# ApplicationContext

ApplicationContext模块提供开发者应用级别的的上下文的能力，包括提供注册及取消注册应用内组件生命周期的监听接口。

> **说明：**
> 
> 本模块首批接口从API version 9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。

## 导入模块

```ts
import common from '@ohos.app.ability.common';
```

## 使用说明

在使用ApplicationContext的功能前，需要通过context的实例获取。

```ts
let applicationContext: common.ApplicationContext = this.context.getApplicationContext();
```

## ApplicationContext.on(type: 'abilityLifecycle', callback: AbilityLifecycleCallback)

on(type: 'abilityLifecycle', callback: AbilityLifecycleCallback): **number**;

注册监听应用内生命周期

**系统能力**：SystemCapability.Ability.AbilityRuntime.Core

**参数：**

| 参数名                   | 类型     | 必填 | 说明                           |
| ------------------------ | -------- | ---- | ------------------------------ |
| type | 'abilityLifecycle' | 是   | 监听事件的类型。 |
| callback | [AbilityLifecycleCallback](js-apis-app-ability-abilityLifecycleCallback.md) | 是   | 回调方法，返回注册监听事件的ID。 |

**返回值：**

| 类型   | 说明                           |
| ------ | ------------------------------ |
| number | 返回的此次注册监听生命周期的ID（每次注册该ID会自增+1，当超过监听上限数量2^63-1时，返回-1）。|

**示例：**

```ts
import UIAbility from '@ohos.app.ability.UIAbility';

let lifecycleId;

export default class EntryAbility extends UIAbility {
    onCreate() {
        console.log('MyAbility onCreate');
        let AbilityLifecycleCallback = {
            onAbilityCreate(ability) {
                console.log('AbilityLifecycleCallback onAbilityCreate ability: ${ability}');
            },
            onWindowStageCreate(ability, windowStage) {
                console.log('AbilityLifecycleCallback onWindowStageCreate ability: ${ability}');
                console.log('AbilityLifecycleCallback onWindowStageCreate windowStage: ${windowStage}');
            },
            onWindowStageActive(ability, windowStage) {
                console.log('AbilityLifecycleCallback onWindowStageActive ability: ${ability}');
                console.log('AbilityLifecycleCallback onWindowStageActive windowStage: ${windowStage}');
            },
            onWindowStageInactive(ability, windowStage) {
                console.log('AbilityLifecycleCallback onWindowStageInactive ability: ${ability}');
                console.log('AbilityLifecycleCallback onWindowStageInactive windowStage: ${windowStage}');
            },
            onWindowStageDestroy(ability, windowStage) {
                console.log('AbilityLifecycleCallback onWindowStageDestroy ability: ${ability}');
                console.log('AbilityLifecycleCallback onWindowStageDestroy windowStage: ${windowStage}');
            },
            onAbilityDestroy(ability) {
                console.log('AbilityLifecycleCallback onAbilityDestroy ability: ${ability}');
            },
            onAbilityForeground(ability) {
                console.log('AbilityLifecycleCallback onAbilityForeground ability: ${ability}');
            },
            onAbilityBackground(ability) {
                console.log('AbilityLifecycleCallback onAbilityBackground ability: ${ability}');
            },
            onAbilityContinue(ability) {
                console.log('AbilityLifecycleCallback onAbilityContinue ability: ${ability}');
            }
        }
        // 1.通过context属性获取applicationContext
        let applicationContext = this.context.getApplicationContext();
        // 2.通过applicationContext注册监听应用内生命周期
        lifecycleId = applicationContext.on('abilityLifecycle', AbilityLifecycleCallback);
        console.log('registerAbilityLifecycleCallback lifecycleId: ${lifecycleId)}');
    }
}
```

## ApplicationContext.off(type: 'abilityLifecycle', callbackId: number, callback: AsyncCallback\<void>)

off(type: 'abilityLifecycle', callbackId: **number**,  callback: AsyncCallback<**void**>): **void**;

取消监听应用内生命周期

**系统能力**：SystemCapability.Ability.AbilityRuntime.Core

**参数：**

| 参数名        | 类型     | 必填 | 说明                       |
| ------------- | -------- | ---- | -------------------------- |
| type | 'abilityLifecycle' | 是   | 取消监听事件的类型。 |
| callbackId    | number   | 是   | 注册监听应用内生命周期的ID。 |
| callback | AsyncCallback\<void> | 是   | 回调方法。                   |

