code: public static int stringToKey(String string) {
          string = Checker.checkNull(string);
          int length = string.length();
          if (length > THOUSAND) {
              return length;
          }
          int key = 0;
          for (int i = 0; i < length; i++) {
              key += (int) string.charAt(i);
          }
          return key;
      }
docs: 通过字符串获取KEY
  
  @param string 可随机一个字符串
  
  @return INT型KEY