harmony 鸿蒙@ohos.application.EnvironmentCallback (EnvironmentCallback)

2022-08-09
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@ohos.application.EnvironmentCallback (EnvironmentCallback)

The EnvironmentCallback module provides APIs, such as onConfigurationUpdated and onMemoryLevel, for the application context to listen for system environment changes.

NOTE

The APIs of this module are supported since API version 9 and are deprecated in versions later than API version 9. You are advised to use @ohos.app.ability.EnvironmentCallback instead. 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.application.EnvironmentCallback";

EnvironmentCallback.onConfigurationUpdated

onConfigurationUpdated(config: Configuration): void;

Called when the system environment changes.

System capability: SystemCapability.Ability.AbilityRuntime.AbilityCore

Parameters

Name	Type	Mandatory	Description
config	Configuration	Yes	Configuration object after the change.

EnvironmentCallback.onMemoryLevel

onMemoryLevel(level: number): void;

Called when the system memory level changes.

System capability: SystemCapability.Ability.AbilityRuntime.AbilityCore

Parameters

Name	Type	Mandatory	Description
level	MemoryLevel	Yes	New memory level.

Example

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

var 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. Obtain an applicationContext object.
        let applicationContext = globalThis.applicationContext;
        // 2. Register a listener for the environment changes through the applicationContext object.
        callbackId = applicationContext.registerEnvironmentCallback(EnvironmentCallback);
        console.log("registerEnvironmentCallback number: " + JSON.stringify(callbackId));
    }
    onDestroy() {
        let applicationContext = globalThis.applicationContext;
        applicationContext.unregisterEnvironmentCallback(callbackId, (error, data) => {
            console.log("unregisterEnvironmentCallback success, err: " + JSON.stringify(error));
        });
    }
}