ApplicationContext

The ApplicationContext module provides application-level context. You can use the APIs of this module to register and deregister the ability lifecycle listener in an application.

NOTE

The initial APIs of this module are supported since API version 9. 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 common from '@ohos.app.ability.common';

Usage

Before calling any APIs in ApplicationContext, obtain an ApplicationContext instance through the context instance.

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

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

Registers a listener to monitor the ability lifecycle of the application.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Parameters

Return value

Example

import UIAbility from '@ohos.app.ability.UIAbility';
import AbilityLifecycleCallback from '@ohos.app.ability.AbilityLifecycleCallback';

let lifecycleId: number;

export default class EntryAbility extends UIAbility {
    onCreate() {
        console.log('MyAbility onCreate');
        let AbilityLifecycleCallback: 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. Obtain applicationContext through the context attribute.
        let applicationContext = this.context.getApplicationContext();
        // 2. Use applicationContext.on to subscribe to the 'abilityLifecycle' event.
        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

Deregisters the listener that monitors the ability lifecycle of the application.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Parameters

Example

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

let lifecycleId: number;

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>;

Deregisters the listener that monitors the ability lifecycle of the application.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Parameters

Return value

Example

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

let lifecycleId: number;

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

Registers a listener for system environment changes. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Parameters

Return value

Example

import UIAbility from '@ohos.app.ability.UIAbility';
import EnvironmentCallback from '@ohos.app.ability.EnvironmentCallback';

let callbackId: number;

export default class EntryAbility extends UIAbility {
    onCreate() {
        console.log('MyAbility onCreate')
        let environmentCallback: EnvironmentCallback = {
            onConfigurationUpdated(config){
                console.log(`onConfigurationUpdated config: ${JSON.stringify(config)}`);
            },
            onMemoryLevel(level){
                console.log('onMemoryLevel level: ${level}');
            }
        };
        // 1. Obtain an applicationContext object.
        let applicationContext = this.context.getApplicationContext();
        // 2. Use applicationContext.on() to subscribe to the 'environment' event.
        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

Deregisters the listener for system environment changes. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Parameters

Example

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

let callbackId: number;

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): Promise<void>

Deregisters the listener for system environment changes.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Parameters

Return value

Example

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

let callbackId: number;

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

ApplicationContext.on(type: 'applicationStateChange', callback: ApplicationStateChangeCallback)¹⁰⁺

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

Registers a listener for application foreground/background state changes. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Parameters

Example

import UIAbility from '@ohos.app.ability.UIAbility';
import ApplicationStateChangeCallback from '@ohos.app.ability.ApplicationStateChangeCallback';

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

        // 1. Obtain an applicationContext object.
        let applicationContext = this.context.getApplicationContext();
        // 2. Use applicationContext.on() to subscribe to the 'applicationStateChange' event.
        applicationContext.on('applicationStateChange', applicationStateChangeCallback);
        console.log('Resgiter applicationStateChangeCallback');
    }
}

ApplicationContext.off(type: 'applicationStateChange')¹⁰⁺

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

Deregisters all the listeners for application foreground/background state changes.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Parameters

Example

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

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

ApplicationContext.getRunningProcessInformation

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

Obtains information about the running processes. This API uses a promise to return the result.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Return value

Error codes

For details about the error codes, see Ability Error Codes.

Example

import UIAbility from '@ohos.app.ability.UIAbility';
import { BusinessError } from '@ohos.base';

export default class MyAbility extends UIAbility {
    onForeground() {
        let applicationContext = this.context.getApplicationContext();
        applicationContext.getRunningProcessInformation().then((data) => {
            console.log(`The process running information is: ${JSON.stringify(data)}`);
        }).catch((error: BusinessError) => {
            console.error(`error: ${JSON.stringify(error)}`);
        });
    }
}

ApplicationContext.getRunningProcessInformation

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

Obtains information about the running processes. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Parameters

Error codes

For details about the error codes, see Ability Error Codes.

Example

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

export default class MyAbility extends UIAbility {
    onForeground() {
        let applicationContext = this.context.getApplicationContext();
        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

killAllProcesses(): Promise<void>;

Kills all the processes where the application is located. This API uses a promise to return the result.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Return value

Error codes

For details about the error codes, see Ability Error Codes.

Example

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

export default class MyAbility extends UIAbility {
    onBackground() {
        let applicationContext = this.context.getApplicationContext();
        applicationContext.killAllProcesses();
    }
}

ApplicationContext.killAllProcesses

killAllProcesses(callback: AsyncCallback<void>): void

Kills all the processes where the application is located. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Parameters

Error codes

For details about the error codes, see Ability Error Codes.

Example

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

export default class MyAbility extends UIAbility {
    onBackground() {
        let applicationContext = this.context.getApplicationContext();
        applicationContext.killAllProcesses(error => {
            if (error) {
                console.error(`killAllProcesses fail, error: ${JSON.stringify(error)}`);
            }
        });
    }
}