无法修复MediaController.show()异常

Question

我使用MediaPlayer在前台服务中播放音频文件.当用户点击与前台服务关联的通知时,我使用Intent启动一个Activity,如下所示:

Intent audioPlayIntent = new Intent(context, AudioPlayActivity.class);
audioPlayIntent.addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);
audioPlayIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
PendingIntent contentIntent = PendingIntent.getActivity(context, 0, audioPlayIntent, 0);

然后,此Activity绑定到服务以向用户显示MediaController.

这是服务中的绑定代码:

public class AudioPlayerServiceBinder extends Binder{

    public AudioPlayerService getAudioService(){
        return AudioPlayerService.this; //this class is declared in AudioPlayerService.java, so it has access to the Service instance.
    }

}

..并且在Activity中onStart我调用了这个方法:

private void bindAudioService()
    {
        Intent i = new Intent(this, AudioPlayerService.class);
        serviceConnection = new AudioServiceConnection();
        bindService(i, serviceConnection, 0);
    }

我在下面的mediaController.show(5000)行上遇到异常:

private class AudioServiceConnection implements ServiceConnection{

    AudioPlayerServiceBinder audioServiceBinder;
@Override
        public void onServiceConnected(ComponentName name, IBinder serviceBinder)
        {
            serviceConnected = true;
            Log.i(TAG, "Connected to audio player service.");
            audioServiceBinder = ((AudioPlayerServiceBinder) serviceBinder);
            AudioPlayActivity.this.audioService = audioServiceBinder.getAudioService();
            mediaController.show(5000);
        }

唯一的例外是:

android.view.WindowManager$BadTokenException: Unable to add window -- token null is not valid; is your activity running?
at android.view.ViewRoot.setView(ViewRoot.java:527)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:177)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91)
at android.view.Window$LocalWindowManager.addView(Window.java:424)
at android.widget.MediaController.show(MediaController.java:304)
at android.widget.MediaController.show(MediaController.java:249)
at com.myapp.AudioPlayActivity$AudioServiceConnection.onServiceConnected(AudioPlayActivity.java:295)

我可以通过以下方式重新创建相同的异常

1. 单击通知以打开"活动"
2. 按向后关闭活动.
3. 单击通知以打开活动的新版本.

这让我相信mediaController在某种程度上泄漏并试图在原始的Activity实例中展示自己.我找不到任何理由,因为mediaController在Activity的onCreate()中实例化,并且仅与活动本身相关联.(然后,活动处理将命令传递到服务).

Answer 1

show()在上一个活动完成生命周期之前,我认为你过早地打电话.BadTokenException可以通过延迟调用来避免,show()直到调用所有生命周期方法.您可以为此发布延迟的runnable.或者你可以试试,

if (!((Activity)your_context).isFinishing()) {
    mediaController.show(5000);
}

Answer 2

修复了这个问题

我也有同样的问题并通过以下方式修复它,

@Override
public void onAttachedToWindow() {
    super.onAttachedToWindow();
    try{
        mediaController.show(0);
    }catch(Exception e){
        e.printStackTrace();
    }
}

现在它就像一个魅力.