我有一个使用媒体播放器播放音乐的服务。该服务由一个活动启动，如果正在播放音乐并且用户从活动中移开，则服务应继续在后台播放。
将服务在前台运行似乎是有效的（我可以看到通知），但在几乎所有情况下，服务会立即被销毁（系统调用服务的OnDestroy）。
我知道使用startForeground并不意味着服务永远不会被杀死，但它一直很快地被销毁，所以我猜测系统强制杀死服务的资源太少不是原因。
这是我的实现方式： 在活动的OnCreate中，我启动（在后台）并绑定服务。在OnPause中，我将服务置于前台以防止其被销毁：
有什么想法，为什么服务在我离开活动后会被销毁？
这是我的实现方式： 在活动的OnCreate中，我启动（在后台）并绑定服务。在OnPause中，我将服务置于前台以防止其被销毁：
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_play);
// start service
startService(new Intent(this, MyService.class));
// connect to service
bindToService();
...
}
@Override
protected void onDestroy() {
unbindFromService();
super.onDestroy();
};
@Override
protected void onStart() {
super.onStart();
}
@Override
protected void onStop() {
super.onStop();
}
@Override
protected void onPause() {
super.onPause();
if (MediaPlayerService.getInstance().getStatus() == MEDIA_PLAYER_STATUS.Started) {
// current playing something => keep service running
mService.startForeground();
} else {
// stop service
stopService(new Intent(MainActivity.this, MyService.class));
}
}
@Override
protected void onResume() {
super.onResume();
// remove service from foreground
if (mService != null) {
mService.stopForeground();
}
}
void bindToService() {
// Establish a connection with the service. We use an explicit
// class name because we want a specific service implementation that
// we know will be running in our own process (and thus won't be
// supporting component replacement by other applications).
bindService(new Intent(MainActivity.this, MyService.class), mConnection, Context.BIND_AUTO_CREATE);
mIsBound = true;
}
void unbindFromService() {
if (mIsBound) {
// Detach our existing connection.
unbindService(mConnection);
mIsBound = false;
}
}
private final ServiceConnection mConnection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName className, IBinder service) {
// This is called when the connection with the service has been
// established, giving us the service object we can use to
// interact with the service. Because we have bound to a explicit
// service that we know is running in our own process, we can
// cast its IBinder to a concrete class and directly access it.
mService = ((MyService.LocalBinder) service).getService();
mService.registerClient(MainActivity.this);
}
@Override
public void onServiceDisconnected(ComponentName className) {
// This is called when the connection with the service has been
// unexpectedly disconnected -- that is, its process crashed.
// Because it is running in our same process, we should never
// see this happen.
mService = null;
mService.unRegisterClient(MainActivity.this);
}
};
我的Service中的start/stopForeground函数如下：
public void startForeground() {
String songName = "blabla";
// assign the song name to songName
PendingIntent pi = PendingIntent.getActivity(getApplicationContext(), 0,
new Intent(getApplicationContext(), MainActivity.class),
PendingIntent.FLAG_UPDATE_CURRENT);
Notification notification = new Notification();
notification.tickerText = songName;
notification.icon = R.drawable.ic_launcher;
notification.flags |= Notification.FLAG_ONGOING_EVENT;
notification.setLatestEventInfo(getApplicationContext(), "MusicPlayerSample",
"Playing: " + songName, pi);
startForeground(NOTIFICATION_ID, notification);
}
public void stopForeground() {
stopForeground(true);
}
有什么想法，为什么服务在我离开活动后会被销毁？