code: private void init() {
          if (soundPool == null)
              soundPool = new SoundPool(256, AudioManager.STREAM_MUSIC, 100);
  
          synchronized (locker) {
              if (soundMap != null) {
                  soundMap.clear();
              } else {
                  soundMap = new HashMap<Integer, Integer>();
              }
          }
      }
docs: 初始化音效播放器