调用reset（） - Android时，MediaPlayer会导致IllegalStateException

Question

我试图创建一个简单的Android应用程序，它预先 MediaPlayer2 ，而 MediaPlayer1 正在播放内容。我使用了两个VideoView实例。目标是在两种不同内容之间切换时最小化黑屏。

第一个视频在 MediaPlayer1 中效果很好。但是，完成后， MediaPlayer2 开始呈现。然后，在MediaPlayer2的onInfoListener（）内，MediaPlayer1的reset（）在调用时抛出IllegalStateException。我在此处查看了Google文档中的状态图：http://developer.android.com/reference/android/media/MediaPlayer.html。

基于文档，MediaPlayer似乎处于有效状态，允许它调用reset（）。知道问题在这里吗？

代码

public class PrebufferingActivity extends Activity {
private VideoView player1;
private VideoView player2;

private MediaPlayer mediaPlayer1;
private MediaPlayer mediaPlayer2;

public static final String URL_1 = "https://www.example.com/video1.mp4";
public static final String URL_2 = "https://www.example.com/video2.mp4";

public static final String TAG = "PrebufferingActivity";

public boolean FIRST_TIME = true;

@SuppressLint("NewApi")
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_prebuffering);

    player1 = (VideoView) findViewById(R.id.videoPlayer1);
    player2 = (VideoView) findViewById(R.id.videoPlayer2);

    player1.setOnPreparedListener(new OnPreparedListener(){
        @Override
        public void onPrepared(MediaPlayer mp)          {
            mediaPlayer1 = mp;

            if(FIRST_TIME == true)
            {
                mediaPlayer1.start();
                player1.requestFocus();
                FIRST_TIME = false;
            }
        }
    });

    player2.setOnPreparedListener(new OnPreparedListener(){
        @Override
        public void onPrepared(MediaPlayer mp) {
            mediaPlayer2 = mp;
        }
    });

    player1.setOnInfoListener(new OnInfoListener(){
        @Override
        public boolean onInfo(MediaPlayer mp, int what, int extra)          {
            if(what == MediaPlayer.MEDIA_INFO_VIDEO_RENDERING_START){
                // Prepare Play 1
                mediaPlayer2.reset();

                try {
                    mediaPlayer2.setDataSource(PrebufferingActivity.this, Uri.parse(URL_2));
                } catch (Exception e) {
                    e.printStackTrace();
                } 

                mediaPlayer2.prepareAsync();
            }
            return false;
        }
    });

    player2.setOnInfoListener(new OnInfoListener(){
        @Override
        public boolean onInfo(MediaPlayer mp, int what, int extra) {
            if(what == MediaPlayer.MEDIA_INFO_VIDEO_RENDERING_START){
                // Prepare Player 2
                mediaPlayer1.reset();

                try {
                    mediaPlayer1.setDataSource(PrebufferingActivity.this, Uri.parse(URL_1));
                } catch (Exception e) {
                    e.printStackTrace();
                } 

                mediaPlayer1.prepareAsync();
            }

            return false;
        }
    });

    player1.setOnCompletionListener(new OnCompletionListener(){
        @Override
        public void onCompletion(MediaPlayer mp)            {
            mediaPlayer2.start();
            player2.requestFocus();

            // Toggle visibility
            player2.setVisibility(View.VISIBLE);
            player1.setVisibility(View.INVISIBLE);
        }
    });

    player2.setOnCompletionListener(new OnCompletionListener(){
        @Override
        public void onCompletion(MediaPlayer mp) 
        {
            mediaPlayer1.start();
            player1.requestFocus();

            // Toggle visibility
            player1.setVisibility(View.VISIBLE);
            player2.setVisibility(View.INVISIBLE);
        }
    });

    player1.setOnErrorListener(new OnErrorListener(){
        @Override
        public boolean onError(MediaPlayer mp, int what, int extra) {
            return false;
        }
    });

    player2.setOnErrorListener(new OnErrorListener(){
        @Override
        public boolean onError(MediaPlayer mp, int what, int extra) {
            return false;
        }
    });

    // Player 1
    player1.setMediaController(new MediaController(this));
    player1.setVideoURI(Uri.parse(URL_1));

    // Player 2
    player2.setMediaController(new MediaController(this));
    player2.setVideoURI(Uri.parse(URL_2));
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.prebuffering, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

}

异常

01-19 17:35:12.810: E/AndroidRuntime(30674): FATAL EXCEPTION: main
01-19 17:35:12.810: E/AndroidRuntime(30674): Process: com.my_package, PID: 30674
01-19 17:35:12.810: E/AndroidRuntime(30674): java.lang.IllegalStateException
01-19 17:35:12.810: E/AndroidRuntime(30674):    at android.media.MediaPlayer._reset(Native Method)
01-19 17:35:12.810: E/AndroidRuntime(30674):    at android.media.MediaPlayer.reset(MediaPlayer.java:1763)
01-19 17:35:12.810: E/AndroidRuntime(30674):    at com.test.PrebufferingActivity$4.onInfo(PrebufferingActivity.java:120)
01-19 17:35:12.810: E/AndroidRuntime(30674):    at android.widget.VideoView$4.onInfo(VideoView.java:487)
01-19 17:35:12.810: E/AndroidRuntime(30674):    at android.media.MediaPlayer$EventHandler.handleMessage(MediaPlayer.java:2994)
01-19 17:35:12.810: E/AndroidRuntime(30674):    at android.os.Handler.dispatchMessage(Handler.java:102)
01-19 17:35:12.810: E/AndroidRuntime(30674):    at android.os.Looper.loop(Looper.java:157)
01-19 17:35:12.810: E/AndroidRuntime(30674):    at android.app.ActivityThread.main(ActivityThread.java:5356)
01-19 17:35:12.810: E/AndroidRuntime(30674):    at java.lang.reflect.Method.invokeNative(Native Method)
01-19 17:35:12.810: E/AndroidRuntime(30674):    at java.lang.reflect.Method.invoke(Method.java:515)
01-19 17:35:12.810: E/AndroidRuntime(30674):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
01-19 17:35:12.810: E/AndroidRuntime(30674):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
01-19 17:35:12.810: E/AndroidRuntime(30674):    at dalvik.system.NativeStart.main(Native Method)