MediaPlayer 用法(一) - 一切皆有可能 - JavaEye技术网站

2010-10-20

MediaPlayer 用法(一)

文章分类:移动开发

使用SurfaceView播放视频,其实很简单,但是经常会碰见有声音没图像的问题.

其实使用SurfaceView播放视频只需要主要下面几个地方就可以了

 

1. surfaceChanged也就是Suface是否创建成功

2. onPrepared 也就是MideoPlayer是否加载并准备完成

3. surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

类型必须是SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS

package VideoTest.Test;

import java.io.FileDescriptor;

import android.app.Activity;
import android.content.res.AssetFileDescriptor;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.media.MediaPlayer.OnBufferingUpdateListener;
import android.media.MediaPlayer.OnCompletionListener;
import android.media.MediaPlayer.OnPreparedListener;
import android.os.Bundle;
import android.view.SurfaceHolder;
import android.view.SurfaceView;


public class VideoTest extends Activity implements SurfaceHolder.Callback,
    OnBufferingUpdateListener, OnCompletionListener, OnPreparedListener{

    private SurfaceView surfaceView;
    private SurfaceHolder surfaceHolder;
    private MediaPlayer mediaPlayer;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        this.surfaceView = new SurfaceView(this);
        this.surfaceHolder = this.surfaceView.getHolder();
        this.surfaceHolder.addCallback(this);

        //类型必须设置成SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS
        this.surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
        setContentView(this.surfaceView);
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        if (this.mediaPlayer != null) {
            this.mediaPlayer.release();
            this.mediaPlayer = null;
        }
    }

    public void PlayVideo(){

        try {
            //视频文件放在 assert中
            AssetFileDescriptor aFD = this.getAssets().openFd("welcome.3gp");
            FileDescriptor fileDescriptor = aFD.getFileDescriptor();
            this.mediaPlayer = new MediaPlayer();
            this.mediaPlayer.setDataSource(fileDescriptor, aFD.getStartOffset(), aFD.getLength());
            aFD.close();

            //视频放在SDCard中
            //File sdFile = Environment.getExternalStorageDirectory();
            //this.mediaPlayer = new MediaPlayer();
            //this.mediaPlayer.setDataSource(sdFile.getAbsoluteFile() + File.separator + "welcome.3gp");

            //视频放在res中
            //this.mediaPlayer = MediaPlayer.create(this, R.raw.welcome);

            //网上的视频,没有测试
            //this.mediaPlayer
            //  .setDataSource("http://xy2.163.com/download/down/wukong.mp3");

            this.mediaPlayer.setDisplay(this.surfaceHolder);
            this.mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
            //准备完成后才可以播放,另外如果文件特别大或者从网上获得的资源
            //会在这里等待时间过长,造成堵塞,这样的话就得用
            //this.mediaPlayer.prepareAsync(),然后监听是否准备完毕在开始

            this.mediaPlayer.prepare();
            this.mediaPlayer.start();

        } catch (Exception e) {
            // TODO: handle exception
        }
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width,
            int height) {

    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        //SurfaceCreated 创建成功才可以播放视频
        PlayVideo();
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {

    }

    //@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) {
        //MediaPlayer加载准备完毕才能开始播放
        //mp.start();
    }

}

 

 

但是,对于一些人可能会产生另一个问题就是

surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

在设置成SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS类型后,无法画图了

SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS的意思是创建一个"PUSH"surface,这个surface没有自己的缓冲区,没有自己的缓冲Buffer.