harmony 鸿蒙@ohos.app.ability.EnvironmentCallback (EnvironmentCallback)
@ohos.app.ability.EnvironmentCallback (EnvironmentCallback)
The EnvironmentCallback module provides the onConfigurationUpdated API 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
Name | Type | Mandatory | Description |
---|---|---|---|
config | Configuration | Yes | Configuration object after the change. |
EnvironmentCallback.onMemoryLevel
onMemoryLevel(level: AbilityConstant.MemoryLevel): void;
Called when the system memory level changes.
System capability: SystemCapability.Ability.AbilityRuntime.AbilityCore
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
level | AbilityConstant.MemoryLevel | Yes | Memory level that indicates the memory usage status. When the specified memory level is reached, a callback will be invoked and the system will start adjustment. |
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('environmentEvent', 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)}`);
}
});
}
}
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