@ohos.app.ability.EnvironmentCallback (EnvironmentCallback)

The EnvironmentCallback module provides APIs for the application context to listen for system environment changes.

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

EnvironmentCallback.onConfigurationUpdated

onConfigurationUpdated(config: Configuration): void

Called when the system environment changes.

System capability: SystemCapability.Ability.AbilityRuntime.AbilityCore

Parameters

Example

See Usage of EnvironmentCallback.

EnvironmentCallback.onMemoryLevel

onMemoryLevel(level: AbilityConstant.MemoryLevel): void

Called when the system memory level changes.

System capability: SystemCapability.Ability.AbilityRuntime.AbilityCore

Parameters

Example

See Usage of EnvironmentCallback.

Usage of EnvironmentCallback

Example

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

let callbackId: number;

export default class MyAbility 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: ${JSON.stringify(level)}`);
            }
        };
        // 1. Obtain an applicationContext object.
        let applicationContext = this.context.getApplicationContext();
        // 2. Register a listener for the environment changes through the applicationContext object.
        callbackId = applicationContext.on('environment', environmentCallback);
        console.log(`registerEnvironmentCallback number: ${JSON.stringify(callbackId)}`);
    }

    onDestroy() {
        let applicationContext = this.context.getApplicationContext();
        applicationContext.off('environment', callbackId, (error, data) => {
            if (error && error.code !== 0) {
                console.error(`unregisterEnvironmentCallback fail, error: ${JSON.stringify(error)}`);
            } else {
                console.log(`unregisterEnvironmentCallback success, data: ${JSON.stringify(data)}`);
            }
        });
    }
}