Android提高第一篇之MediaPlayer

http://blog.csdn.net/hellogv/archive/2010/10/30/5975864.aspx
前面写了十四篇关于界面的入门文章，大家都看完和跟着练习之后，对于常用的Layout和View都会有一定的了解了,接下来的文章就不再强调介绍界面了，而是针对具体的常见功能而展开。

        本文介绍MediaPlayer的使用。MediaPlayer可以播放音频和视频，另外也可以通过VideoView来播放视频，虽然VideoView比MediaPlayer简单易用，但定制性不如用MediaPlayer，要视情况选择了。MediaPlayer播放音频比较简单，但是要播放视频就需要SurfaceView。SurfaceView比普通的自定义View更有绘图上的优势，它支持完全的OpenGL ES库。

         先贴出本文程序运行结果的截图，上面是播放/停止音频，可用SeekBar来调进度，下面是播放/停止视频，也是用SeekBar来调进度：



main.xml的源码:

<?xml version="1.0" encoding="utf-8"?>  
<LinearLayout android:id="@+id/LinearLayout01"  
    android:layout_width="fill_parent" android:layout_height="fill_parent"  
    xmlns:android="http://schemas.android.com/apk/res/android"  
    android:orientation="vertical">  
    <SeekBar android:id="@+id/SeekBar01" android:layout_height="wrap_content"  
        android:layout_width="fill_parent"></SeekBar>  
    <LinearLayout android:id="@+id/LinearLayout02"  
        android:layout_width="wrap_content" android:layout_height="wrap_content">  
        <Button android:id="@+id/Button01" android:layout_width="wrap_content"  
            android:layout_height="wrap_content" android:text="播放音频"></Button>  
        <Button android:id="@+id/Button02" android:layout_width="wrap_content"  
            android:layout_height="wrap_content" android:text="停止播放"></Button>  
    </LinearLayout>  
    <SeekBar android:id="@+id/SeekBar02" android:layout_height="wrap_content"  
        android:layout_width="fill_parent"></SeekBar>  
  
    <SurfaceView android:id="@+id/SurfaceView01"  
        android:layout_width="fill_parent" android:layout_height="250px"></SurfaceView>  
    <LinearLayout android:id="@+id/LinearLayout02"  
        android:layout_width="wrap_content" android:layout_height="wrap_content">  
        <Button android:layout_width="wrap_content"  
            android:layout_height="wrap_content" android:id="@+id/Button03"  
            android:text="播放视频"></Button>  
        <Button android:layout_width="wrap_content"  
            android:layout_height="wrap_content" android:text="停止播放" android:id="@+id/Button04"></Button>  
    </LinearLayout>  
</LinearLayout>  

本文程序的源码，有点长：

package com.testMedia;  
  
import java.io.IOException;    
import java.util.Timer;  
import java.util.TimerTask;  
import android.app.Activity;    
import android.media.AudioManager;  
import android.media.MediaPlayer;  
import android.os.Bundle;    
import android.view.SurfaceHolder;  
import android.view.SurfaceView;  
import android.view.View;    
import android.widget.Button;    
import android.widget.SeekBar;  
import android.widget.Toast;    
  
  
public class testMedia extends Activity {  
      /** Called when the activity is first created. */   
  
    private SeekBar skb_audio=null;  
    private Button btn_start_audio = null;    
    private Button btn_stop_audio = null;  
  
    private SeekBar skb_video=null;  
    private Button btn_start_video = null;    
    private Button btn_stop_video = null;  
    private SurfaceView surfaceView;   
    private SurfaceHolder surfaceHolder;   
      
    private MediaPlayer m = null;    
    private Timer mTimer;  
    private TimerTask mTimerTask;  
      
    private boolean isChanging=false;//互斥变量，防止定时器与SeekBar拖动时进度冲突  
     @Override    
    public void onCreate(Bundle savedInstanceState) {    
        super.onCreate(savedInstanceState);    
        setContentView(R.layout.main);    
          
        //----------Media控件设置---------//  
        m=new MediaPlayer();  
          
