Android实现监听音量的变化

来源：jb51　　时间：2021/5/10 17:19:10　　对本文有异议

本文实例为大家分享了Android实现监听音量变化的具体代码，供大家参考，具体内容如下

最近项目中涉及到了音量监听然后作出改变的需求，特此mark一下

想监听音量的变化通用的就两种方法:

1、监听音量键的变化

方法： 重写 activity onKeyDown函数

@Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        switch (keyCode) {
            case KeyEvent.KEYCODE_VOLUME_UP:
                //音量键up
                return false;
            case KeyEvent.KEYCODE_VOLUME_DOWN:
                //音量键down
                return false;
            default:
                break;
        }
        return super.onKeyDown(keyCode, event);
}

优点： 快速，方便，简单

缺点：

1. 容易消耗音量键改变事件（返回false有时也没用），实测
2. 该监听针对当前Activity，不同的Ac要重新重写onKeyDown函数
3. 由第二点可知，无法做到整个应用范围监听

2、获取音量变化的广播

系统音量变化的时候会发送广播，监听这个就行，音量变化的action是
android.media.VOLUME_CHANGED_ACTION
具体的见代码：（kotlin版本）

class VolumeChangeHelper(var context: Context){
 
    private var mVolumeBroadCastReceiver: VolumeBroadCastReceiver? = null
    private var mVolumeChangeListener: VolumeChangeListener? = null
 
    companion object{
        const val  VOLUME_CHANGE_ACTION = "android.media.VOLUME_CHANGED_ACTION"
        const val EXTRA_VOLUME_STREAM_TYPE = "android.media.EXTRA_VOLUME_STREAM_TYPE"
    }
 
    private var audioManager: AudioManager? =  context.getSystemService(Context.AUDIO_SERVICE) as? AudioManager
 
    fun registerVolumeChangeListener(volumeChangeListener: VolumeChangeListener){
        mVolumeChangeListener = volumeChangeListener
        mVolumeBroadCastReceiver = VolumeBroadCastReceiver()
        val filter = IntentFilter()
        filter.addAction(VOLUME_CHANGE_ACTION)
        if(mVolumeBroadCastReceiver != null){
            //注册这个广播
            context.registerReceiver(mVolumeBroadCastReceiver!!, filter)
        }
    }
 
    fun unregisterReceiver(){
        if(mVolumeBroadCastReceiver != null){
            context.unregisterReceiver(mVolumeBroadCastReceiver!!)
            mVolumeBroadCastReceiver = null
        }
    }
 
    interface VolumeChangeListener{
        fun onVolumeDownToMin()
        fun onVolumeUp()
    }
    
    //定义一个想监听音量变化的广播接受者
    inner class VolumeBroadCastReceiver : BroadcastReceiver(){
        override fun onReceive(context: Context?, intent: Intent?) {
            if(intent?.action == VOLUME_CHANGE_ACTION && intent?.getIntExtra(EXTRA_VOLUME_STREAM_TYPE, -1) == AudioManager.STREAM_MUSIC){
                val currentVolume = audioManager?.getStreamVolume(AudioManager.STREAM_MUSIC) ?: -1
                if(currentVolume > 0){
                    mVolumeChangeListener?.onVolumeUp()
                } else  if( currentVolume == 0){
                    mVolumeChangeListener?.onVolumeDownToMin()
                }
            }
        }
 
    }
}