Android学习：SeekBar实现音量调节

        Android学习：SeekBar实现音量调节       

2011-11-28 14:42412人阅读评论(0)收藏举报

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="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

<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

seekbar_style.xml:

<?xmlversion="1.0"encoding="UTF-8"?>
<layer-listxmlns:android="http://schemas.android.com/apk/res/android">

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

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

<?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>

thumb.xml:

<?xmlversion="1.0"encoding="UTF-8"?>
<selectorxmlns: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>

<?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>

<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：

publicclass 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;
     privateint maxVolume, currentVolume;



    privateint volume=0;  //初始化声音

    @Override
    publicvoid 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
        {
            publicvoid 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
            publicvoid onStartTrackingTouch(SeekBar seekBar) {
                // TODO Auto-generated method stub

            }
            @Override
            publicvoid onStopTrackingTouch(SeekBar seekBar) {
                // TODO Auto-generated method stub


            }
        });