Android音量seekbar制作

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：

1 private void setVolum()
2     {
3         
4         maxVolume = mAudioManager.getStreamMaxVolume(AudioManager.STREAM_MUSIC);
5         volSeekBar.setMax(maxVolume);
6         currentVolume = mAudioManager.getStreamVolume(AudioManager.STREAM_MUSIC);
7         volSeekBar.setProgress(currentVolume);
8         mVolume.setText(currentVolume*100/maxVolume + " ");
9     }

　　实现seekbar控制音量代码：

OnSeekBarChangeListener seekBarChangeListener = new OnSeekBarChangeListener()
        {

            public void onProgressChanged(SeekBar seekBar, int progress,
                    boolean fromUser) {
                // TODO Auto-generated method stub
                mAudioManager.setStreamVolume(AudioManager.STREAM_MUSIC, progress, 0);
            }

            public void onStartTrackingTouch(SeekBar seekBar) {
                // TODO Auto-generated method stub
                
            }

            public void onStopTrackingTouch(SeekBar seekBar) {
                // TODO Auto-generated method stub
                
            }
            
        };

　　　　线程更新UI代码：

 1 Handler myHandler = new Handler(){
 2         public void handleMessage(Message msg) {  
 3             switch (msg.what) {  
 4             case PROGRESS_CHANGED:  
 5                 setVolum();  
 6                 /*sendEmptyMessageDelayed(PROGRESS_CHANGED, 200);*/
 7                 break;
 8            }
 9         }
10     };
11 
12  class myVolThread implements Runnable {   
13         public void run() {  
14              while (!Thread.currentThread().isInterrupted()) {    
15                      
16                   Message message = new Message();   
17                   message.what =PROGRESS_CHANGED;   
18                   MainActivity.this.myHandler.sendMessage(message);   
19                   try {   
20                        Thread.sleep(100);    
21                   } catch (InterruptedException e) {   
22                        Thread.currentThread().interrupt();   
23                   }   
24              }   
25         }   
26    }

最后贴上MainActivity代码：

01
public class MainActivity extends Activity { 

02
      
03
    protected static final int PROGRESS_CHANGED = 0x101; 

04
    private SeekBar volSeekBar ; 

05
    private TextView mVolume ; 

06
    private AudioManager mAudioManager; 

07
    private int maxVolume, currentVolume; 

08
      
09
    Thread myVolThread = null; 

10
    Handler myHandler = new Handler(){ 

11
        public void handleMessage(Message msg) {   

12
            switch (msg.what) {   

13
            case PROGRESS_CHANGED:   

14
                setVolum();   

15
                /*sendEmptyMessageDelayed(PROGRESS_CHANGED, 200);*/

16
                break; 

17
           } 

18
        } 

19
    }; 

20
    public void onCreate(Bundle savedInstanceState) { 

21
        super.onCreate(savedInstanceState); 

22
        setContentView(R.layout.main); 

23
          
24
        volSeekBar= (SeekBar)findViewById(R.id.volum_seek); 

25
        mVolume = (TextView)findViewById(R.id.volum_val); 

26
        mAudioManager = (AudioManager)getSystemService(Context.AUDIO_SERVICE); 

27
          
28
        //setVolum(); 

29
        OnSeekBarChangeListener seekBarChangeListener = new OnSeekBarChangeListener() 

30
        { 

31
  
32
            public void onProgressChanged(SeekBar seekBar, int progress, 

33
                    boolean fromUser) { 

34
                // TODO Auto-generated method stub 

35
                mAudioManager.setStreamVolume(AudioManager.STREAM_MUSIC, progress, 0); 

36
            } 

37
  
38
            public void onStartTrackingTouch(SeekBar seekBar) { 

39
                // TODO Auto-generated method stub 

40
                  
41
            } 

42
  
43
            public void onStopTrackingTouch(SeekBar seekBar) { 

44
                // TODO Auto-generated method stub 

45
                  
46
            } 

47
              
48
        }; 

49
          
50
        volSeekBar.setOnSeekBarChangeListener(seekBarChangeListener); 

51
        new Thread(new myVolThread()).start(); 

52
          
53
    } 

54
    private void setVolum() 

55
    { 

56
          
57
        maxVolume = mAudioManager.getStreamMaxVolume(AudioManager.STREAM_MUSIC); 

58
        volSeekBar.setMax(maxVolume); 

59
        currentVolume = mAudioManager.getStreamVolume(AudioManager.STREAM_MUSIC); 

60
        volSeekBar.setProgress(currentVolume); 

61
        mVolume.setText(currentVolume*100/maxVolume + " "); 

62
    } 

63
      
64
    class myVolThread implements Runnable {    

65
        public void run() {   

66
             while (!Thread.currentThread().isInterrupted()) {     

67
                       
68
                  Message message = new Message();    

69
                  message.what =PROGRESS_CHANGED;    

70
                  MainActivity.this.myHandler.sendMessage(message);    

71
                  try {    

72
                       Thread.sleep(100);     

73
                  } catch (InterruptedException e) {    

74
                       Thread.currentThread().interrupt();    

75
                  }    

76
             }    

77
        }    

78
   }    

79
}

posted on 2011-07-19 18:52 一叶飘舟阅读(3858) 评论(0) 编辑收藏举报