音乐播放器及各种功能

public class Main2Activity extends AppCompatActivity {
    private Button btn;
    private MediaPlayer player;
    private Button stop;
    private Button puase;
    private Button restart;
    private SeekBar sb;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
        btn = (Button) findViewById(R.id.btn);
        stop = (Button) findViewById(R.id.stop);
        restart = (Button) findViewById(R.id.restart);
        sb = (SeekBar) findViewById(R.id.sb);
        restart.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                player.start();
            }
        });
        stop.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(player.isPlaying()){
                    player.stop();
                }
            }
        });
        puase = (Button) findViewById(R.id.puase);
        puase.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(player.isPlaying()){
                    player.pause();
                }
            }
        });
        player = new MediaPlayer();
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                try {
                    player.reset();
                    player.setDataSource("http://www.ytmp3.cn/down/43210.mp3");
// player.prepare();
                    player.prepareAsync();
                    player.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
                        @Override
                        public void onPrepared(MediaPlayer mp) {
                            player.start();
                        }
                    });

                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        });
        sb.setMax(player.getDuration());
        sb.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
            @Override
            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
                if(fromUser){
                    player.seekTo(progress);
                }
            }

            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {

            }

            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {

            }
        });
        Timer timer = new Timer();
        timer.schedule(new TimerTask() {
            @Override
            public void run() {
                sb.setProgress(player.getCurrentPosition());
            }
        },0,1000);
    }

}