# 延迟任务调度开发指导

## 场景介绍

应用要执行对实时性要求不高的任务的时候，比如设备空闲时候做一次数据学习等场景，可以使用延迟调度任务，该机制在满足应用设定条件的时候，会根据系统当前状态，如内存、功耗、热等统一决策调度时间。


## 接口说明
注册相关接口包导入：
```js
import workScheduler from '@ohos.workScheduler';
```

回调相关接口包导入：
```js
import WorkSchedulerExtensionAbility from '@ohos.WorkSchedulerExtensionAbility';
```

### 延迟任务调度

**表1** workScheduler主要接口

接口名                                                    |     接口描述                            
---------------------------------------------------------|-----------------------------------------
startWork(work: WorkInfo): boolean | 延迟调度任务申请 
stopWork(work: WorkInfo, needCancel?: boolean): boolean        | 延迟调度任务取消 
getWorkStatus(workId: number, callback: AsyncCallback\<WorkInfo>): void| 获取延迟调度任务状态（Callback形式） 
getWorkStatus(workId: number): Promise\<WorkInfo> | 获取延迟调度任务状态（Promise形式） 
obtainAllWorks(callback: AsyncCallback\<void>): Array\<WorkInfo>| 获取所有延迟调度任务（Callback形式） 
obtainAllWorks(): Promise<Array\<WorkInfo>>| 获取所有延迟调度任务（Promise形式） 
stopAndClearWorks(): boolean| 停止并清除任务
isLastWorkTimeOut(workId: number, callback: AsyncCallback\<void>): boolean| 获取上次任务是否超时（针对RepeatWork，Callback形式）
isLastWorkTimeOut(workId: number): Promise\<boolean>| 获取上次任务是否超时（针对RepeatWork，Promise形式）

**表2** WorkInfo包含参数

> **说明：** WorkInfo设置参数约束见[延迟任务调度概述](./work-scheduler-overview.md)

参数名| 类型 |描述                       
---------------------------------------------------------|-----------------------------------------|---------------------------------------------------------
workId| number | 延迟任务Id（必填）
bundleName| string | 延迟任务包名（必填）
abilityName| string | 延迟任务回调通知的组件名（必填）
networkType  | [NetworkType](../reference/apis/js-apis-workScheduler.md/#networktype) | 网络类型
isCharging| boolean | 是否充电 
chargerType| [ChargingType](../reference/apis/js-apis-workScheduler.md/#chargingtype) | 充电类型
batteryLevel| number | 电量
batteryStatus| [BatteryStatus](../reference/apis/js-apis-workScheduler.md/#batterystatus) | 电池状态
storageRequest| [StorageRequest](../reference/apis/js-apis-workScheduler.md/#storagerequest) |存储状态
isRepeat| boolean |是否循环任务
repeatCycleTime| number |循环间隔
repeatCount | number|循环次数

**表3** 延迟任务回调接口

接口名                                                    |     接口描述                            
---------------------------------------------------------|-----------------------------------------
onWorkStart(work: WorkInfo): void | 延迟调度任务开始回调
onWorkStop(work: WorkInfo): void | 延迟调度任务结束回调

### 开发步骤

**开发对应的Extension**

    import WorkSchedulerExtensionAbility from '@ohos.WorkSchedulerExtensionAbility';
    
    export default class MyWorkSchedulerExtensionAbility extends WorkSchedulerExtensionAbility {
        onWorkStart(workInfo) {
            console.log('MyWorkSchedulerExtensionAbility onWorkStart' + JSON.stringify(workInfo));
        }
        onWorkStop(workInfo) {
            console.log('MyWorkSchedulerExtensionAbility onWorkStop' + JSON.stringify(workInfo));
        }
    }


**注册延迟任务**



    import workScheduler from '@ohos.workScheduler';
    
    let workInfo = {
        workId: 1,
        batteryLevel:50,
        batteryStatus:workScheduler.BatteryStatus.BATTERY_STATUS_LOW,
        isRepeat: false,
        isPersisted: true,
        bundleName: "com.example.myapplication",
        abilityName: "MyExtension"
    }
    var res = workScheduler.startWork(workInfo);
    console.info("workschedulerLog res:" + res);


**取消延迟任务**


    import workScheduler from '@ohos.workScheduler';
    
    let workInfo = {
        workId: 1,
        batteryLevel:50,
        batteryStatus:workScheduler.BatteryStatus.BATTERY_STATUS_LOW,
        isRepeat: false,
        isPersisted: true,
        bundleName: "com.example.myapplication",
        abilityName: "MyExtension"
    }
    var res = workScheduler.stopWork(workInfo, false);
    console.info("workschedulerLog res:" + res);


**获取指定延迟任务**

1.Callback写法

    workScheduler.getWorkStatus(50, (err, res) => {
      if (err) {
        console.info('workschedulerLog getWorkStatus failed, because:' + err.data);
      } else {
        for (let item in res) {
          console.info('workschedulerLog getWorkStatuscallback success,' + item + ' is:' + res[item]);
        }
      }
    });


2.Promise写法

    workScheduler.getWorkStatus(50).then((res) => {
      for (let item in res) {
        console.info('workschedulerLog getWorkStatus success,' + item + ' is:' + res[item]);
      }
    }).catch((err) => {
      console.info('workschedulerLog getWorkStatus failed, because:' + err.data);
    })


**获取所有延迟任务**

1.Callback写法

    workScheduler.obtainAllWorks((err, res) =>{
      if (err) {
        console.info('workschedulerLog obtainAllWorks failed, because:' + err.data);
      } else {
        console.info('workschedulerLog obtainAllWorks success, data is:' + JSON.stringify(res));
      }
    });

2.Promise写法

    workScheduler.obtainAllWorks().then((res) => {
      console.info('workschedulerLog obtainAllWorks success, data is:' + JSON.stringify(res));
    }).catch((err) => {
      console.info('workschedulerLog obtainAllWorks failed, because:' + err.data);
    })

**停止并清除任务**

    let res = workScheduler.stopAndClearWorks();
    console.info("workschedulerLog res:" + res);

**判断上次执行是否超时**

1.Callback写法

    workScheduler.isLastWorkTimeOut(500, (err, res) =>{
      if (err) {
        console.info('workschedulerLog isLastWorkTimeOut failed, because:' + err.data);
      } else {
        console.info('workschedulerLog isLastWorkTimeOut success, data is:' + res);
      }
    });

2.Promise写法

    workScheduler.isLastWorkTimeOut(500)
      .then(res => {
        console.info('workschedulerLog isLastWorkTimeOut success, data is:' + res);
      })
      .catch(err =>  {
        console.info('workschedulerLog isLastWorkTimeOut failed, because:' + err.data);
      });
    })