我试图写一个应用程序,做一些具体的时候,它被带回前台后一段时间。是否有一种方法可以检测应用程序是被发送到后台还是被带到前台?
当前回答
2021年11月更新
实际设置如下
class App : Application() {
override fun onCreate() {
super.onCreate()
ProcessLifecycleOwner.get().lifecycle.addObserver(AppLifecycleListener())
}
}
class AppLifecycleListener : DefaultLifecycleObserver {
override fun onStart(owner: LifecycleOwner) { // app moved to foreground
}
override fun onStop(owner: LifecycleOwner) { // app moved to background
}
}
依赖关系
implementation "androidx.lifecycle:lifecycle-process:$lifecycle_version"
implementation "androidx.lifecycle:lifecycle-common:$lifecycle_version"
原来的答案
ProcessLifecycleOwner似乎也是一个很有前途的解决方案。
ProcessLifecycleOwner将分派ON_START, ON_RESUME事件,当第一个活动通过这些事件时。ON_PAUSE, ON_STOP,事件将在最后一个活动通过它们后延迟分派。这个延迟足够长,可以保证ProcessLifecycleOwner在由于配置更改而销毁和重新创建活动时不会发送任何事件。
实现可以简单到
class AppLifecycleListener : LifecycleObserver {
@OnLifecycleEvent(Lifecycle.Event.ON_START)
fun onMoveToForeground() { // app moved to foreground
}
@OnLifecycleEvent(Lifecycle.Event.ON_STOP)
fun onMoveToBackground() { // app moved to background
}
}
// register observer
ProcessLifecycleOwner.get().lifecycle.addObserver(AppLifecycleListener())
根据源代码,当前延迟值为700ms。
使用此特性还需要依赖项:
implementation "androidx.lifecycle:lifecycle-extensions:$lifecycleVersion"
其他回答
你可以使用:
onRestart ()
重新开始和重新开始的区别。
2021年11月更新
实际设置如下
class App : Application() {
override fun onCreate() {
super.onCreate()
ProcessLifecycleOwner.get().lifecycle.addObserver(AppLifecycleListener())
}
}
class AppLifecycleListener : DefaultLifecycleObserver {
override fun onStart(owner: LifecycleOwner) { // app moved to foreground
}
override fun onStop(owner: LifecycleOwner) { // app moved to background
}
}
依赖关系
implementation "androidx.lifecycle:lifecycle-process:$lifecycle_version"
implementation "androidx.lifecycle:lifecycle-common:$lifecycle_version"
原来的答案
ProcessLifecycleOwner似乎也是一个很有前途的解决方案。
ProcessLifecycleOwner将分派ON_START, ON_RESUME事件,当第一个活动通过这些事件时。ON_PAUSE, ON_STOP,事件将在最后一个活动通过它们后延迟分派。这个延迟足够长,可以保证ProcessLifecycleOwner在由于配置更改而销毁和重新创建活动时不会发送任何事件。
实现可以简单到
class AppLifecycleListener : LifecycleObserver {
@OnLifecycleEvent(Lifecycle.Event.ON_START)
fun onMoveToForeground() { // app moved to foreground
}
@OnLifecycleEvent(Lifecycle.Event.ON_STOP)
fun onMoveToBackground() { // app moved to background
}
}
// register observer
ProcessLifecycleOwner.get().lifecycle.addObserver(AppLifecycleListener())
根据源代码,当前延迟值为700ms。
使用此特性还需要依赖项:
implementation "androidx.lifecycle:lifecycle-extensions:$lifecycleVersion"
使用ProcessLifecycleOwner在Activity(或任何类)中从后台到前台检测app的示例。 当应用程序启动时,我缓存启动时间,然后在每个活动中,我将检查应用程序时间,以知道活动是否在第一时间启动或从后台启动
class MyApplication : Application(), LifecycleObserver {
var appStartBeginTime: Long? = null
override fun onCreate() {
super.onCreate()
ProcessLifecycleOwner.get().lifecycle.addObserver(this);
}
@OnLifecycleEvent(Lifecycle.Event.ON_START)
fun onMoveToForeground() {
Log.i("TAG", "onMoveToForeground")
appStartBeginTime = System.currentTimeMillis()
}
}
LoginActivity
class LoginActivity : AppCompatActivity() {
var localAppStartBeginTime: Long? = null
...
// Detect in onResume() instead of onStart because
// onMoveToForeground() in MyApplication will fired before onStart
override fun onResume() {
super.onResume()
if (isOpenedFirstTimeOrFromBackground()) {
Log.i("TAG", "open first time or from background")
// do something: eg, call API
} else {
Log.i("TAG", "on in another time")
}
}
private fun isOpenedFirstTimeOrFromBackground(): Boolean {
val globalStartBeginTime = (application as MyApplication).appStartBeginTime
if (localAppStartBeginTime != globalStartBeginTime) {
localAppStartBeginTime = globalStartBeginTime
return true
}
return false
}
}
安卓清单
<manifest ...>
<application
android:name=".MyApplication"
...>
</application>
</manifest>
演示 https://github.com/PhanVanLinh/AndroidDetectAppFromBackgroundToForeground
lifecycle包提供了类和接口,让您可以构建生命周期感知的组件
您的应用程序应该实现LifecycleObserver接口:
public class MyApplication extends Application implements LifecycleObserver {
@Override
public void onCreate() {
super.onCreate();
ProcessLifecycleOwner.get().getLifecycle().addObserver(this);
}
@OnLifecycleEvent(Lifecycle.Event.ON_STOP)
private void onAppBackgrounded() {
Log.d("MyApp", "App in background");
}
@OnLifecycleEvent(Lifecycle.Event.ON_START)
private void onAppForegrounded() {
Log.d("MyApp", "App in foreground");
}
}
为此,您需要将此依赖项添加到构建中。gradle文件:
dependencies {
implementation "android.arch.lifecycle:extensions:1.1.1"
}
正如谷歌所建议的,你应该最小化在activity的生命周期方法中执行的代码:
一种常见的模式是实现依赖的操作 活动和片段的生命周期方法中的组件。 然而,这种模式会导致代码组织不佳,并且导致 错误的扩散。通过使用生命周期感知组件,您 是否可以将依赖组件的代码移出生命周期方法 以及组件本身。
你可以在这里阅读更多: https://developer.android.com/topic/libraries/architecture/lifecycle
LifecycleObserver已弃用。使用DefaultLifecycleObserver代替:
public class YourApplication extends Application implements DefaultLifecycleObserver {
@Override
public void onCreate() {
super.onCreate();
ProcessLifecycleOwner.get().getLifecycle().addObserver(this);
}
@Override
public void onStart(@NonNull LifecycleOwner owner) {
DefaultLifecycleObserver.super.onStart(owner);
}
@Override
public void onResume(@NonNull LifecycleOwner owner) {
DefaultLifecycleObserver.super.onResume(owner);
}
@Override
public void onPause(@NonNull LifecycleOwner owner) {
DefaultLifecycleObserver.super.onPause(owner);
}
@Override
public void onStop(@NonNull LifecycleOwner owner) {
DefaultLifecycleObserver.super.onStop(owner);
}
@Override
public void onDestroy(@NonNull LifecycleOwner owner) {
DefaultLifecycleObserver.super.onDestroy(owner);
}
}
依赖关系:
implementation 'androidx.lifecycle:lifecycle-common:2.5.1'
implementation 'androidx.lifecycle:lifecycle-process:2.5.1'
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