**示例：**

```ts
import UIAbility from '@ohos.app.ability.UIAbility';

let lifecycleId;

export default class EntryAbility extends UIAbility {
    onDestroy() {
        let applicationContext = this.context.getApplicationContext();
        console.log('stage applicationContext: ${applicationContext}');
        applicationContext.off('abilityLifecycle', lifecycleId, (error, data) => {
            if (error) {
                console.error('unregisterAbilityLifecycleCallback fail, err: ${JSON.stringify(error)}');    
            } else {
                console.log('unregisterAbilityLifecycleCallback success, data: ${JSON.stringify(data)}');
            }
        });
    }
}
```

## ApplicationContext.off(type: 'abilityLifecycle', callbackId: number)

off(type: 'abilityLifecycle', callbackId: number): Promise\<void>;

取消监听应用内生命周期

**系统能力**：SystemCapability.Ability.AbilityRuntime.Core

**参数：**

| 参数名        | 类型     | 必填 | 说明                       |
| ------------- | -------- | ---- | -------------------------- |
| type | 'abilityLifecycle' | 是   | 取消监听事件的类型。 |
| callbackId    | number   | 是   | 注册监听应用内生命周期的ID。 |

**示例：**

```ts
import Ability from '@ohos.app.ability.UIAbility';

let lifecycleId;

export default class MyAbility extends Ability {
    onDestroy() {
        let applicationContext = this.context.getApplicationContext();
        console.log('stage applicationContext: ${applicationContext}');
        applicationContext.off('abilityLifecycle', lifecycleId);
    }
}
```

## ApplicationContext.on(type: 'environment', callback: EnvironmentCallback)

on(type: 'environment', callback: EnvironmentCallback): **number**;

注册对系统环境变化的监听。使用callback异步回调。

**系统能力**：SystemCapability.Ability.AbilityRuntime.Core

**参数：**

| 参数名                   | 类型     | 必填 | 说明                           |
| ------------------------ | -------- | ---- | ------------------------------ |
| type | 'environment' | 是   | 监听事件的类型。 |
| callback | [EnvironmentCallback](js-apis-app-ability-environmentCallback.md) | 是   | 回调方法，返回注册监听事件的ID。 |

**返回值：**

| 类型   | 说明                           |
| ------ | ------------------------------ |
| number | 返回的此次注册监听系统环境变化的ID（每次注册该ID会自增+1，当超过监听上限数量2^63-1时，返回-1）。|

**示例：**

```ts
import UIAbility from '@ohos.app.ability.UIAbility';

let callbackId;

export default class EntryAbility extends UIAbility {
    onCreate() {
        console.log('MyAbility onCreate')
        globalThis.applicationContext = this.context.getApplicationContext();
        let environmentCallback = {
            onConfigurationUpdated(config){
                console.log('onConfigurationUpdated config: ${JSON.stringify(config)}');
            },
            onMemoryLevel(level){
                console.log('onMemoryLevel level: ${level}');
            }
        };
        // 1.获取applicationContext
        let applicationContext = globalThis.applicationContext;
        // 2.通过applicationContext注册监听系统环境变化
        callbackId = applicationContext.on('environment', environmentCallback);
        console.log('registerEnvironmentCallback callbackId: ${callbackId}');
    }
}
```

## ApplicationContext.off(type: 'environment', callbackId: number, callback: AsyncCallback\<void>)

off(type: 'environment', callbackId: **number**,  callback: AsyncCallback<**void**>): **void**;

取消对系统环境变化的监听。使用callback异步回调。

**系统能力**：SystemCapability.Ability.AbilityRuntime.Core

**参数：**

| 参数名         | 类型     | 必填 | 说明                       |
| ------------- | -------- | ---- | -------------------------- |
| type | 'environment' | 是   | 取消监听事件的类型。 |
| callbackId    | number   | 是   | 注册监听系统环境变化的ID。   |
| callback | AsyncCallback\<void> | 是   | 回调方法。                  |

**示例：**

```ts
import UIAbility from '@ohos.app.ability.UIAbility';

let callbackId;

export default class EntryAbility extends UIAbility {
    onDestroy() {
        let applicationContext = this.context.getApplicationContext();
        applicationContext.off('environment', callbackId, (error, data) => {
            if (error) {
                console.error('unregisterEnvironmentCallback fail, err: ${JSON.stringify(error)}');
            } else {
                console.log('unregisterEnvironmentCallback success, data: ${JSON.stringify(data)}');
            }
        });
    }
}
```

