener of ACCELEROMETER success');
          }).catch((e: BusinessError) => {
            this.addListener = 'failed';
          })
        })
      Text(this.deleteListener)
        .id('Delete listener')
        .fontSize(50)
        .fontWeight(FontWeight.Bold)
        .onClick(() => {
          emitter.emit({ eventId: 1 });
          emitter.off(0);
          if (this.sensorTask != undefined) {
            taskpool.terminateTask(this.sensorTask);
            this.deleteListener = 'success';
          } else {
            console.error('sensorTask is undefined.');
            this.deleteListener = 'failed';
          }
        })
    }
    .height('100%')
    .width('100%')
  }
}

目录

长时任务开发指导 (TaskPool)

使用TaskPool进行传感器数据监听