Android提高第一篇之MediaPlayer

本文来自http://blog.csdn.net/hellogv/ ，引用必须注明出处！

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;	
	}
	  
  }

}