## ApplicationContext.off(type: 'environment', callbackId: number)

off(type: 'environment', callbackId: **number**,  callback: AsyncCallback<**void**>): **void**;

取消对系统环境变化的监听。使用callback异步回调。

**系统能力**：SystemCapability.Ability.AbilityRuntime.Core

**参数：**

| 参数名         | 类型     | 必填 | 说明                       |
| ------------- | -------- | ---- | -------------------------- |
| type | 'environment' | 是   | 取消监听事件的类型。 |
| callbackId    | number   | 是   | 注册监听系统环境变化的ID。   |

**示例：**

```ts
import Ability from '@ohos.app.ability.UIAbility';

let callbackId;

export default class MyAbility extends Ability {
    onDestroy() {
        let applicationContext = this.context.getApplicationContext();
        applicationContext.off('environment', callbackId);
    }
}
```

## ApplicationContext.on(type: 'applicationStateChange', callback: ApplicationStateChangeCallback)<sup>10+</sup>

on(type: 'applicationStateChange', callback: ApplicationStateChangeCallback): **void**;

注册对当前应用前后台变化的监听。使用callback异步回调。

**系统能力**：SystemCapability.Ability.AbilityRuntime.Core

**参数：**

| 参数名   | 类型                                                         | 必填 | 说明             |
| -------- | ------------------------------------------------------------ | ---- | ---------------- |
| type     | string                                     | 是   | 监听事件类型，必须为'applicationStateChange'。 |
| callback | [ApplicationStateChangeCallback](js-apis-app-ability-applicationStateChangeCallback.md) | 是   | 对于该事件监听的回调方法，可以对应用从后台切换到前台，以及前台切换到后台分别定义回调。       |

**示例：**

```ts
import UIAbility from '@ohos.app.ability.UIAbility';

export default class MyAbility extends UIAbility {
    onCreate() {
        console.log('MyAbility onCreate');
        globalThis.applicationStateChangeCallback = {
            onApplicationForeground() {
                console.info('applicationStateChangeCallback onApplicationForeground');
            },
            onApplicationBackground() {
                console.info('applicationStateChangeCallback onApplicationBackground');
            }
        }

        globalThis.applicationContext = this.context.getApplicationContext();
        // 1.获取applicationContext
        let applicationContext = globalThis.applicationContext;
        // 2.通过applicationContext注册应用前后台状态监听
        applicationContext.on('applicationStateChange', globalThis.ApplicationStateChangeCallback);
        console.log('Resgiter applicationStateChangeCallback');
    }
}
```

## ApplicationContext.off(type: 'applicationStateChange', callback: AsyncCallback\<void>)<sup>10+</sup>

off(type: 'applicationStateChange', callback: AsyncCallback<**void**>): **void**;

取消当前应用指定的前后台变化的监听。

**系统能力**：SystemCapability.Ability.AbilityRuntime.Core

**参数：**

| 参数名   | 类型                     | 必填 | 说明                             |
| -------- | ------------------------ | ---- | -------------------------------- |
| type     | string | 是   | 取消监听事件的类型,必须为'applicationStateChange'。             |
| callback | AsyncCallback\<void>     | 否   | 删除指定callback对应的注册监听。 |

**示例：**

```ts
import UIAbility from '@ohos.app.ability.UIAbility';

export default class EntryAbility extends UIAbility {
    onDestroy() {
        globalThis.applicationStateChangeCallback = {
            onApplicationForeground() {
                console.info('applicationStateChangeCallback onApplicationForeground');
            },
            onApplicationBackground() {
                console.info('applicationStateChangeCallback onApplicationBackground');
            }
        }
        let applicationContext = this.context.getApplicationContext();
        applicationContext.off('applicationStateChange', globalThis.ApplicationStateChangeCallback);
    }
}
```

## ApplicationContext.off(type: 'applicationStateChange')<sup>10+</sup>

off(type: 'applicationStateChange', callback?: ApplicationStateChangeCallback):  **void**;

