Button start = (Button)findViewById(R.id.start);
Button stop = (Button)findViewById(R.id.stop);
Button.OnClickListener listener = new Button.OnClickListener(){
  @Override
  public void onClick(View v) {
    // TODO Auto-generated method stub
    Intent intent = new Intent(getApplicationContext(),MusicService.class);
    switch(v.getId()){
      case R.id.start: startService(intent);break;
      case R.id.stop: stopService(intent);break;
    }
  }
};
start.setOnClickListener(listener);
stop.setOnClickListener(listener);

public void onStart(Intent intent, int startId) {
    // TODO Auto-generated method stub
    super.onStart(intent, startId);
    Toast.makeText(this, "onStart", Toast.LENGTH_LONG).show();
    player = MediaPlayer.create(this, R.raw.eason);
    player.setLooping(true);
    player.start();
}
public void onDestroy() {
    // TODO Auto-generated method stub
    super.onDestroy();
    Toast.makeText(this, "onDestroy", Toast.LENGTH_LONG).show();
    player.stop();
}

<application
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name" >
    <activity
      android:name=".ServiceDemoActivity"
      android:label="@string/app_name" >
      <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
      </intent-filter>
    </activity>
    <service android:name="MusicService" />
</application>