播放音乐

public class MainActivity extends Activity {

    private Button play,pause,stop;
    private MediaPlayer mediaPlayer = new MediaPlayer();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initMusic();
    }


    private void initMusic(){
        try{
            File file = new File(Environment.getExternalStorageDirectory()+"/Guo","a.mp3");
            mediaPlayer.setDataSource(file.getPath());
            mediaPlayer.prepare();
        }catch (Exception e){
            e.printStackTrace();
        }
    }

    protected void myClick(View v){
        if( v.getId() == R.id.play ){
            if( !mediaPlayer.isPlaying() ){
                mediaPlayer.start(); //开始播放
            }
        }

        if( v.getId() == R.id.pause ){
            if( mediaPlayer.isPlaying() ){
                mediaPlayer.pause(); // 暂停
            }
        }

        if( v.getId() == R.id.stop ){
            if( mediaPlayer.isPlaying() ){
                mediaPlayer.reset(); // 停止播放
                initMusic();
            }
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if( mediaPlayer != null  ){
            mediaPlayer.stop();
            mediaPlayer.release();
        }
    }
}

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