取消当前应用注册的前后台变化的全部监听。

**系统能力**：SystemCapability.Ability.AbilityRuntime.Core

**参数：**

| 参数名 | 类型          | 必填 | 说明                 |
| ------ | ------------- | ---- | -------------------- |
| type   | string | 是   | 取消监听事件的类型,必须为'applicationStateChange'。 |
| callback | [ApplicationStateChangeCallback](js-apis-app-ability-applicationStateChangeCallback.md) | 否   | 对于该事件监听的回调方法，可以对应用从后台切换到前台，以及前台切换到后台分别定义回调。       |

**示例：**

```ts
import UIAbility from '@ohos.app.ability.UIAbility';

export default class MyAbility extends UIAbility {
    onDestroy() {
        let applicationContext = this.context.getApplicationContext();
        applicationContext.off('applicationStateChange');
    }
}
```

## ApplicationContext.getRunningProcessInformation<sup>9+</sup>

getRunningProcessInformation(): Promise\<Array\<ProcessInformation>>;

获取有关运行进程的信息。

**系统能力**：SystemCapability.Ability.AbilityRuntime.Core

**返回值：**

| 类型 | 说明 |
| -------- | -------- |
| Promise\<Array\<[ProcessInformation](js-apis-inner-application-processInformation.md)>> | 以Promise方式返回接口运行结果及有关运行进程的信息，可进行错误处理或其他自定义处理。 |

**错误码**：

| 错误码ID | 错误信息 |
| ------- | -------- |
| 16000011 | The context does not exist. |
| 16000050 | Internal error. |

以上错误码详细介绍请参考[errcode-ability](../errorcodes/errorcode-ability.md)。

**示例：**

```ts
applicationContext.getRunningProcessInformation().then((data) => {
    console.log('The process running information is: ${JSON.stringify(data)}');
}).catch((error) => {
    console.error('error: ${JSON.stringify(error)}');
});
```

## ApplicationContext.getRunningProcessInformation<sup>9+</sup>

getRunningProcessInformation(callback: AsyncCallback\<Array\<ProcessInformation>>): void;

获取有关运行进程的信息。

**系统能力**：SystemCapability.Ability.AbilityRuntime.Core

**返回值：**

| 类型 | 说明 |
| -------- | -------- |
|AsyncCallback\<Array\<[ProcessInformation](js-apis-inner-application-processInformation.md)>> | 以回调方式返回接口运行结果及有关运行进程的信息，可进行错误处理或其他自定义处理。 |

**错误码**：

| 错误码ID | 错误信息 |
| ------- | -------- |
| 16000011 | The context does not exist. |
| 16000050 | Internal error. |

以上错误码详细介绍请参考[errcode-ability](../errorcodes/errorcode-ability.md)。

**示例：**

```ts
applicationContext.getRunningProcessInformation((err, data) => {
    if (err) {
        console.error('getRunningProcessInformation faile, err: ${JSON.stringify(err)}');
    } else {
        console.log('The process running information is: ${JSON.stringify(data)}');
    }
})
```

## ApplicationContext.killAllProcesses<sup>9+</sup>

killAllProcesses(): Promise\<void\>;

杀死应用所在的进程。

**系统能力**：SystemCapability.Ability.AbilityRuntime.Core

**返回值：**

| 类型 | 说明 |
| -------- | -------- |
| Promise\<void\> | 以Promise方式返回杀死应用所在的进程结果。 |

**错误码**：

| 错误码ID | 错误信息 |
| ------- | -------- |
| 16000011 | The context does not exist. |

以上错误码详细介绍请参考[errcode-ability](../errorcodes/errorcode-ability.md)。

**示例：**

```ts
applicationContext.killAllProcesses();
```

## ApplicationContext.killAllProcesses<sup>9+</sup>

killAllProcesses(callback: AsyncCallback\<void\>);

杀死应用所在的进程。

**系统能力**：SystemCapability.Ability.AbilityRuntime.Core

**返回值：**

| 类型 | 说明 |
| -------- | -------- |
|AsyncCallback\<void\> | 以callback方式返回杀死应用所在的进程结果。 |

**错误码**：

| 错误码ID | 错误信息 |
| ------- | -------- |
| 16000011 | The context does not exist. |

以上错误码详细介绍请参考[errcode-ability](../errorcodes/errorcode-ability.md)。

**示例：**

```ts
applicationContext.killAllProcesses(error => {
    if (error) {
        console.error('killAllProcesses fail, error: ${JSON.stringify(error)}');
    }
});
```