关于android播放sd卡中的音乐文件

            MediaPlayer mediaPlayer=new MediaPlayer();
    //申请两个权限
    if(ContextCompat.checkSelfPermission(this, android.Manifest.permission.WRITE_EXTERNAL_STORAGE)
            != PackageManager.PERMISSION_GRANTED){
        requestPermissions(new String[]{android.Manifest.permission.WRITE_EXTERNAL_STORAGE},100);
    }
    if(ContextCompat.checkSelfPermission(this, android.Manifest.permission.MOUNT_UNMOUNT_FILESYSTEMS)!= PackageManager.PERMISSION_GRANTED){
        requestPermissions(new String[]{android.Manifest.permission.MOUNT_UNMOUNT_FILESYSTEMS},200);
    }


    try {
            //设置文件路径
        mediaPlayer.setDataSource(Environment.getExternalStorageDirectory().getPath()
                + File.separator+"music.mp3");
        mediaPlayer.prepare();
        mediaPlayer.start();
    } catch (IOException e) {
        System.out.println("错误");
        e.printStackTrace();
    }

试着打印一下那个文件路径，估计文件路径出错！其实可以通过日志打印看出是哪行代码出的问题和到底报什么错误的！