Question

某些Android应用会在设备的音量发生变化时生成通知，有些会锁定音量。对于我的生活，我不知道如何做到这一点。请有人帮我提供一个例子吗？

Answer 1

没有广播操作可以检测音量变化，但您可能每隔一两次检查音量与getStreamVolume的关系，如果需要将其锁定在特定音量，则每隔一两次使用： setStreamVolume

查看http://developer.android.com/reference/android/media/AudioManager.htm了解详情。

您可以使用AlarmManager类或处理程序每秒检查一次音量。

如果是活动，您可以覆盖onKeyDown以检测按键操作。见http://developer.android.com/reference/android/view/View.html

Answer 2

实际上，通过使用内容观察器，您可以通过一种方式进行服务。它就像一个广播接收器，听取音量，联系人，通话记录等内容变化的事件......

在您的服务中使用以下代码

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;
}

}

不要忘记在Android Manifest.xml中声明它

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

Answer 3

这是一种方法，你可以修复设定的音量而不是改变。我的目标是调整系统服务量。

另外，请避免在需要时这样做。

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();
        }
    }
}

Answer 4

您可以使用辅助功能捕获音量/硬件按键事件。

How to capture key events inside a service?

用android服务检测音量键按下或音量变化的任何方法？

4 个答案: