如何检测android中的音量变化？

Question

你们很多人可能都知道，Android 有许多卷流，例如：

STREAM_ALARM        The audio stream for alarms
STREAM_DTMF         The audio stream for DTMF Tones
STREAM_MUSIC        The audio stream for music playback
STREAM_NOTIFICATION The audio stream for notifications
STREAM_RING         The audio stream for the phone ring
STREAM_SYSTEM       The audio stream for system sounds
STREAM_VOICE_CALL   The audio stream for phone calls

我一直在使用内容观察者。到目前为止，我可以检测一个卷流的变化，但我想知道如何检测上述任何流的变化。我遵循了这个答案中的方法https://stackoverflow.com/a/15292255/2433261

编辑：在将此问题标记为重复之前，请注意，我想检测是否有任何体积流的幅度发生变化。

Answer 1

每当任何流上的音量发生变化时，此流程都会为您提供一个布尔值：

val Context.volumeFlow
    get() = callbackFlow {
        val receiver = object : BroadcastReceiver() {
            override fun onReceive(context: Context, intent: Intent) {
                val newVolume = intent.getIntExtra(
                    "android.media.EXTRA_VOLUME_STREAM_VALUE",
                    0
                )

                val prevVolume = intent.getIntExtra(
                    "android.media.EXTRA_PREV_VOLUME_STREAM_VALUE",
                    0
                )

                // You can also obtain the type if needed.
                // val type = intent.getIntExtra("android.media.EXTRA_VOLUME_STREAM_TYPE", 0)
                trySend(newVolume != prevVolume)
            }
        }

        registerReceiver(receiver, IntentFilter("android.media.VOLUME_CHANGED_ACTION"))
        awaitClose { unregisterReceiver(receiver) }
    }

然后您可以从

ContextWrapper

（例如，

Activity

、

Service

）中使用它，如下所示：

lifecycleScope.launch { 
    volumeFlow.collect { Log.d("SOME TAG", "Volume changed: $it") }
}