问如何在安卓系统中播放raw文件夹中的mp3文件作为通知声音提示

EN

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

import java.io.IOException;
import android.app.Activity;
import android.content.Context;
import android.content.SharedPreferences;
import android.content.res.AssetFileDescriptor;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.os.Vibrator;
import android.preference.PreferenceManager;
import android.util.Log;

final class BeepManager {

 private static final String TAG = BeepManager.class.getSimpleName();
 private static final float BEEP_VOLUME = 0.10f;
 private static final long VIBRATE_DURATION = 200L;
 private final Activity activity;
 private MediaPlayer mediaPlayer;
 private boolean playBeep;
 private boolean vibrate;

BeepManager(Activity activity) {
 this.activity = activity;
 this.mediaPlayer = null;
 updatePrefs();
}

void updatePrefs() {
 SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(activity);
 playBeep = shouldBeep(prefs, activity);
 vibrate = prefs.getBoolean(PreferencesActivity.KEY_VIBRATE, false);
 if (playBeep && mediaPlayer == null) {
  // The volume on STREAM_SYSTEM is not adjustable, and users found it too loud,
  // so we now play on the music stream.
   activity.setVolumeControlStream(AudioManager.STREAM_MUSIC);
   mediaPlayer = buildMediaPlayer(activity);
 }
}

void playBeepSoundAndVibrate() {
 if (playBeep && mediaPlayer != null) {
     mediaPlayer.start();
  }
  if (vibrate) {
   Vibrator vibrator = (Vibrator) activity.getSystemService(Context.VIBRATOR_SERVICE);
   vibrator.vibrate(VIBRATE_DURATION);
  }
}

 private static boolean shouldBeep(SharedPreferences prefs, Context activity) {
   boolean shouldPlayBeep = prefs.getBoolean(PreferencesActivity.KEY_PLAY_BEEP, true);
  if (shouldPlayBeep) {
    // See if sound settings overrides this
    AudioManager audioService = (AudioManager) activity.getSystemService(Context.AUDIO_SERVICE);
    if (audioService.getRingerMode() != AudioManager.RINGER_MODE_NORMAL) {
       shouldPlayBeep = false;
    }
  }
  return shouldPlayBeep;
}

private static MediaPlayer buildMediaPlayer(Context activity) {
  MediaPlayer mediaPlayer = new MediaPlayer();
  mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
  // When the beep has finished playing, rewind to queue up another one.
  mediaPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
   @Override
   public void onCompletion(MediaPlayer player) {
     player.seekTo(0);
   }
 });

 AssetFileDescriptor file = activity.getResources().openRawResourceFd(R.raw.beep);
 try {
  mediaPlayer.setDataSource(file.getFileDescriptor(), file.getStartOffset(), file.getLength());
  file.close();
  mediaPlayer.setVolume(BEEP_VOLUME, BEEP_VOLUME);
  mediaPlayer.prepare();
 } catch (IOException ioe) {
  Log.w(TAG, ioe);
  mediaPlayer = null;
 }
 return mediaPlayer;
}
}

 BeepManager beepManager = new BeepManager(this);
 beepManager.updatePrefs();



 beepManager.playBeepSoundAndVibrate();