MediaPlayer MediaController

最近为了比较全面的了解一下Android的知识体系结构，买了一个Android4 高级编程研读一下，在学习第十五章音频、视频以及摄像头的使用的时候，书本上的MediaPlayer和MediaController联合使用的例子没有调通。搜索良久找到答案在此记录一下。

1.MediaPlayer 播放视频

使用的布局文件如下：

<?xml version="1.0" encoding="utf-8"?>
<!-- Listing 15-3: Sample layout using a Surface View -->
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" >
    <SurfaceView  android:id="@+id/surfaceView" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_weight="30" />
    <LinearLayout  android:id="@+id/ll" android:layout_width="match_parent" android:layout_height="100dp" android:orientation="horizontal" >
    </LinearLayout>
</LinearLayout>

相关Java代码如下：

package com.paad.mediaplayer;

import java.io.IOException;

import android.app.Activity;
import android.media.MediaPlayer;
import android.media.MediaPlayer.OnPreparedListener;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.widget.MediaController;
import constant.Constants;

public class AudioPlayer extends Activity implements OnPreparedListener, MediaController.MediaPlayerControl {
    private static final String TAG = "AudioPlayer";
    private MediaPlayer mediaPlayer;
    private MediaController mediaController;
    private Handler handler = new Handler();

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.surfaceviewvideoviewer);
        mediaPlayer = new MediaPlayer();
        mediaPlayer.setOnPreparedListener(this);
        try {
            //TODO 这里填写你的本地视频文件路径
            mediaPlayer.setDataSource(Constants.PATH_VEDIO);
            mediaPlayer.prepare();
            mediaPlayer.start();
        } catch (IOException e) {
            Log.e(TAG, "Could not open file xxx for playback.", e);
        }

        final SurfaceView surfaceView = (SurfaceView) findViewById(R.id.surfaceView);
        surfaceView.setKeepScreenOn(true);
        SurfaceHolder surfaceHolder = surfaceView.getHolder();
        surfaceHolder.addCallback(new SurfaceHolder.Callback() {

            @Override
            public void surfaceDestroyed(SurfaceHolder holder) {
                mediaPlayer.release();
            }

            @Override
            public void surfaceCreated(SurfaceHolder holder) {
                mediaPlayer.setDisplay(holder);
            }

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

            }
        });
        surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
        surfaceHolder.setFixedSize(400, 300);

    }
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        // the MediaController will hide after 3 seconds - tap the screen to
        // make it appear again
        mediaController.show();
        return false;
    }

    // --MediaPlayerControl
    // methods----------------------------------------------------
    public void start() {
        mediaPlayer.start();
    }

    public void pause() {
        mediaPlayer.pause();
    }

    public int getDuration() {
        return mediaPlayer.getDuration();
    }

    public int getCurrentPosition() {
        return mediaPlayer.getCurrentPosition();
    }

    public void seekTo(int i) {
        mediaPlayer.seekTo(i);
    }

    public boolean isPlaying() {
        return mediaPlayer.isPlaying();
    }

    public int getBufferPercentage() {
        return 0;
    }

    public boolean canPause() {
        return true;
    }

    public boolean canSeekBackward() {
        return true;
    }

    public boolean canSeekForward() {
        return true;
    }

    // --------------------------------------------------------------------------------

    public void onPrepared(MediaPlayer mediaPlayer) {
        Log.d(TAG, "onPrepared");
        mediaController = new MediaController(this);
        mediaController.setMediaPlayer(this);
        mediaController.setAnchorView(findViewById(R.id.ll));
        mediaController.setEnabled(true);

        handler.post(new Runnable() {
            public void run() {
                mediaController.show();
            }
        });
    }

    @Override
    public int getAudioSessionId() {
        // TODO Auto-generated method stub
        return 0;
    }
}

代码罗列在这里了，我还想啰嗦几句：
1.OnPreparedListener不是必须的，主要是为mediaController.show();服务的，将onPrepared中的代码块移动到onCreate里面也是ok的，但是，要做稍微的调整，将handler.post修改为了handler.postDelayed，设置一个延迟执行的时间（让mediaPlayer完成播放前的初始化）也是ok的。
2.至于为什么在代码初始化后，调用mediaController.show()必须放到handler.post中，我猜想是因为mediaController的初始化也是通过handler机制进行更新的，通过handler是通过队列机制对消息进行处理了，这样就保证了mediaController的初始化和mediaController.show的顺序。
3.至于为什么将mediaPlayer.setDisplay(holder);设置放到surfaceCreated方法中，SurfaceView的创建是异步的，实例化后，并没有完成创建。

2.MediaPlayer播放音频

这个就要简单的多了，不需要SurfaceView来展示视频了，下面贴一下代码：

package com.paad.mediaplayer;

import java.io.IOException;

import android.app.Activity;
import android.media.MediaPlayer;
import android.media.MediaPlayer.OnPreparedListener;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.view.MotionEvent;
import android.widget.LinearLayout;
import android.widget.MediaController;
import constant.Constants;

public class AudioPlayer extends Activity implements OnPreparedListener, MediaController.MediaPlayerControl {
    private static final String TAG = "AudioPlayer";
    private MediaPlayer mediaPlayer;
    private MediaController mediaController;
    private Handler handler = new Handler();
    private LinearLayout mControllLayout;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mControllLayout=new LinearLayout(this);
        setContentView(mControllLayout);
        mediaPlayer = new MediaPlayer();
        mediaPlayer.setOnPreparedListener(this);
        try {
            //TODO 这里写你的音频路径
            mediaPlayer.setDataSource(Constants.PATH_AUDIO);
            mediaPlayer.prepare();
            mediaPlayer.start();
        } catch (IOException e) {
            Log.e(TAG, "Could not open file xxx for playback.", e);
        }

    }
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        // the MediaController will hide after 3 seconds - tap the screen to
        // make it appear again
        mediaController.show();
        return false;
    }

    // --MediaPlayerControl
    // methods----------------------------------------------------
    public void start() {
        mediaPlayer.start();
    }

    public void pause() {
        mediaPlayer.pause();
    }

    public int getDuration() {
        return mediaPlayer.getDuration();
    }

    public int getCurrentPosition() {
        return mediaPlayer.getCurrentPosition();
    }

    public void seekTo(int i) {
        mediaPlayer.seekTo(i);
    }

    public boolean isPlaying() {
        return mediaPlayer.isPlaying();
    }

    public int getBufferPercentage() {
        return 0;
    }

    public boolean canPause() {
        return true;
    }

    public boolean canSeekBackward() {
        return true;
    }

    public boolean canSeekForward() {
        return true;
    }

    public void onPrepared(MediaPlayer mediaPlayer) {
        Log.d(TAG, "onPrepared");
        mediaController = new MediaController(this);
        mediaController.setMediaPlayer(this);
        mediaController.setAnchorView(mControllLayout);
        mediaController.setEnabled(true);
        handler.post(new Runnable() {
            public void run() {
                mediaController.show();
            }
        });
    }

    @Override
    public int getAudioSessionId() {
        // TODO Auto-generated method stub
        return 0;
    }
}