private fun listRaw() {
    val fields: Array<Field> = R.raw::class.java.fields
    for (count in fields.indices) {
        val resourceID = fields[count].getInt(fields[count])
    }
}

上面的代码可以用来列出raw文件夹中的所有文件，并使用资源ID在媒体播放器中播放它们。

mediaPlayer = MediaPlayer.create(this,resourceID)

resourceID将与R.raw.sampl相同
对于活动到服务的通信，建议使用绑定器。观看此video以更好地了解服务。
MyService类

class MyService : Service() {

    private val binder = MyServiceBinder()

    override fun onBind(intent: Intent): IBinder {
        return binder
    }

    fun playMusic(ab: Int) {
        val mediaPlayer = MediaPlayer.create(this,ab)
        mediaPlayer.start()
    }

    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
        return START_STICKY
    }

    inner class MyServiceBinder : Binder(){
        fun getService() = this@MyService
    }
}

而在活动中

private lateinit var myService: MyService
private val connection = object : ServiceConnection{
    override fun onServiceConnected(p0: ComponentName?, p1: IBinder?) {
        val binder = p1 as MyService.MyServiceBinder
        myService = binder.getService()
    }

    override fun onServiceDisconnected(p0: ComponentName?) {

    }

}

override fun onStart() {
    super.onStart()
    Intent(this,MyService::class.java).also{
        bindService(it,connection,Context.BIND_AUTO_CREATE)
        startService(it)
    }
}

override fun onStop() {
    super.onStop()
    unbindService(connection)
}

和按钮点击或每当你想播放音乐。使用resourceID代替R.raw.ab

if (::myService.isInitialized) {
                myService.playMusic(R.raw.ab)
            }

你可以通过Intent将你的原始资源ID传递给你的服务：

binding.btnPlay.setOnClickListener {
    val intent = Intent(requireContext(), MusicService::class.java)
    intent.putExtra("playSong", R.raw.sampl)
    intent.action = MusicService.ACTION_PLAY
    requireActivity().startService(intent)
}

然后，在服务中获取您的资源ID：

override fun onStartCommand(intent: Intent, flags: Int, startId: Int): Int {
   super.onStartCommand(intent, flags, startId)

   if (intent != null && intent.extras != null) {
      val songResId = intent.getIntExtra("playSong", -1)
    
      if (songResId != -1) {
         //play song
      }