有没有办法在Android上监听音量变化的事件,而不只是接管音量按钮?
我发现唯一有效的是这里,但它只有在音量控制消失后才有效。
并非所有设备都有音量按钮,我需要在音量变化发生时立即捕获它们,而不是在音量对话框消失后捕获。
更好的是,您可以按如下方式注册
ContentObserver
:
getApplicationContext().getContentResolver().registerContentObserver(android.provider.Settings.System.CONTENT_URI, true, new ContentObserver(){...} );
您的 ContentObserver 可能如下所示:
public class SettingsContentObserver extends ContentObserver {
private AudioManager audioManager;
public SettingsContentObserver(Context context, Handler handler) {
super(handler);
audioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
}
@Override
public boolean deliverSelfNotifications() {
return false;
}
@Override
public void onChange(boolean selfChange) {
int currentVolume = audioManager.getStreamVolume(AudioManager.STREAM_MUSIC);
Log.d(TAG, "Volume now " + currentVolume);
}
}
完成后:
getApplicationContext().getContentResolver().unregisterContentObserver(mContentObserver);
但需要注意的是 - 有时,如果快速按下大量按钮,通知似乎会延迟。
好吧,现在,我所做的是使用 onKeyDown 监听音量按钮(并检查 KEYCODE_VOLUME_DOWN、KEYCODE_VOLUME_MUTE、KEYCODE_VOLUME_UP ),并使用我发布的新的可运行程序来检查音量级别。
另外,由于某些设备有音量对话框,因此我根据此链接添加了一个侦听器来监听它何时消失。
使用广播接收器VOLUME_CHANGED_ACTION,然后使用AudioManager获取当前音量。
<receiver android:name="VolumeChangeReceiver" >
<intent-filter>
<action android:name="android.media.VOLUME_CHANGED_ACTION" />
</intent-filter>
</receiver>
可与音量按钮和 Android 系统 UI 配合使用。 在本例中,我使用 BroadcastReceiver 作为 Inner Class。 我正在使用与此类似的实现来更新片段中的搜索栏。
public class AFragment extends Fragment {
private Context context;
private AudioManager audioManager;
// THE STREAM TYPE YOU WANT VOLUME FROM
private final int streamType = AudioManager.STREAM_MUSIC;
private VolumeChangeListener volumeChangeListener;
private IntentFilter intentFilter;
private final String VOLUME_CHANGED_ACTION = "android.media.VOLUME_CHANGED_ACTION";
public AFragment(Context context) {
this.context = context;
this.audioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
this.volumeChangeListener = new VolumeChangeListener();
this.intentFilter = new IntentFilter(VOLUME_CHANGED_ACTION);
}
@Override
public void onDestroy() {
super.onDestroy();
context.unregisterReceiver(volumeChangeListener);
}
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
context.registerReceiver(volumeChangeListener, intentFilter);
}
private class VolumeChangeListener extends BroadcastReceiver {
// VOLUME CHANGED ACTION triggers 3 times
// Making use of increment variable to make sure to skip the extra calls
private int callCount = 0;
@Override
public void onReceive(Context context, Intent intent) {
callCount++;
if (intent.getAction().equals(VOLUME_CHANGED_ACTION)) {
if (callCount % 3 == 0) {
int SYSTEM_currentVolume = audioManager.getStreamVolume(streamType);
// DO WHATEVER YOU WANT WITH THE NEW VOLUME VALUE
}
}
}
}
}
IntentFilter android.media.VOLUME_CHANGED_ACTION可以在这里找到:Android Google Source
您可以使用: 注册MediaButtonEventReceiver(组件名称事件接收器) 它将组件注册为 MEDIA_BUTTON 意图的唯一接收者。
// in your activity.
MediaButtonReceiver receiver = new MediaButtonReceiver();
// in onCreate put
registerMediaButtonEventReceiver(receiver);
class MediaButtonReceiver implements BroadcastReceiver {
void onReceive(Intent intent) {
KeyEvent ke = (KeyEvent)intent.getExtra(Intent.EXTRA_KEY_EVENT);
if (ke .getKeyCode() == KeyEvent.KEYCODE_VOLUME_DOWN) {
//action when volume goes down
}
if (ke .getKeyCode() == KeyEvent.KEYCODE_VOLUME_UP) {
//action when volume goes up
}
}
}
//In both onStop and onPause put :
unregisterMediaButtonEventReceiver(receiver);
我们在这里所做的是定义一个处理 ACTION_MEDIA_BUTTON 的 BroadcastReceiver。并使用 EXTRA_KEY_EVENT ,它包含导致广播获取按下的内容并对其采取行动的按键事件。
对于使用 kotlin 流的用户,您可以使用以下方法来监听特定流的音量变化(本例中为通知):
private val Context.notificationVolumeFlow
get() = callbackFlow {
val receiver = object : BroadcastReceiver() {
override fun onReceive(context: Context, intent: Intent) {
when (intent.getIntExtra("android.media.EXTRA_VOLUME_STREAM_TYPE", 0)) {
AudioManager.STREAM_NOTIFICATION -> trySend(
intent.getIntExtra(
"android.media.EXTRA_VOLUME_STREAM_VALUE",
0
)
)
}
}
}
registerReceiver(receiver, IntentFilter("android.media.VOLUME_CHANGED_ACTION"))
awaitClose { unregisterReceiver(receiver) }
}
您可以按照以下方式领取:
lifecycleScope.launch {
notificationVolumeFlow.collect { Log.d("SOME_TAG", "Notification stream volume: $it") }
}