Question

当我点击播放按钮播放歌曲并将歌曲mp3与其捆绑在一起并在onStartCommand中接收时，我开始服务。问题是当我启动服务的活动结束时，我的服务再次调用onStartCommand。当它接收该捆绑时它不存在，因为这次活动没有启动它。因此，我在准备媒体播放器时遇到了非法的例外情况。我没有约束我的服务。

为什么在我的活动结束时会调用onStartCommand？

启动服务：

Intent i = new Intent(SongList.this,MyService.class);
i.putExtra("songURL", user.songurlz);
i.putExtra("songNAME", songplay_name);
startService(i);

服务类：

public class MyService extends Service {

    static MediaPlayer mediaPlayer;
    static int pauseplay;
    static NotificationManager notificationManagerPlay;
    static CharSequence tickerText;
    static Notification notification4;//Notification variable(for song playing)
    TelephonyManager telephonyManager;
    PhoneStateListener listener;
    static Notification notification;
    static NotificationManager mNotificationManager;
    String songurl;
    String songname;

    @Override
    public IBinder onBind(Intent intent) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        mediaPlayer = new MediaPlayer();
        pauseplay = 1;
        MainMenu.serviceRunning = 1;
        telephonyManager = (TelephonyManager) getSystemService(
                Context.TELEPHONY_SERVICE);
        // Create a new PhoneStateListener
        listener = new PhoneStateListener() {

            @Override
            public void onCallStateChanged(int state, String incomingNumber) {
                switch (state) {
                case TelephonyManager.CALL_STATE_IDLE:
                    break;
                case TelephonyManager.CALL_STATE_OFFHOOK:
                    break;
                case TelephonyManager.CALL_STATE_RINGING:
                    if (mediaPlayer.isPlaying() == true && mediaPlayer != null){
                        pauseSong();
                    }
                    break;
                }
            }
        };
        // Register the listener wit the telephony manager
        telephonyManager.listen(listener, PhoneStateListener.LISTEN_CALL_STATE);
    }

    public int onStartCommand(Intent intent, int flags, int startId) {
        super.onStartCommand(intent, flags, startId);
        if (intent != null) {
            Bundle bundle = intent.getExtras();
            //Retrieve your data using the name
            songurl = bundle.getString("songURL");
            Bundle bundle2 = intent.getExtras();
            //Retrieve your data using the name
            songname = bundle2.getString("songNAME");
        }
        Toast toast = Toast.makeText(getApplicationContext(), "Now Playing: "
                + songname, Toast.LENGTH_LONG);
        toast.show();
        // configure the intent
        Intent playIntent = new Intent(MyService.this, SongList.class);
        final PendingIntent pendingIntent = PendingIntent.getActivity(
                MyService.this, 0, playIntent, 0);
        notification = new Notification(R.drawable.playicon, "Buffering...",
                System.currentTimeMillis());
        notification.contentView = new RemoteViews(getPackageName(),
                R.layout.custom_notification2);
        notification.contentIntent = pendingIntent;
        if (SongList.bitmap != null) {
            notification.contentView.setImageViewBitmap(R.id.notifimage,
                    SongList.bitmap);
        } else {
            notification.contentView.setImageViewResource(R.id.notifimage,
                    R.drawable.icon);
        }
        notification.contentView
                .setTextViewText(R.id.notiftitle, "Now Playing");
        notification.contentView.setTextViewText(R.id.notiftext, songname);
        notification.flags = notification.flags
                | Notification.FLAG_ONGOING_EVENT;
        mNotificationManager = (NotificationManager) getApplicationContext()
                .getSystemService(Context.NOTIFICATION_SERVICE);
        mNotificationManager.notify(4, notification);
        mediaPlayer.reset();
        mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
        try {
            mediaPlayer.setDataSource(songurl);
        } catch (IllegalArgumentException e) {
            e.printStackTrace();
        } catch (IllegalStateException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        // register an error listener via MediaPlayer's setOnErrorListener
        mediaPlayer.setOnErrorListener(new OnErrorListener() {

            @Override
            public boolean onError(MediaPlayer mp, int what, int extra) {
                Log.e("MEDIAPLAYER ERRORS", "what: " + what + "  extra: "
                        + extra);
                mediaPlayer.reset();
                mNotificationManager.cancel(4);
                return false;
            }
        });
        mediaPlayer.prepareAsync();
        mediaPlayer.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {

            @Override
            public void onPrepared(MediaPlayer mp) {
                mediaPlayer.start();
            }
        });
        mediaPlayer
                .setOnCompletionListener(new MediaPlayer.OnCompletionListener(){

                    public void onCompletion(MediaPlayer mp) {
                        stopSelf();
                    }
                });
        return START_STICKY;
    }

    @Override
    public void onDestroy() {
        MainMenu.serviceRunning = 0;
        mNotificationManager.cancel(4);
    }

    public static void pauseSong() {
        if (mediaPlayer.isPlaying() == true) {
            mediaPlayer.pause();
            mNotificationManager.cancel(4);
            pauseplay = 0;
        }
    }

    public static void playSong() {
        if (pauseplay == 0) {
            mNotificationManager.notify(4, notification);
            mediaPlayer.start();
            pauseplay = 1;
        }
    }
}

Answer 1

为什么在我的活动结束时会调用onStartCommand？

当您的＆＃34;活动结束时，您正在呼叫startService()＆＃34; （无论这意味着什么），或Android由于您使用START_STICKY而因某种原因重新启动您的服务。

就个人而言，对于音乐播放器，我认为START_NOT_STICKY是正确答案。如果您的服务因任何原因而停止，用户应该负责再次启动它。

Answer 2

我知道这个答案可能不再有用，但我遇到了同样的问题，通过查看onStartCommand的{{3}}返回代码的文档，我发现它会解决问题。

编辑：

您的onStartCommand should是这样的：

public int onStartCommand(Intent intent, int flags, int startId)
{
    //the same code
    //......
    //then return the new code which I'm pointing to
    return START_REDELIVER_INTENT;
}

以下是文档对此返回代码的说法：

public static final int START_REDELIVER_INTENT

从onStartCommand(Intent, int, int)返回的常量：如果此服务的进程在启动时被终止（在返回之后） onStartCommand(Intent, int, int)），然后它将被安排重新启动，最后一次交付的Intent再次通过它重新发送给它 onStartCommand(Intent, int, int)。

使用此返回代码将使操作系统每次调用方法onStartCommand时重新发送Intent（无论出于何种原因可能导致此问题）。

一旦活动结束，就会调用onStartCommand服务

2 个答案: