harmony(鸿蒙)ApplicationContext

2022-08-09
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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.

Usage

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

let applicationContext = this.context.getApplicationContext();

ApplicationContext.registerAbilityLifecycleCallback

registerAbilityLifecycleCallback(callback: AbilityLifecycleCallback): number;

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

System capability: SystemCapability.Ability.AbilityRuntime.Core

Parameters

Name	Type	Mandatory	Description
callback	AbilityLifecycleCallback	Yes	Callback used to return the ID of the registered listener.

Return value

Type	Description
number	ID of the registered listener. The ID is incremented by 1 each time the listener is registered. When the ID exceeds 2^63-1, -1 is returned.

Example

import AbilityStage from "@ohos.application.AbilityStage";

var lifecycleId;

export default class MyAbilityStage extends AbilityStage {
    onCreate() {
        console.log("MyAbilityStage onCreate")
        let AbilityLifecycleCallback  =  {
            onAbilityCreate(ability){
                console.log("AbilityLifecycleCallback onAbilityCreate ability:" + JSON.stringify(ability));        
            },
            onAbilityWindowStageCreate(ability){
                console.log("AbilityLifecycleCallback onAbilityWindowStageCreate ability:" + JSON.stringify(ability));           
            },
            onAbilityWindowStageDestroy(ability){
                console.log("AbilityLifecycleCallback onAbilityWindowStageDestroy ability:" + JSON.stringify(ability));
            },
            onAbilityDestroy(ability){
                console.log("AbilityLifecycleCallback onAbilityDestroy ability:" + JSON.stringify(ability));             
            },
            onAbilityForeground(ability){
                console.log("AbilityLifecycleCallback onAbilityForeground ability:" + JSON.stringify(ability));             
            },
            onAbilityBackground(ability){
                console.log("AbilityLifecycleCallback onAbilityBackground ability:" + JSON.stringify(ability));              
            },
            onAbilityContinue(ability){
                console.log("AbilityLifecycleCallback onAbilityContinue ability:" + JSON.stringify(ability));
            }
        }
        // 1. Obtain applicationContext through the context attribute.
        let applicationContext = this.context.getApplicationContext();
        // 2. Use applicationContext to register a listener for the ability lifecycle in the application.
        lifecycleId = applicationContext.registerAbilityLifecycleCallback(AbilityLifecycleCallback);
        console.log("registerAbilityLifecycleCallback number: " + JSON.stringify(lifecycleId));
    }
    onDestroy() {
        let applicationContext = this.context.getApplicationContext();
        applicationContext.unregisterAbilityLifecycleCallback(lifecycleId, (error, data) => {
            console.log("unregisterAbilityLifecycleCallback success, err: " + JSON.stringify(error));
        });
    }
}

ApplicationContext.unregisterAbilityLifecycleCallback

unregisterAbilityLifecycleCallback(callbackId: number, callback: AsyncCallback<void>): void;

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

System capability: SystemCapability.Ability.AbilityRuntime.Core

Parameters

Name	Type	Mandatory	Description
callbackId	number	Yes	ID of the listener to deregister.
callback	AsyncCallback<void>	Yes	Callback used to return the result.

Example

  let applicationContext = this.context.getApplicationContext();
  let lifecycleId = 1;
  console.log("stage applicationContext: " + JSON.stringify(applicationContext));
  applicationContext.unregisterAbilityLifecycleCallback(lifecycleId, (error, data) => {
      console.log("unregisterAbilityLifecycleCallback success, err: " + JSON.stringify(error));
  });

ApplicationContext.registerEnvironmentCallback

registerEnvironmentCallback(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

Name	Type	Mandatory	Description
callback	EnvironmentCallback	Yes	Callback used to return the ID of the registered listener.

Return value

Type	Description
number	ID of the registered listener. The ID is incremented by 1 each time the listener is registered. When the ID exceeds 2^63-1, -1 is returned.

Example

import AbilityStage from "@ohos.application.AbilityStage";

var callbackId;

export default class MyAbilityStage extends AbilityStage {
    onCreate() {
        console.log("MyAbilityStage onCreate")
        globalThis.applicationContext = this.context.getApplicationContext();
        let EnvironmentCallback = {
            onConfigurationUpdated(config){
                console.log("onConfigurationUpdated config:" + JSON.stringify(config));
            },
        }
        // 1. Obtain an applicationContext object.
        let applicationContext = globalThis.applicationContext;
        // 2. Use applicationContext to register a listener for the ability lifecycle in the application.
        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));
        });
    }
}

ApplicationContext.unregisterEnvironmentCallback

unregisterEnvironmentCallback(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

Name	Type	Mandatory	Description
callbackId	number	Yes	ID of the listener to deregister.
callback	AsyncCallback<void>	Yes	Callback used to return the result.

Example

  let applicationContext = this.context.getApplicationContext();
  let callbackId = 1;
  applicationContext.unregisterEnvironmentCallback(callbackId, (error, data) => {
      console.log("unregisterEnvironmentCallback success, err: " + JSON.stringify(error));
  });