前面文章已经详细介绍了Android界面的入门技术，相信大家在看完和跟着练习之后，会对于常用的Layout和View都会有一定的了解了,接下来就不再强调介绍界面了，而是针对具体的常见功能而展开。
本文将介绍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，这需要视情况选择。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>
Java部分源码有点长，需要大家耐心解读，详细程序如下：
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;
}
}
}
