Android实现监听音量的变化

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时间:2021-05-10
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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()
                }
            }
        }

    }
}

想实现全局监听的话,可以在在一个app生命周期内都存在的Context里去监听,比如MainActivity

以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持。

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