# ApplicationStateObserver
定义应用状态监听,可以作为[registerApplicationStateObserver](js-apis-application-appManager.md#appmanagerregisterapplicationstateobserver8)的入参监听当前应用的生命周期变化。
**系统能力**:以下各项对应的系统能力均为SystemCapability.Ability.AbilityRuntime.Core
**系统API**:该接口为系统接口,三方应用不支持调用。
| 名称 | | 类型 | 可读 | 可写 | 说明 |
| ----------------------- | ---------| ---- | ---- | ------------------------- | ------------------------- |
| onForegroundApplicationChanged8+ | [AppStateData](js-apis-inner-application-appStateData.md) | AsyncCallback\ | 是 | 否 | 应用前后台状态发生变化时执行的回调函数。 |
| onAbilityStateChanged8+ | [AbilityStateData](js-apis-inner-application-abilityStateData.md) | AsyncCallback\ | 是 | 否 | ability状态发生变化时执行的回调函数。 |
| onProcessCreated8+ | [ProcessData](js-apis-inner-application-processData.md) | AsyncCallback\ | 是 | 否 | 进程创建时执行的回调函数。 |
| onProcessDied8+ | [ProcessData](js-apis-inner-application-processData.md) | AsyncCallback\ | 是 | 否 | 进程销毁时执行的回调函数。 |
| onProcessStateChanged8+ | [ProcessData](js-apis-inner-application-processData.md) | AsyncCallback\ | 是 | 否 | 进程状态更新时执行的回调函数。 |
**示例:**
```ts
import appManager from '@ohos.app.ability.appManager';
let applicationStateObserver = {
onForegroundApplicationChanged(appStateData) {
console.log('onForegroundApplicationChanged appStateData: ${JSON.stringify(appStateData)}');
},
onAbilityStateChanged(abilityStateData) {
console.log('onAbilityStateChanged onAbilityStateChanged: ${JSON.stringify(abilityStateData)}');
},
onProcessCreated(processData) {
console.log('onProcessCreated onProcessCreated: ${JSON.stringify(processData)}');
},
onProcessDied(processData) {
console.log('onProcessDied onProcessDied: ${JSON.stringify(processData)}');
},
onProcessStateChanged(processData) {
console.log('onProcessStateChanged onProcessStateChanged: ${JSON.stringify(processData)}');
}
};
let observerCode = appManager.registerApplicationStateObserver(applicationStateObserver);
```