Android 如何创建侦听器来检测前台的活动？
我已经创建了一个创建聊天头的服务（比如Facebook Messenger） 然而，我希望它有一个监听器，总是检查哪个活动或应用程序在前台 这是我的密码-Android 如何创建侦听器来检测前台的活动？,android,service,activity-manager,Android,Service,Activity Manager,我已经创建了一个创建聊天头的服务（比如Facebook Messenger） 然而，我希望它有一个监听器，总是检查哪个活动或应用程序在前台 这是我的密码- public class ChatHeadService extends Service { private WindowManager windowManager; private ImageView chatHead; protected String lastPackageName; @Ov
public class ChatHeadService extends Service {
private WindowManager windowManager;
private ImageView chatHead;
protected String lastPackageName;
@Override
public IBinder onBind(Intent intent) {
return null;
}
@Override
public void onCreate() {
super.onCreate();
ActivityManager am = (ActivityManager) this.getSystemService(ACTIVITY_SERVICE);
String foreground = am.getRunningTasks(1).get(0).topActivity.getPackageName();
if(foreground.equals("com.whatsapp"))
Toast.makeText(getApplicationContext(), foreground, Toast.LENGTH_SHORT).show();
windowManager = (WindowManager) getSystemService(WINDOW_SERVICE);
chatHead = new ImageView(this);
chatHead.setImageResource(R.drawable.view_icon);
final WindowManager.LayoutParams params = new WindowManager.LayoutParams(
WindowManager.LayoutParams.WRAP_CONTENT,
WindowManager.LayoutParams.WRAP_CONTENT,
WindowManager.LayoutParams.TYPE_PHONE,
WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
PixelFormat.TRANSLUCENT);
params.gravity = Gravity.TOP | Gravity.START;
params.x = 0;
params.y = 100;
windowManager.addView(chatHead, params);
}
@Override
public void onDestroy() {
super.onDestroy();
if (chatHead != null) windowManager.removeView(chatHead);
if(lastPackageName!="com.whatsapp") windowManager.removeView(chatHead);
}
}