android - 如何修复NoClassDefFoundError : android.media.session.MediaSessionManager

我制作了一个可以在api 20+中完美运行的应用程序，但对于Android 4.4及以下版本，它因错误NoClassDefFoundError: android.media.session.MediaSessionManager而崩溃，这是我在开发人员控制台中获得的堆栈跟踪。

java.lang.NoClassDefFoundError: android.media.session.MediaSessionManager
at beatbox.neelay.beatbox.MediaService.initMediaSession(MediaService.java:634)
at beatbox.neelay.beatbox.MediaService.onStartCommand(MediaService.java:170)
at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2913)
at android.app.ActivityThread.access$2100(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1442)
at android.os.Handler.dispatchMessage(Handler.java:110)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:5339)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:828)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:644)
at dalvik.system.NativeStart.main(Native Method)

我只能从此理解的是initMediaSession方法中的错误。这是我的initMediaSession方法

private void initMediaSession() throws RemoteException {
    if (mediaSessionManager != null) return; //mediaSessionManager exists

    mediaSessionManager = (MediaSessionManager) getSystemService(Context.MEDIA_SESSION_SERVICE);
    // Create a new MediaSession
    mediaSession = new MediaSessionCompat(getApplicationContext(), "AudioPlayer");
    //Get MediaSessions transport controls
    transportControls = mediaSession.getController().getTransportControls();
    //set MediaSession -> ready to receive media commands
    mediaSession.setActive(true);
    //indicate that the MediaSession handles transport control commands
    // through its MediaSessionCompat.Callback.
    mediaSession.setFlags(MediaSessionCompat.FLAG_HANDLES_TRANSPORT_CONTROLS);

    //Set mediaSession's MetaData
    updateMetaData();
    // passing the data


    // Attach Callback to receive MediaSession updates
    mediaSession.setCallback(new MediaSessionCompat.Callback() {
        // Implement callbacks
        @Override
        public void onPlay() {
            super.onPlay();
            messagesent();
            a = false;
            resumeMedia();
            buildNotification(PlaybackStatus.PLAYING);
        }

        @Override
        public void onPause() {
            super.onPause();
            messagesent();
            a = true;
            pauseMedia();
            buildNotification(PlaybackStatus.PAUSED);
        }

        @Override
        public void onSkipToNext() {
            super.onSkipToNext();

            skipToNext();
            updateMetaData();
            buildNotification(PlaybackStatus.PLAYING);
        }

        @Override
        public void onSkipToPrevious() {
            super.onSkipToPrevious();

            skipToPrevious();
            updateMetaData();
            buildNotification(PlaybackStatus.PLAYING);
        }

        @Override
        public void onStop() {
            super.onStop();
            removeNotification();
            //Stop the service
            pauseMedia();
            messagesent();
            stopSelf();
        }

        @Override
        public void onSeekTo(long position) {
            super.onSeekTo(position);
        }
    });
}

我不明白为什么它会在4.4及以下版本的设备上崩溃，我怎么能解决这个问题。我用google搜索并得到了this，但是这篇文章没有告诉你如何解决这个问题。

最佳答案

MediaSessionManager仅在api 21(5.0)中添加

如果绝对需要使用它，则可以将min sdk设置为21或使用以下方法检查内部版本号:

android.os.Build.VERSION.SDK