请问：SurfaceView+mediaplayer有声音无视频是咋回事

请教：SurfaceView+mediaplayer有声音无视频是怎么回事？

Java code

import android.app.Activity;import android.media.AudioManager;import android.media.MediaPlayer;import android.os.Bundle;import android.view.SurfaceHolder;import android.view.SurfaceView;public class MediaPlayDemo extends Activity {    private SurfaceView surfaceView = null ;    private SurfaceHolder surfaceHolder = null ;    private MediaPlayer mp = null ;    /** Called when the activity is first created. */    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        surfaceView = new SurfaceView(this);        this.surfaceHolder = this.surfaceView.getHolder();        this.surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);        this.setContentView(this.surfaceView);                this.mp = new MediaPlayer();        try {            mp.setDataSource("/sdcard/wozhinvrenxin.mp4");        } catch (Exception e) {            // TODO Auto-generated catch block            e.printStackTrace();        }        this.mp.setDisplay(surfaceHolder);        this.mp.setAudioStreamType(AudioManager.STREAM_MUSIC);        try {            this.mp.prepare();        } catch (Exception e) {            // TODO Auto-generated catch block            e.printStackTrace();        }        this.mp.start();    }}

------解决方案--------------------
原因是：MediaPlayer开始播放后，SurfaceView还没有创建出来，因此会出现有声音没图像，解决办法：

通过surfaceHolder.addCallback监听surfaceCreate事件后再播放；

public class MediaPlayDemo extends Activity implements SurfaceHolder.Callback
{
private SurfaceView surfaceView = null ;
private SurfaceHolder surfaceHolder = null ;
private MediaPlayer mp = null ;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
surfaceView = new SurfaceView(this);
surfaceHolder = surfaceView.getHolder();
surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
surfaceHolder.addCallback(this);
setContentView(surfaceView);


}

@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub

}

@Override
public void surfaceCreated(SurfaceHolder holder) {
// TODO Auto-generated method stub
mp = new MediaPlayer();
mp.setAudioStreamType(AudioManager.STREAM_MUSIC);
mp.setDisplay(surfaceHolder);
try {
mp.setDataSource("/sdcard/DownAndPlay/xyj.mp4");
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
mp.prepare();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
mp.start();
}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub

}

}
------解决方案--------------------
SurfaceView没有创建成功，所以没有视频