Compose - 使用 Lifecycle（生命周期）

原创已于 2025-12-17 19:27:11 修改 · 359 阅读

7 ·

CC 4.0 BY-SA版权

文章标签：

#android

于 2025-11-02 00:55:51 首次发布

Compose 专栏收录该内容

49 篇文章

订阅专栏

官方页面

一、概念

二、收集数据流

val lifecycleOwner = LocalLifecycleOwner.current
//val currentLifecycleState by lifecycleOwner.lifecycle.currentStateFlow.collectAsState()
val currentLifecycleState by lifecycleOwner.lifecycle.currentStateAsState()
when(currentLifecycleState) {
    Lifecycle.State.INITIALIZED -> {}
    Lifecycle.State.CREATED -> {}
    Lifecycle.State.STARTED -> {}
    Lifecycle.State.RESUMED -> {}
    Lifecycle.State.DESTROYED -> {}
}

三、使用可组合项

LifecycleEventEffect 可自由指定需要监听的生命周期。若需要清理资源，可使用 LifecycleStartEffect 和 LifecycleResumeEffect 监听特定生命周期范围，还可以指定 key 来再次触发，必须回调指定方法可用来清理资源。

LifecycleEventEffect

@Composable
public fun LifecycleEventEffect(
event: Lifecycle.Event,
lifecycleOwner: LifecycleOwner = LocalLifecycleOwner.current,
onEvent: () -> Unit
)

在 Activity 处于指定生命周期时开始执行。无法监听 onDestroy()，因为 Compose 在接收到该事件后便会停止重组，永远无法感知到。

LifecycleStartEffect

@Composable
public fun LifecycleStartEffect(
key1: Any?,
lifecycleOwner: LifecycleOwner = LocalLifecycleOwner.current,
effects: LifecycleStartStopEffectScope.() -> LifecycleStopOrDisposeEffectResult
)

在 Activity 处于 start 开始执行，在 stop 或 dispose（可组合项被移除时）时清理资源。

LifecycleResumeEffect

@Composable
public fun LifecycleResumeEffect(
vararg keys: Any?,
lifecycleOwner: LifecycleOwner = LocalLifecycleOwner.current,
effects: LifecycleResumePauseEffectScope.() -> LifecyclePauseOrDisposeEffectResult
)

在 Activity 处于 resume 开始执行，在 pause 或 dispose（可组合项被移除时）时清理资源。

LifecycleEventEffect(Lifecycle.Event.ON_CREATE) {}
LifecycleEventEffect(Lifecycle.Event.ON_START) {}

LifecycleStartEffect(Unit) {
    onStopOrDispose {}
}

LifecycleResumeEffect(Unit) {
    onPauseOrDispose {}
}

四、使用副作用

@Composable
fun Demo() {
    val lifecycleOwner = LocalLifecycleOwner.current
    DisposableEffect(lifecycleOwner) {
        //创建观察者
        val observer = LifecycleEventObserver { _, event ->
            when (event) {
                Lifecycle.Event.ON_CREATE -> {}
                Lifecycle.Event.ON_START -> {}
                Lifecycle.Event.ON_RESUME -> {}
                Lifecycle.Event.ON_PAUSE -> {}
                Lifecycle.Event.ON_STOP -> {}
                Lifecycle.Event.ON_DESTROY -> {}
                else -> {}
            }
        }
        //把观察者加到生命周期里
        lifecycleOwner.lifecycle.addObserver(observer)
        //可组合项被移除时，移除观察者
        onDispose {
            lifecycleOwner.lifecycle.removeObserver(observer)
        }
    }
}