我创建一个视频录像机和想创建视频播放器preVIEW录制的视频。修改code from此页面我创建了一个媒体preVIEW类的方式如下：

I am creating a video recorder and would like to create video player to preview the recorded videos. Modifying the code from this page I have created a MediaPreview class the following way:

public class MediaPreview extends Activity implements OnErrorListener, 

OnBufferingUpdateListener,
OnCompletionListener, OnPreparedListener, SurfaceHolder.Callback{

private static final String TAG = "MediaPreview";

private MediaPlayer mp;
private SurfaceView mPreview;
private SurfaceHolder holder;
private Button btnPlay;
private Button btnPause;
private Button btnReset;
private Button btnStop;

private String mPath;

@Override
protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.media_preview);

    mPreview = (SurfaceView)findViewById(R.id.mPreview);
    btnPlay = (Button)findViewById(R.id.btnPlay);
    btnPause = (Button)findViewById(R.id.btnPause);
    btnReset = (Button)findViewById(R.id.btnReset);
    btnStop = (Button)findViewById(R.id.btnStop);

    getPathFromParentDialog();

    btnPlay.setOnClickListener(new View.OnClickListener(){

        @Override
        public void onClick(View v) {
            playVideo();
        }
    });

    btnPause.setOnClickListener(new View.OnClickListener(){

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            if(mp != null){
                mp.pause();
            }
        }
    });

    btnReset.setOnClickListener(new View.OnClickListener(){

        @Override
        public void onClick(View v) {
            if(mp != null){
                mp.seekTo(0);
            }
        }
    });

    btnStop.setOnClickListener(new View.OnClickListener(){

        @Override
        public void onClick(View v) {
            if(mp != null){
                mp.stop();
                mp.release();
            }
        }
    });

    getWindow().setFormat(PixelFormat.TRANSPARENT);
    holder = mPreview.getHolder();
    holder.addCallback(this);
    holder.setFixedSize(400, 300);
}

@Override
protected void onResume() {

    setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
    super.onResume();
}

@Override
public boolean onError(MediaPlayer mp, int what, int extra) {
    if(mp != null){
        mp.stop();
        mp.release();
    }
    return false;
}

@Override
public void onBufferingUpdate(MediaPlayer mp, int percent) {
    // TODO Auto-generated method stub

}

@Override
public void onCompletion(MediaPlayer mp) {
    // TODO Auto-generated method stub

}

@Override
public void onPrepared(MediaPlayer mp) {
    // TODO Auto-generated method stub

}

@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

}

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

}

private void playVideo() {
    try{
        mp = new MediaPlayer();
        mp.setOnErrorListener(this);
        mp.setOnBufferingUpdateListener(this);
        mp.setOnCompletionListener(this);
        mp.setOnPreparedListener(this);
        mp.setAudioStreamType(2);

        mp.setDisplay(mPreview.getHolder());
        Runnable r = new Runnable(){
            @Override
            public void run() {
                try{
                    setDataSource(mPath);
                }
                catch(Exception ex){
                    Log.e(TAG, ex.getMessage());
                }
                try {
                    mp.prepare();
                    Log.v(TAG, "Duration: ===> " + mp.getDuration());
                } catch (IllegalStateException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                    Log.e(TAG, e.getMessage());
                }
                mp.start();
            }

        };
        new Thread(r).start();
    }
    catch(Exception ex){
        String sDummy = ex.toString();
        if(mp != null){
            mp.stop();
            mp.release();
        }
    }

}

private void setDataSource(String path) throws IOException {
    if(!URLUtil.isNetworkUrl(mPath)){
        mp.setDataSource(mPath);
    }
    else{
        URL url = new URL(mPath);
        URLConnection cn = url.openConnection();
        cn.connect();
        InputStream stream = cn.getInputStream();
        if(stream == null){
            throw new RuntimeException("stream is null");
        }
        File fileTemp = File.createTempFile("mediaplayerTmp", "dat");
        String tempPath = fileTemp.getAbsolutePath();
        FileOutputStream out = new FileOutputStream(fileTemp);
        byte buf[] = new byte[128];
        do{
            int numRead = stream.read(buf);
            if(numRead <= 0){
                break;
            }
            out.write(buf, 0, numRead);
        }while(true);
        mp.setDataSource(tempPath);
        try{
            stream.close();
        }
        catch(Exception ex){
            String sDummy = ex.toString();
        }
    }
}

private void getPathFromParentDialog()
{
    Intent intent = getIntent();
    mPath = intent.getExtras().getString(MediaLibrary.FILENAME);
}
}

在code执行成功（没有任何例外）直到mp.start（）; ，但屏幕是空白的（只有在屏幕上的按钮）

The code successfully executes (without any exceptions) until mp.start();, but the screen is blank (there are only buttons on the screen).

有谁知道什么可能是错误的，在code以上还是有说在网络上的作品提供任何例子吗？

Does anyone know what could be wrong in the code above or is there any example that works available on the web?

我真的AP preciate你的帮助

I would really appreciate your help

推荐答案

即兴，我认为你需要在你的一些回调方法，多了一些逻辑，比如 surfaceCreated（）。

Off the cuff, I think you need some more logic in some of your callback methods, like surfaceCreated().