最近接收公司的IM项目，遇到一个历史遗留下来的问题（三星手机在语音消息播放时手机音量键无法控制声音的大小）。由于第一次接触音频类的东西。在这方面经验还是有些不足。在寻找这个问题的解决方案时，也是浪费了不少时间。在此记录一下。希望可以帮助到有相同问题的小伙伴。
1、经测试对比同行软件：三星手机的音频播放音量是由媒体音量控制，不管是外放还是听筒模式。（这里项目是由MediaPlayer进行播放的）

2、解决思路：1.通过监听手机侧键，手动更改媒体音量。2.通过注册广播监听手机音量的改变，更改媒体音量。

具体代码如下：（伸手党福利）

第一种方案：

    private lateinit var audioManager: AudioManager
    private var mMusicMaxVolume = 0 //手机设置的最大媒体音量
    private var mVoiceCallMaxVolume = 0//手机设置的最大通话音量
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)  
        setContentView(R.layout.activity_main)
        audioManager = getSystemService(Context.AUDIO_SERVICE) as AudioManager
        mVoiceCallMaxVolume = audioManager.getStreamMaxVolume(AudioManager.STREAM_VOICE_CALL)
        mMusicMaxVolume = audioManager.getStreamMaxVolume(AudioManager.STREAM_MUSIC)
    }

   override fun onKeyDown(keyCode: Int, event: KeyEvent?): Boolean {
        //如果是三星手机，则听筒模式音量设置要设置媒体音量（加上判断三星手机代码逻辑较严谨）
        if (audioManager.mode == AudioManager.MODE_IN_COMMUNICATION && !audioManager.isSpeakerphoneOn && (keyCode == KeyEvent.KEYCODE_VOLUME_UP || keyCode == KeyEvent.KEYCODE_VOLUME_DOWN)) {
            //当前通话音量
            val mCurrentVoiceCallVolume =
                audioManager.getStreamVolume(AudioManager.STREAM_VOICE_CALL)
            //计算出当前媒体音量
            val mCurrentMusicVolume =
                mCurrentVoiceCallVolume * mMusicMaxVolume / mVoiceCallMaxVolume
            Log.e(
                "TAG",
                "currentVolume=" + mCurrentMusicVolume + "mMusicMaxVolume=" + mMusicMaxVolume
            )
            audioManager.setStreamVolume(
                AudioManager.STREAM_MUSIC,
                mCurrentMusicVolume,
                AudioManager.USE_DEFAULT_STREAM_TYPE
            )
        }
        return super.onKeyDown(keyCode, event)
    }

第二种方案：

private lateinit var volumeBroadCastReceiver: SamsungVolumeBroadCastReceiver
override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
         volumeBroadCastReceiver = SamsungVolumeBroadCastReceiver()
         registerReceiver(
            volumeBroadCastReceiver ,
            IntentFilter(SamsungVolumeBroadCastReceiver.Action)
        )
}

    override fun onDestroy() {
        super.onDestroy()
        unregisterReceiver(volumeBroadCastReceiver)
    }

class SamsungVolumeBroadCastReceiver : BroadcastReceiver() {
    companion object {
        const val Action = "android.media.VOLUME_CHANGED_ACTION"
    }

    private var audioManager: AudioManager =
        App.instance.getSystemService(Context.AUDIO_SERVICE) as AudioManager
    private var mVoiceCallMaxVolume = 0
    private var mMusicMaxVolume = 0

    init {
        mVoiceCallMaxVolume =
            audioManager.getStreamMaxVolume(AudioManager.STREAM_VOICE_CALL)
        mMusicMaxVolume = audioManager.getStreamMaxVolume(AudioManager.STREAM_MUSIC)
    }

    override fun onReceive(content: Context?, intent: Intent?) {
        //改变的类型
        val mVolumeType = intent?.getIntExtra(
            "android.media.EXTRA_VOLUME_STREAM_TYPE",
            -1
        )
        //当前改变的值
        val mNewVolume = intent?.getIntExtra(
            "android.media.EXTRA_VOLUME_STREAM_VALUE",
            -1
        ) ?: -1
        //改变前的值
        val mOldVolume = intent?.getIntExtra(
            "android.media.EXTRA_PREV_VOLUME_STREAM_VALUE",
            -1
        )
       //一次音量改变会接收到两次action,这里判断一下mNewVolume和mOldVolume
        if (intent?.action == Action && mVolumeType == AudioManager.STREAM_VOICE_CALL && !audioManager.isSpeakerphoneOn && (mNewVolume != mOldVolume)
        ) {
            val mCurrentMusicVolume =
                mNewVolume * mMusicMaxVolume / mVoiceCallMaxVolume
            //记录一下 怕有计算出来的mCurrentMusicVolume大于最大值导致的异常奔溃情况
            mLog.e(
                "SamsungVolumeBroadCast",
                "currentVolume=${mCurrentMusicVolume},mMusicMaxVolume=${mMusicMaxVolume}"
            )
            audioManager.setStreamVolume(
                AudioManager.STREAM_MUSIC,
                mCurrentMusicVolume,
                AudioManager.USE_DEFAULT_STREAM_TYPE
            )
        }
    }
}

还有注意的是切换听筒模式的时候记得设置下媒体音量，以免一开始无声

            audioManager.isSpeakerphoneOn = false //关闭扬声器
            audioManager.mode = AudioManager.MODE_IN_COMMUNICATION
            //三星手机听筒模式要设置媒体音量
            if (SystemUtil.isSamsung()) {
                audioManager.setStreamVolume(
                    AudioManager.STREAM_MUSIC,
                    audioManager.getStreamMaxVolume(AudioManager.STREAM_MUSIC),
                    AudioManager.USE_DEFAULT_STREAM_TYPE
                )
            }
            audioManager.setStreamVolume(
                AudioManager.STREAM_VOICE_CALL,
                audioManager.getStreamMaxVolume(AudioManager.STREAM_VOICE_CALL),
                AudioManager.USE_DEFAULT_STREAM_TYPE
            )