code: public static int intHash(int key) {
  		key += ~(key << 15);
  		key ^= (key >>> 10);
  		key += (key << 3);
  		key ^= (key >>> 6);
  		key += ~(key << 11);
  		key ^= (key >>> 16);
  		return key;
  	}
docs: Thomas Wang的算法，整数hash
  
  @param key 整数
  @return hash值