code: public static int sdbmHash(String str) {
  		int hash = 0;
  
  		for (int i = 0; i < str.length(); i++) {
  			hash = str.charAt(i) + (hash << 6) + (hash << 16) - hash;
  		}
  
  		return hash & 0x7FFFFFFF;
  	}
docs: SDBM算法
  
  @param str 字符串
  @return hash值