        //播放结束之后弹出提示  
        m.setOnCompletionListener(new MediaPlayer.OnCompletionListener(){  
            @Override  
            public void onCompletion(MediaPlayer arg0) {  
                Toast.makeText(testMedia.this, "结束", 1000).show();  
                m.release();  
            }  
        });  
          
      //----------定时器记录播放进度---------//  
        mTimer = new Timer();  
        mTimerTask = new TimerTask() {  
            @Override  
            public void run() {   
                if(isChanging==true)  
                    return;  
                  
                if(m.getVideoHeight()==0)  
                    skb_audio.setProgress(m.getCurrentPosition());  
                else   
                    skb_video.setProgress(m.getCurrentPosition());  
            }  
        };  
  
        mTimer.schedule(mTimerTask, 0, 10);  
          
        btn_start_audio = (Button) this.findViewById(R.id.Button01);    
        btn_stop_audio = (Button) this.findViewById(R.id.Button02);    
        btn_start_audio.setOnClickListener(new ClickEvent());  
        btn_stop_audio.setOnClickListener(new ClickEvent());  
        skb_audio=(SeekBar)this.findViewById(R.id.SeekBar01);  
        skb_audio.setOnSeekBarChangeListener(new SeekBarChangeEvent());  
          
        btn_start_video = (Button) this.findViewById(R.id.Button03);    
        btn_stop_video = (Button) this.findViewById(R.id.Button04);    
        btn_start_video.setOnClickListener(new ClickEvent());  
        btn_stop_video.setOnClickListener(new ClickEvent());  
        skb_video=(SeekBar)this.findViewById(R.id.SeekBar02);  
        skb_video.setOnSeekBarChangeListener(new SeekBarChangeEvent());  
        surfaceView = (SurfaceView) findViewById(R.id.SurfaceView01);  
        surfaceHolder = surfaceView.getHolder();  
        surfaceHolder.setFixedSize(100, 100);  
        surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);  
    }    
       
  /* 
   * 按键事件处理 
   */  
  class ClickEvent implements View.OnClickListener{  
    @Override  
    public void onClick(View v) {  
        if(v==btn_start_audio)  
        {  
            m.reset();//恢复到未初始化的状态  
            m=MediaPlayer.create(testMedia.this, R.raw.big);//读取音频  
            skb_audio.setMax(m.getDuration());//设置SeekBar的长度  
            try {                     
                m.prepare();    //准备  
            } catch (IllegalStateException e) {           
                // TODO Auto-generated catch block                
                e.printStackTrace();                  
            } catch (IOException e) {             
                // TODO Auto-generated catch block                
                e.printStackTrace();                  
            }         
            m.start();  //播放  
        }  
        else if(v==btn_stop_audio || v==btn_stop_video)  
        {  
            m.stop();  
        }  
        else if(v==btn_start_video)  
        {  
            m.reset();//恢复到未初始化的状态  
            m=MediaPlayer.create(testMedia.this, R.raw.test);//读取视频  
            skb_video.setMax(m.getDuration());//设置SeekBar的长度  
            m.setAudioStreamType(AudioManager.STREAM_MUSIC);  
            m.setDisplay(surfaceHolder);//设置屏幕  
              
            try {  
                m.prepare();  
                  
            } catch (IllegalArgumentException e) {  
                // TODO Auto-generated catch block  
                e.printStackTrace();  
            } catch (IllegalStateException e) {  
                // TODO Auto-generated catch block  
                e.printStackTrace();  
            } catch (IOException e) {  
                // TODO Auto-generated catch block  
                e.printStackTrace();  
            }  
            m.start();  
        }  
    }  
  }  
    
  /* 
   * SeekBar进度改变事件 
   */  
  class SeekBarChangeEvent implements SeekBar.OnSeekBarChangeListener{  
  
    @Override  
    public void onProgressChanged(SeekBar seekBar, int progress,  
            boolean fromUser) {  
        // TODO Auto-generated method stub  
          
    }  
  
    @Override  
    public void onStartTrackingTouch(SeekBar seekBar) {  
        isChanging=true;  
    }  
  
    @Override  
    public void onStopTrackingTouch(SeekBar seekBar) {  
        m.seekTo(seekBar.getProgress());  
        isChanging=false;     
    }  
        
  }  
  
}