下文来自：
http://www.itivy.com/android/archive/2011/7/10/android-set-voice-seekbar.html
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很多音乐播放器界面上都有一个音量seekbar，那么在android里面是如何实现的呢？
首先分析下要解决的问题：
1.获取媒体播放的音量。
2.通过seekbar可以增减音量
3.用户按下音量键增减音量，seekbar保持同步
对于第一个问题：Android系统提供AudioManager类来获得系统audio服务。
对于第二个问题：实现seekBarChangeLIstener里面onProgressChanged方法。
对于第三个问题：用线程来同步更新UI。
设置音量的代码：
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private setVolum(){ maxVolume = mAudioManager.getStreamMaxVolume(AudioManager.STREAM_MUSIC); volSeekBar.setMax(maxVolume); currentVolume = mAudioManager.getStreamVolume(AudioManager.STREAM_MUSIC); volSeekBar.setProgress(currentVolume); mVolume.setText(currentVolume*100/maxVolume +" ");} |
实现seekbar控制音量代码：
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OnSeekBarChangeListener seekBarChangeListener =new OnSeekBarChangeListener(){ publicvoid onProgressChanged(SeekBar seekBar,int progress, booleanfromUser) { // TODO Auto-generated method stub mAudioManager.setStreamVolume(AudioManager.STREAM_MUSIC, progress,0); } publicvoid onStartTrackingTouch(SeekBar seekBar) { // TODO Auto-generated method stub } publicvoid onStopTrackingTouch(SeekBar seekBar) { // TODO Auto-generated method stub }}; |
线程更新UI代码：
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Handler myHandler =new Handler(){ publicvoid handleMessage(Message msg) { switch(msg.what) { casePROGRESS_CHANGED: setVolum(); /*sendEmptyMessageDelayed(PROGRESS_CHANGED, 200);*/ break; } } }; classmyVolThread implementsRunnable { publicvoid run() { while(!Thread.currentThread().isInterrupted()) { Message message =new Message(); message.what =PROGRESS_CHANGED; MainActivity.this.myHandler.sendMessage(message); try{ Thread.sleep(100); }catch (InterruptedException e) { Thread.currentThread().interrupt(); } } } } |
最后贴上MainActivity代码：
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public MainActivity extendsActivity { protectedstatic final PROGRESS_CHANGED = 0x101; privateSeekBar volSeekBar ; privateTextView mVolume ; privateAudioManager mAudioManager; privateint maxVolume, currentVolume; Thread myVolThread =null; Handler myHandler =new Handler(){ publicvoid handleMessage(Message msg) { switch(msg.what) { casePROGRESS_CHANGED: setVolum(); /*sendEmptyMessageDelayed(PROGRESS_CHANGED, 200);*/ break; } } }; publicvoid onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); volSeekBar= (SeekBar)findViewById(R.id.volum_seek); mVolume = (TextView)findViewById(R.id.volum_val); mAudioManager = (AudioManager)getSystemService(Context.AUDIO_SERVICE); //setVolum(); OnSeekBarChangeListener seekBarChangeListener =new OnSeekBarChangeListener() { publicvoid onProgressChanged(SeekBar seekBar,int progress, booleanfromUser) { // TODO Auto-generated method stub mAudioManager.setStreamVolume(AudioManager.STREAM_MUSIC, progress,0); } publicvoid onStartTrackingTouch(SeekBar seekBar) { // TODO Auto-generated method stub } publicvoid onStopTrackingTouch(SeekBar seekBar) { // TODO Auto-generated method stub } }; volSeekBar.setOnSeekBarChangeListener(seekBarChangeListener); newThread(new } privatevoid setVolum() { maxVolume = mAudioManager.getStreamMaxVolume(AudioManager.STREAM_MUSIC); volSeekBar.setMax(maxVolume); currentVolume = mAudioManager.getStreamVolume(AudioManager.STREAM_MUSIC); volSeekBar.setProgress(currentVolume); mVolume.setText(currentVolume*100/maxVolume +" "); } classmyVolThread implementsRunnable { publicvoid run() { while(!Thread.currentThread().isInterrupted()) { Message message =new Message(); message.what =PROGRESS_CHANGED; MainActivity.this.myHandler.sendMessage(message); try{ Thread.sleep(100); }catch (InterruptedException e) { Thread.currentThread().interrupt(); } } } } }
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注：原来我为了保持与 系统按键操作的统一，在Acitity中通过
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
switch (keyCode){
case KeyEvent.KEYCODE_VOLUME_DOWN:
ddApplication.reSaveMusicVolume();
break;
case KeyEvent.KEYCODE_VOLUME_UP:
ddApplication.reSaveMusicVolume();
break;
}
musicControl.setProgress(ddApplication.getMusicVolume()); // 这一句不起作用啊
return super.onKeyDown(keyCode, event);
}
结果发现并不能实现同步的效果，遂找得上篇来作参考！