音频

添加权限

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

MainActivity.java

  private MediaPlayer mediaPlayer = new MediaPlayer();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button button = findViewById(R.id.play);
        Button button1 = findViewById(R.id.pause);
        Button button2 = findViewById(R.id.stop);
        button.setOnClickListener(this);
        button1.setOnClickListener(this);
        button2.setOnClickListener(this);
        //运行时权限处理
        if (ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(MainActivity.this, new String[]{
                    Manifest.permission.WRITE_EXTERNAL_STORAGE
            }, 1);
        } else {
            initMediaPlayer();//初始化MediaPlayer
        }
    }
    private void initMediaPlayer() {//用户同意授权后会调用
        try {
            File file = new File(Environment.getExternalStorageDirectory(), "music.mp3"); //SD卡根目录
            mediaPlayer.setDataSource(file.getPath()); //指定文件路径
            mediaPlayer.prepare();//让MediaPlayer进入到准备状态
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        switch (requestCode) {
            case 1:
                if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    initMediaPlayer();
                } else {
                    Toast.makeText(this, "拒绝权限将无法使用教程", Toast.LENGTH_SHORT).show();
                    finish();
                }
                break;
            default:
        }
    }
    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.play:
                if (!mediaPlayer.isPlaying()) {
                    mediaPlayer.start();
                }
                break;
            case R.id.pause:
                if (mediaPlayer.isPlaying()) {
                    mediaPlayer.pause();
                }
                break;
            case R.id.stop:
                if (mediaPlayer.isPlaying()) {
                    mediaPlayer.stop();
                    initMediaPlayer();
                }
                break;
            default:
                break;
        }
    }

    @Override
    protected void onDestroy() {//将资源释放
        super.onDestroy();
        if (mediaPlayer!=null){
            mediaPlayer.stop();
            mediaPlayer.release();
        }
    }

activity_main.xml

  <Button
        android:id="@+id/play"
        android:textAllCaps="false"
        android:text="Paly"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"></Button>
    <Button
        android:id="@+id/pause"
        android:textAllCaps="false"
        android:text="Pause"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"></Button>
    <Button
        android:id="@+id/stop"
        android:textAllCaps="false"
        android:text="Stop"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"></Button>