Исходя из * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *}}}}}}}} * * * * * * * * * * * * * *В классе 1009 * мы видим, насколько просто прослушивать изменения громкости с помощью нашего пользовательского ContentObserver.
public class AudioFragment extends Fragment implements OnAudioVolumeChangedListener {
private AudioVolumeObserver mAudioVolumeObserver;
@Override
public void onResume() {
super.onResume();
// initialize audio observer
if (mAudioVolumeObserver == null) {
mAudioVolumeObserver = new AudioVolumeObserver(getActivity());
}
/*
* register audio observer to identify the volume changes
* of audio streams for music playback.
*
* It is also possible to listen for changes in other audio stream types:
* STREAM_RING: phone ring, STREAM_ALARM: alarms, STREAM_SYSTEM: system sounds, etc.
*/
mAudioVolumeObserver.register(AudioManager.STREAM_MUSIC, this);
}
@Override
public void onPause() {
super.onPause();
// release audio observer
if (mAudioVolumeObserver != null) {
mAudioVolumeObserver.unregister();
}
}
@Override
public void onAudioVolumeChanged(int currentVolume, int maxVolume) {
Log.d("Audio", "Volume: " + currentVolume + "/" + maxVolume);
Log.d("Audio", "Volume: " + (int) ((float) currentVolume / maxVolume) * 100 + "%");
}
}
public class AudioVolumeContentObserver extends ContentObserver {
private final OnAudioVolumeChangedListener mListener;
private final AudioManager mAudioManager;
private final int mAudioStreamType;
private int mLastVolume;
public AudioVolumeContentObserver(
@NonNull Handler handler,
@NonNull AudioManager audioManager,
int audioStreamType,
@NonNull OnAudioVolumeChangedListener listener) {
super(handler);
mAudioManager = audioManager;
mAudioStreamType = audioStreamType;
mListener = listener;
mLastVolume = audioManager.getStreamVolume(mAudioStreamType);
}
/**
* Depending on the handler this method may be executed on the UI thread
*/
@Override
public void onChange(boolean selfChange, Uri uri) {
if (mAudioManager != null && mListener != null) {
int maxVolume = mAudioManager.getStreamMaxVolume(mAudioStreamType);
int currentVolume = mAudioManager.getStreamVolume(mAudioStreamType);
if (currentVolume != mLastVolume) {
mLastVolume = currentVolume;
mListener.onAudioVolumeChanged(currentVolume, maxVolume);
}
}
}
@Override
public boolean deliverSelfNotifications() {
return super.deliverSelfNotifications();
}
}
public class AudioVolumeObserver {
private final Context mContext;
private final AudioManager mAudioManager;
private AudioVolumeContentObserver mAudioVolumeContentObserver;
public AudioVolumeObserver(@NonNull Context context) {
mContext = context;
mAudioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
}
public void register(int audioStreamType,
@NonNull OnAudioVolumeChangedListener listener) {
Handler handler = new Handler();
// with this handler AudioVolumeContentObserver#onChange()
// will be executed in the main thread
// To execute in another thread you can use a Looper
// +info: https://stackoverflow.com/a/35261443/904907
mAudioVolumeContentObserver = new AudioVolumeContentObserver(
handler,
mAudioManager,
audioStreamType,
listener);
mContext.getContentResolver().registerContentObserver(
android.provider.Settings.System.CONTENT_URI,
true,
mAudioVolumeContentObserver);
}
public void unregister() {
if (mAudioVolumeContentObserver != null) {
mContext.getContentResolver().unregisterContentObserver(mAudioVolumeContentObserver);
mAudioVolumeContentObserver = null;
}
}
}
public interface OnAudioVolumeChangedListener {
void onAudioVolumeChanged(int currentVolume, int maxVolume);
}
Надеюсь, это все еще полезно для кого-то!:)