MediaPlayer播放audio

package com.example.playaudiotest;

import java.io.File;

import android.app.Activity;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class MainActivity extends Activity implements OnClickListener {

private Button play;

private Button pause;

private Button stop;

private MediaPlayer mediaPlayer = new MediaPlayer();

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
play = (Button) findViewById(R.id.play);
pause = (Button) findViewById(R.id.pause);
stop = (Button) findViewById(R.id.stop);
play.setOnClickListener(this);
pause.setOnClickListener(this);
stop.setOnClickListener(this);
initMediaPlayer();
}

private void initMediaPlayer() {
try {
File file = new File(Environment.getExternalStorageDirectory(), "music.mp3");
mediaPlayer.setDataSource(file.getPath());
mediaPlayer.prepare();
} catch (Exception e) {
e.printStackTrace();
}
}

@Override
public void onClick(View v) {
switch (v.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.reset();
initMediaPlayer();
}
break;
default:
break;
}
}

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

}