Android游戏开发学习笔记（二）：音频的播放(2)

import android.widget.TextView; 
 
public class MainActivity extends Activity { 
    Button btn1, btn2, btn3, btn4; 
    TextView tv; 
    MediaPlayer media; 
    SoundPool sound; 
    HashMap<Integer, Integer> soundMap; 
 
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) { 
        super.onCreate(savedInstanceState); 
        initSounds(); 
        setContentView(R.layout.main); 
        tv = (TextView) findViewById(R.id.textView); 
        btn1 = (Button) findViewById(R.id.btn1); 
        btn2 = (Button) findViewById(R.id.btn2); 
        btn3 = (Button) findViewById(R.id.btn3); 
        btn4 = (Button) findViewById(R.id.btn4); 
        btn1.setOnClickListener(btn_listener); 
        btn2.setOnClickListener(btn_listener); 
        btn3.setOnClickListener(btn_listener); 
        btn4.setOnClickListener(btn_listener); 
    } 
 
    private void initSounds() { 
        // TODO Auto-generated method stub 
        media = MediaPlayer.create(this, R.raw.shadow); 
        sound = new SoundPool(4, AudioManager.STREAM_MUSIC, 100); 
        soundMap = new HashMap<Integer, Integer>(); 
        soundMap.put(1, sound.load(this, R.raw.shake, 1)); 
    } 
 
    private OnClickListener btn_listener = new OnClickListener() { 
        @Override
        public void onClick(View v) { 
            switch (v.getId()) { 
            case R.id.btn1: 
                tv.setText("使用MediaPlayer播放声音"); 
                if (!media.isPlaying())