Android學習:SeekBar實現音量調節
阿新 • • 發佈:2019-02-12
SeekBar可以通過滑塊的位置來標識數值----而且拖動條允許使用者拖動滑塊來改變值,因此拖動條通常用於對系統的某種數值進行調節,比如調節音量等。
SeekBar允許使用者改變拖動條的滑塊外觀,改變滑塊外觀通常通過如下屬性來指定: android:thumb: 指定一個Drawable物件,該物件將自定義滑塊。
為了讓程式能響應拖動條滑塊位置的改變,程式可以考慮為它繫結一個OnSeekBarChangeListener監聽器。
以下是一個使用SeekBar來調節系統音量的例項:
XML程式碼:
<SeekBar android:id="@+id/sound" android:layout_width="150px" android:layout_height="10px" android:max="100" //設定拖動條最大值 android:progress="10" //設定拖動條當前值 android:progressDrawable="@layout/seekbar_style" //拖動條樣式 android:thumb="@layout/thumb" /> //滑塊樣式
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="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:
<?xml version="1.0" encoding="UTF-8"?> <selector xmlns:android="http://schemas.android.com/apk/res/android"> <!-- 按下狀態 --> <item android:state_pressed="true" android:drawable="@drawable/thumb_normal" /> <!-- 普通無焦點狀態 --> <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程式碼:
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 ; //顯示當前音量
public SeekBar soundBar;
private int maxVolume, currentVolume;
private int volume=0; //初始化聲音
@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); //音量設定
mVolume = (TextView)findViewById(R.id.mVolume);
audiomanage = (AudioManager)getSystemService(Context.AUDIO_SERVICE);
maxVolume = audiomanage.getStreamMaxVolume(AudioManager.STREAM_MUSIC); //獲取系統最大音量
soundBar.setMax(maxVolume); //拖動條最高值與系統最大聲匹配
currentVolume = audiomanage.getStreamVolume(AudioManager.STREAM_MUSIC); //獲取當前值
soundBar.setProgress(currentVolume);
mVolume.setText(currentVolume*100/maxVolume + " %");
soundBar.setOnSeekBarChangeListener(new OnSeekBarChangeListener() //調音監聽器
{
public void onProgressChanged(SeekBar arg0,int progress,boolean fromUser)
{
audiomanage.setStreamVolume(AudioManager.STREAM_MUSIC, progress, 0);
currentVolume = audiomanage.getStreamVolume(AudioManager.STREAM_MUSIC); //獲取當前值
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
}
});
TextView的XML沒有給出,需要自己新增。
完成效果: