Android 使用SeekBar调节系统音量

以下是一个使用SeekBar来调节系统音量的实例：
1、XML：
   <SeekBar
  android:id="@+id/sound"
  android:layout_width="150px"
  android:layout_height="10px"
  android:max="100" //设置拖动条最大值
  android:progress="10"   //设置拖动条当前值
  android:progressDrawable="@layout/seekbar_style" //拖动条样式
  android:thumb="@layout/thumb" />  //滑块样式

2、seekbar_style.xml:
<?xml version="1.0" encoding="UTF-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">

    <item android:id="@android:id/background">
        <shape>
            <corners android:radius="10dip" />
            <gradient android:startColor="#ffffffff"
                android:centerColor="#ff000000" android:endColor="#ff808A87"
                android:centerY="1" android:angle="270" />
        </shape>
    </item>

    <item android:id="@android:id/progress">
        <clip>
            <shape>
                <corners android:radius="10dip" />
                <gradient android:startColor="#ffffffff"
                    android:centerColor="#ffFFFF00" android:endColor="#ffAABD00"
                    android:centerY="1" android:angle="270" />
            </shape>
        </clip>
    </item>
</layer-list>

3、thumb.xml:
<?xml version="1.0" encoding="UTF-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
  
  <item
   android:state_pressed="true"
   android:drawable="@drawable/thumb_normal"
   />
  
  <item
   android:state_focused="false"
   android:state_pressed="false"
   android:drawable="@drawable/thumb_normal"
  />
</selector>

4、bacon_seekbar.xml:
<layer-list
   xmlns:android="http://schemas.android.com/apk/res/android">
   <item
  android:id="@+android:id/background"
  android:drawable="@drawable/thumb_normal" />
   <item
  android:id="@+android:id/SecondaryProgress"
  android:drawable="@drawable/thumb_normal" />
   <item
  android:id="@+android:id/progress"
  android:drawable="@drawable/thumb_normal" />
</layer-list>

5、JAVA代码：
public class PianoActivity extends Activity {
/** Called when the activity is first created. */
private ImageButton imageButton_white1;
private MediaPlayer mediaPlayer01;
public AudioManager audiomanage;
private TextView mVolume ; //显示当前音量
public SeekBar soundBar;
private int maxVolume, currentVolume;

private int volume=0; //初始化声音

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        mediaPlayer01 = new MediaPlayer();

        imageButton_white1=(ImageButton)findViewById(R.id.white1);
        final SeekBar soundBar=(SeekBar)findViewById(R.id.sound); //音量设置
        mVolume = (TextView)findViewById(R.id.mVolume);
        audiomanage = (AudioManager)getSystemService(Context.AUDIO_SERVICE);

        maxVolume = audiomanage.getStreamMaxVolume(AudioManager.STREAM_MUSIC); //获取系统最大音量
        soundBar.setMax(maxVolume);   //拖动条最高值与系统最大声匹配
        currentVolume = audiomanage.getStreamVolume(AudioManager.STREAM_MUSIC); //获取当前值
        soundBar.setProgress(currentVolume);
        mVolume.setText(currentVolume*100/maxVolume + " %");

        soundBar.setOnSeekBarChangeListener(new OnSeekBarChangeListener(){调音监听器
       　　 public void onProgressChanged(SeekBar arg0,int progress,boolean fromUser){
            　　  audiomanage.setStreamVolume(AudioManager.STREAM_MUSIC, progress, 0);
           　　   currentVolume = audiomanage.getStreamVolume(AudioManager.STREAM_MUSIC); //获取当前值
            　　 soundBar.setProgress(currentVolume);
          　　    mVolume.setText(currentVolume*100/maxVolume + " %");
       　　 }
       　　
   　　　@Override
  　　　　public void onStartTrackingTouch(SeekBar seekBar) {
   　　  　　   // TODO Auto-generated method stub
    　　   }
   　　　 @Override
  　　　　public void onStopTrackingTouch(SeekBar seekBar) {
  　　　　    // TODO Auto-generated method stub