xref: /docs/zh-cn/application-dev/reference/apis-backgroundtasks-kit/js-apis-inner-application-WorkSchedulerExtensionContext-sys.md

# WorkSchedulerExtensionContext (系统接口)

WorkSchedulerExtensionContext是WorkSchedulerExtensionAbility的上下文环境，继承自[ExtensionContext](../apis-ability-kit/js-apis-inner-application-extensionContext.md)。

WorkSchedulerExtensionContext可直接作为WorkSchedulerExtension的上下文环境，提供允许访问特定于WorkSchedulerExtensionAbility的资源的能力。

> **说明：**
> 
> 本模块首批接口从API version 14开始支持。后续版本的新增接口，采用上角标单独标记接口的起始版本。
>
> 本模块接口仅可在Stage模型下使用。
>
> 本模块为系统接口。

## 使用说明

通过WorkSchedulerExtensionAbility子类实例来获取。

```ts
import { WorkSchedulerExtensionAbility, workScheduler } from from '@kit.BackgroundTasksKit';

class MyWorkSchedulerExtensionAbility extends WorkSchedulerExtensionAbility {
    onWorkStart(workInfo: workScheduler.WorkInfo) {
        let WorkSchedulerExtensionContext = this.context; // 获取WorkSchedulerExtensionContext
    }
}
```

## WorkSchedulerExtensionContext.startServiceExtensionAbility

startServiceExtensionAbility(want: Want): Promise\<void>

启动ServiceExtensionAbility，使用Promise异步回调。

**系统能力**：SystemCapability.ResourceSchedule.WorkScheduler

**参数：**

| 参数名 | 类型 | 必填 | 说明 |
| -------- | -------- | -------- | -------- |
| want | [Want](../apis-ability-kit/js-apis-app-ability-want.md) | 是 | 启动Ability的want信息。 |

**返回值：**

| 类型 | 说明 |
| -------- | -------- |
| Promise&lt;void&gt; | 无返回结果的Promise对象。|

**错误码：**

以下错误码详细介绍请参考[通用错误码](../errorcode-universal.md)和[元能力子系统错误码](../apis-ability-kit/errorcode-ability.md)。

| 错误码ID | 错误信息 |
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 202 | The application is not system-app, can not use system-api. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000002 | Incorrect ability type. |
| 16000004 | Can not start invisible component. |
| 16000005 | The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000008 | The crowdtesting application expires. |
| 16000011 | The context does not exist.        |
| 16000012 | The application is controlled.        |
| 16000013 | The application is controlled by EDM.       |
| 16000019 | Can not match any component. |
| 16000050 | Internal error. |
| 16200001 | The caller has been released. |

**示例：**

```ts
import { WorkSchedulerExtensionAbility, workScheduler } from '@kit.BackgroundTasksKit';
import { Want } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

let want : Want = {
  bundleName: 'com.example.workscheduler',
  abilityName: 'ServiceExtAbility'
}

export default class MyWorkSchedulerExtensionAbility extends WorkSchedulerExtensionAbility {
  onWorkStart(workInfo: workScheduler.WorkInfo) {
    console.info(`onWorkStart, workInfo = ${JSON.stringify(workInfo)}`);
      // 拉起对应的service
      this.context.startServiceExtensionAbility(want).then(() => {
        console.info('succeeded in starting ServiceExtensionAbility.');
      }).catch ((err: BusinessError) => {
        console.error('failed to start ServiceExtensionAbility.');
      });
  }

  onWorkStop(workInfo: workScheduler.WorkInfo) {
    console.info(`onWorkStop, workInfo is ${JSON.stringify(workInfo)}`);
  }
}
```

## WorkSchedulerExtensionContext.stopServiceExtensionAbility

stopServiceExtensionAbility(want: Want): Promise\<void>

停止ServiceExtensionAbility，使用Promise异步回调。

**系统能力**：SystemCapability.ResourceSchedule.WorkScheduler

**参数：**

| 参数名 | 类型 | 必填 | 说明 |
| -------- | -------- | -------- | -------- |
| want | [Want](../apis-ability-kit/js-apis-app-ability-want.md) | 是 | 停止Ability的want信息。 |

**返回值：**

| 类型 | 说明 |
| -------- | -------- |
| Promise&lt;void&gt; | 无返回结果的Promise对象。|

**错误码：**

以下错误码详细介绍请参考[通用错误码](../errorcode-universal.md)和[元能力子系统错误码](../apis-ability-kit/errorcode-ability.md)。

| 错误码ID | 错误信息 |
| ------- | -------- |
| 201 | The application does not have permission to call the interface. |
| 202 | The application is not system-app, can not use system-api. |
| 401 | Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed. |
| 16000001 | The specified ability does not exist. |
| 16000002 | Incorrect ability type. |
| 16000004 | Can not start invisible component. |
| 16000005 | The specified process does not have the permission. |
| 16000006 | Cross-user operations are not allowed. |
| 16000011 | The context does not exist.        |
| 16000050 | Internal error. |
| 16200001 | The caller has been released. |

**示例：**

```ts
import { WorkSchedulerExtensionAbility, workScheduler } from '@kit.BackgroundTasksKit';
import { Want } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

let want : Want = {
  bundleName: 'com.example.workscheduler',
  abilityName: 'ServiceExtAbility'
}

export default class MyWorkSchedulerExtensionAbility extends WorkSchedulerExtensionAbility {
  onWorkStart(workInfo: workScheduler.WorkInfo) {
    console.info(`onWorkStart, workInfo = ${JSON.stringify(workInfo)}`);
  }

  onWorkStop(workInfo: workScheduler.WorkInfo) {
    console.info(`onWorkStop, workInfo is ${JSON.stringify(workInfo)}`);
      // 停止对应的service
      this.context.stopServiceExtensionAbility(want).then(() => {
        console.info('succeeded in stopping ServiceExtensionAbility.');
      }).catch ((err: BusinessError) => {
        console.error('failed to stop ServiceExtensionAbility.');
      });
  }
}
```