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
通过使用下面的代码,我能够得到我的应用程序的前台或后台状态。
更多关于它的工作细节,强文本点击这里
import android.content.ComponentCallbacks2;
import android.content.Context;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
private Context context;
private Toast toast;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
context = this;
}
private void showToast(String message) {
//If toast is already showing cancel it
if (toast != null) {
toast.cancel();
}
toast = Toast.makeText(context, message, Toast.LENGTH_SHORT);
toast.show();
}
@Override
protected void onStart() {
super.onStart();
showToast("App In Foreground");
}
@Override
public void onTrimMemory(int level) {
super.onTrimMemory(level);
if (level == ComponentCallbacks2.TRIM_MEMORY_UI_HIDDEN) {
showToast("App In Background");
}
}
}
其他回答
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
我在Github app- prospect -background-listen上创建了一个项目
为应用程序中的所有Activity创建一个BaseActivity。
public class BaseActivity extends Activity {
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
}
public static boolean isAppInFg = false;
public static boolean isScrInFg = false;
public static boolean isChangeScrFg = false;
@Override
protected void onStart() {
if (!isAppInFg) {
isAppInFg = true;
isChangeScrFg = false;
onAppStart();
}
else {
isChangeScrFg = true;
}
isScrInFg = true;
super.onStart();
}
@Override
protected void onStop() {
super.onStop();
if (!isScrInFg || !isChangeScrFg) {
isAppInFg = false;
onAppPause();
}
isScrInFg = false;
}
public void onAppStart() {
// Remove this toast
Toast.makeText(getApplicationContext(), "App in foreground", Toast.LENGTH_LONG).show();
// Your code
}
public void onAppPause() {
// Remove this toast
Toast.makeText(getApplicationContext(), "App in background", Toast.LENGTH_LONG).show();
// Your code
}
}
现在使用这个BaseActivity作为一个超类的所有你的活动像MainActivity扩展BaseActivity和onAppStart将被调用时,你启动你的应用程序和onappause()将被调用时,应用程序从后台从任何屏幕。
由于我没有找到任何方法,它也处理旋转而不检查时间戳,我想我也分享我们现在如何在我们的应用程序中这样做。 对这个答案https://stackoverflow.com/a/42679191/5119746唯一的补充是,我们还考虑了方向。
class MyApplication : Application(), Application.ActivityLifecycleCallbacks {
// Members
private var mAppIsInBackground = false
private var mCurrentOrientation: Int? = null
private var mOrientationWasChanged = false
private var mResumed = 0
private var mPaused = 0
然后,对于回调,我们首先有简历:
// ActivityLifecycleCallbacks
override fun onActivityResumed(activity: Activity?) {
mResumed++
if (mAppIsInBackground) {
// !!! App came from background !!! Insert code
mAppIsInBackground = false
}
mOrientationWasChanged = false
}
和onActivityStopped:
override fun onActivityStopped(activity: Activity?) {
if (mResumed == mPaused && !mOrientationWasChanged) {
// !!! App moved to background !!! Insert code
mAppIsInBackground = true
}
然后,这里是附加的:检查方向变化:
override fun onConfigurationChanged(newConfig: Configuration) {
if (newConfig.orientation != mCurrentOrientation) {
mCurrentOrientation = newConfig.orientation
mOrientationWasChanged = true
}
super.onConfigurationChanged(newConfig)
}
就是这样。希望这能帮助到一些人:)
我知道有点晚了,但我认为所有这些答案都有一些问题,而我这样做了,这是完美的。
创建一个活动生命周期回调,如下所示:
class ActivityLifeCycle implements ActivityLifecycleCallbacks{
@Override
public void onActivityCreated(Activity activity, Bundle savedInstanceState) {
}
@Override
public void onActivityStarted(Activity activity) {
}
Activity lastActivity;
@Override
public void onActivityResumed(Activity activity) {
//if (null == lastActivity || (activity != null && activity == lastActivity)) //use this condition instead if you want to be informed also when app has been killed or started for the first time
if (activity != null && activity == lastActivity)
{
Toast.makeText(MyApp.this, "NOW!", Toast.LENGTH_LONG).show();
}
lastActivity = activity;
}
@Override
public void onActivityPaused(Activity activity) {
}
@Override
public void onActivityStopped(Activity activity) {
}
@Override
public void onActivitySaveInstanceState(Activity activity, Bundle outState) {
}
@Override
public void onActivityDestroyed(Activity activity) {
}
}
然后像下面这样在你的应用类上注册它:
public class MyApp extends Application {
@Override
public void onCreate() {
super.onCreate();
registerActivityLifecycleCallbacks(new ActivityLifeCycle());
}
这是@d60402回答的修改版本:https://stackoverflow.com/a/15573121/4747587
按照上面提到的去做。但是,与其有一个Base Activity,并将其作为每个活动的父活动,并重写onResume()和onPause,不如执行以下操作:
在你的应用程序类中,添加这样一行:
registerActivityLifecycleCallbacks(应用程序。ActivityLifecycleCallbacks回调);
这个回调有所有的活动生命周期方法,你现在可以覆盖onactivityresume()和onActivityPaused()。
看看这个Gist: https://gist.github.com/thsaravana/1fa576b6af9fc8fff20acfb2ac79fa1b
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