Android SeekBar实现音量调节

SeekBar可以通过滑块的位置来标识数值----而且拖动条允许用户拖动滑块来改变值，因此拖动条通常用于对系统的某种数值进行调节，比如调节音量等。

SeekBar允许用户改变拖动条的滑块外观，改变滑块外观通常通过如下属性来指定：android:thumb: 指定一个Drawable对象，该对象将自定义滑块。

为了让程序能响应拖动条滑块位置的改变，程序可以考虑为它绑定一个OnSeekBarChangeListener监听器。

以下是一个使用SeekBar来调节系统音量的实例：

XML代码：

 <SeekBar

                android:id="@+id/sound"

                android:layout_width="150px"

                android:layout_height="10px"

                android:max=""  //设置拖动条最大值

                android:progress=""   //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

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="" android:angle="" />

        </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="" android:angle="" />

            </shape>

        </clip>

    </item>

</layer-list>    

thumb.xml:

<?xml version="1.0" encoding="UTF-8"?>

<selector xmlns:android="http://schemas.android.com/apk/res/android">

    <!-- 按下状态 -->

    <item

        android:state_pressed="true"

        android:drawable="@drawable/thumb_normal"

        />

    <!-- 普通无焦点状态 -->

    <item

        android:state_focused="false"

        android:state_pressed="false"

        android:drawable="@drawable/thumb_normal"

    />

</selector>    

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>

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=;  //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*/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, );

                currentVolume = audiomanage.getStreamVolume(AudioManager.STREAM_MUSIC);  //获取当前值

                soundBar.setProgress(currentVolume);

                mVolume.setText(currentVolume*/maxVolume + " %");

            }

            @Override

            public void onStartTrackingTouch(SeekBar seekBar) {

                // TODO Auto-generated method stub

            }

            @Override

            public void onStopTrackingTouch(SeekBar seekBar) {

                // TODO Auto-generated method stub

            }

        });

TextView的XML没有给出，需要自己添加。

完成效果：