The EnvironmentCallback module provides capabilities to listen for system environment changes.
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.
[h2]onConfigurationUpdated
onConfigurationUpdated(config: Configuration): void
Called when the system environment changes, after registering a listener for system environment changes via ApplicationContext.on('environment').
The onConfigurationUpdated callback runs in the main thread of the current process. Releasing UI components in this callback may block the main thread tasks. Therefore, you are advised not to release UI components in this callback.
Atomic service API: This API can be used in atomic services since API version 11.
System capability: SystemCapability.Ability.AbilityRuntime.AbilityCore
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| config | Configuration | Yes | Configuration object after the change. |
Example
[h2]onMemoryLevel
onMemoryLevel(level: AbilityConstant.MemoryLevel): void
Called when the system memory changes, after registering a listener for system environment changes via ApplicationContext.on('environment').
The onMemoryLevel callback runs in the main thread of the current process. Releasing UI components in this callback may block the main thread tasks. Therefore, you are advised not to release UI components in this callback.
Atomic service API: This API can be used in atomic services since API version 11.
System capability: SystemCapability.Ability.AbilityRuntime.AbilityCore
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| level | AbilityConstant.MemoryLevel | Yes | Memory level of the entire device. For the corresponding trigger scenarios, see AbilityConstant.MemoryLevel. |
Example
Usage of EnvironmentCallback
Example
import { UIAbility, EnvironmentCallback } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';
let callbackId: number;
export default class MyAbility extends UIAbility {
onCreate() {
console.info('MyAbility onCreate');
let environmentCallback: EnvironmentCallback = {
onConfigurationUpdated(config){
console.info(`onConfigurationUpdated config: ${JSON.stringify(config)}`);
},
onMemoryLevel(level){
console.info(`onMemoryLevel level: ${JSON.stringify(level)}`);
}
};
// 1. Obtain an applicationContext object.
let applicationContext = this.context.getApplicationContext();
try {
// 2. Register the system environment change listener through applicationContext.
callbackId = applicationContext.on('environment', environmentCallback);
} catch (paramError) {
console.error(`error: ${(paramError as BusinessError).code}, ${(paramError as BusinessError).message}`);
}
console.info(`registerEnvironmentCallback number: ${JSON.stringify(callbackId)}`);
}
onDestroy() {
let applicationContext = this.context.getApplicationContext();
try {
applicationContext.off('environment', callbackId, (error, data) => {
if (error && error.code !== 0) {
console.error(`unregisterEnvironmentCallback fail, error: ${JSON.stringify(error)}`);
} else {
console.info(`unregisterEnvironmentCallback success, data: ${JSON.stringify(data)}`);
}
});
} catch (paramError) {
console.error(`error: ${(paramError as BusinessError).code}, ${(paramError as BusinessError).message}`);
}
}
}