Android提高之MediaPlayer音視頻播放

前面文章已經詳細介紹了Android界面的入門技術，相信大家在看完和跟著練習之後，會對於常用的Layout和View都會有一定的了解了,接下來就不再強調介紹界面了，而是針對具體的常見功能而展開。

本文將介紹MediaPlayer的使用。MediaPlayer可以播放音頻和視頻，另外也可以通過VideoView來播放視頻，雖然VideoView比MediaPlayer簡單易用，但定制性不如用MediaPlayer，這需要視情況選擇。MediaPlayer播放音頻比較簡單，但是要播放視頻就需要SurfaceView。SurfaceView比普通的自定義View更有繪圖上的優勢，它支持完全的OpenGL ES庫。

先貼出本文程序運行結果的截圖，上面是播放/停止音頻，可用SeekBar來調進度，下面是播放/停止視頻，也是用SeekBar來調進度：

main.xml的源碼如下:

<?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="播放音頻"></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="播放視頻"></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>

Java部分源碼有點長，需要大家耐心解讀，詳細程序如下：

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;//互斥變量，防止定時器與SeekBar拖動時進度沖突
   @Override 
  public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.main); 
    
    //----------Media控件設置---------//
    m=new MediaPlayer();
    
    //播放結束之後彈出提示
    m.setOnCompletionListener(new MediaPlayer.OnCompletionListener(){
  @Override
  public void onCompletion(MediaPlayer arg0) {
  Toast.makeText(testMedia.this, "結束", 1000).show();
  m.release();
  }
    });
    
   //----------定時器記錄播放進度---------//
    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);
  } 
 /*
  * 按鍵事件處理
  */
 class ClickEvent implements View.OnClickListener{
 @Override
 public void onClick(View v) {
 if(v==btn_start_audio)
 {
  m.reset();//恢復到未初始化的狀態
  m=MediaPlayer.create(testMedia.this, R.raw.big);//讀取音頻
  skb_audio.setMax(m.getDuration());//設置SeekBar的長度
  try {   
  m.prepare(); //准備
  } 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();//恢復到未初始化的狀態
  m=MediaPlayer.create(testMedia.this, R.raw.test);//讀取視頻
  skb_video.setMax(m.getDuration());//設置SeekBar的長度
  m.setAudioStreamType(AudioManager.STREAM_MUSIC);
  m.setDisplay(surfaceHolder);//設置屏幕
  
  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進度改變事件
  */
 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; 
 }
 }
}