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：

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<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

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<?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:

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<?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>

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<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：

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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

}

});