任何方式来检测音量按键或音量变化与android服务？

Question

某些Android应用程序在设备的音量发生变化并且某些设备锁定音量时会生成通知。对于我的生活，我无法找到如何做到这一点。请有人帮我提供一个例子吗？

Answer 1

没有广播事件检测量的变化，但也许你可以每隔一两个秒钟检查体积就是用getStreamVolume，如果你需要在一个特定的音量锁定，每隔一两秒钟用途：setStreamVolume

有关更多信息，请检查http://developer.android.com/reference/android/media/AudioManager.htm。

您可以使用AlarmManager类或处理程序每​​隔一秒左右检查一次音量。

如果这是一项活动，您可以覆盖onKeyDown以检测按键。请参阅http://developer.android.com/reference/android/view/View.html

Answer 2

实际上，您可以使用Content Observer在服务中执行某种操作。它像一个广播接收器，听变化的内容，如音量，接触的情况下，通话记录......

使用下面的代码在服务

public class VolumeService extends Service{ 
AudioManager mAudioManager; 
Handler mHandler; 

private ContentObserver mVolumeObserver = new ContentObserver(mHandler) { 
    @Override 
    public void onChange(boolean selfChange) { 
     super.onChange(selfChange); 
     if (mAudioManager != null) { 

      final int volume = mAudioManager.getStreamVolume(AudioManager.STREAM_RING); 
      System.out.println("Volume thay đổi: " +volume); 

      Intent photoIntent = new Intent(VolumeService.this,TakePhotoActivity.class); 
      photoIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK); 
      startActivity(photoIntent); 
     } 
    } 
}; 





@Override 
public void onCreate() { 
    super.onCreate(); 

    System.out.println("Volume Service started"); 

    mAudioManager = (AudioManager) getSystemService(AUDIO_SERVICE); 

    Uri uri = Settings.System.getUriFor(Settings.System.VOLUME_SETTINGS[AudioManager.STREAM_RING]); 
    getContentResolver().registerContentObserver(uri, true, mVolumeObserver); 

    System.out.println("Đã đăng ký Volume listener"); 
} 



@Override 
public void onDestroy() { 
    super.onDestroy();  
    System.out.println("Volume service destroied"); 

    getContentResolver().unregisterContentObserver(mVolumeObserver); 
} 



@Override 
public IBinder onBind(Intent arg0) { 

    return null; 
} 

} 

不要忘了将它声明在Android Manifest.xml中

<service android:name=".service.VolumeService" > 

Answer 3

这是一种方法，您可以只修改设置的音量而不是更改。我的目标是调整系统容量服务。

此外，请避免仅在需要时进行此操作。

public class VolumeKeyController { 

    private MediaSessionCompat mMediaSession; 
    private final Context mContext; 

    public VolumeKeyController(Context context) { 
     mContext = context; 
    } 

    private void createMediaSession() { 
     mMediaSession = new MediaSessionCompat(mContext, KeyUtil.log); 

     mMediaSession.setFlags(MediaSessionCompat.FLAG_HANDLES_MEDIA_BUTTONS | 
       MediaSessionCompat.FLAG_HANDLES_TRANSPORT_CONTROLS); 
     mMediaSession.setPlaybackState(new Builder() 
       .setState(PlaybackStateCompat.STATE_PLAYING, 0, 0) 
       .build()); 
     mMediaSession.setPlaybackToRemote(getVolumeProvider()); 
     mMediaSession.setActive(true); 
    } 

    private VolumeProviderCompat getVolumeProvider() { 
     final AudioManager audio = mContext.getSystemService(Context.AUDIO_SERVICE); 

     int STREAM_TYPE = AudioManager.STREAM_MUSIC; 
     int currentVolume = audio.getStreamVolume(STREAM_TYPE); 
     int maxVolume = audio.getStreamMaxVolume(STREAM_TYPE); 
     final int VOLUME_UP = 1; 
     final int VOLUME_DOWN = -1; 

     return new VolumeProviderCompat(VolumeProviderCompat.VOLUME_CONTROL_RELATIVE, maxVolume, currentVolume) { 
      @Override 
      public void onAdjustVolume(int direction) { 
       // Up = 1, Down = -1, Release = 0 
       // Replace with your action, if you don't want to adjust system volume 
       if (direction == VOLUME_UP) { 
        audio.adjustStreamVolume(STREAM_TYPE, 
          AudioManager.ADJUST_RAISE, AudioManager.FLAG_REMOVE_SOUND_AND_VIBRATE); 
       } 
       else if (direction == VOLUME_DOWN) { 
        audio.adjustStreamVolume(STREAM_TYPE, 
          AudioManager.ADJUST_LOWER, AudioManager.FLAG_REMOVE_SOUND_AND_VIBRATE); 
       } 
       setCurrentVolume(audio.getStreamVolume(STREAM_TYPE)); 
      } 
     }; 
    } 

    // Call when control needed, add a call to constructor if needed immediately 
    public void setActive(boolean active) { 
     if (mMediaSession != null) { 
      mMediaSession.setActive(active); 
      return; 
     } 
     createMediaSession(); 
    } 

    // Call from Service's onDestroy method 
    public void destroy() { 
     if (mMediaSession != null) { 
      mMediaSession.release(); 
     } 
    } 
}