code: public static int requireIntParameter (HttpServletRequest req, String name, int low, int high,
                                             String invalidDataMessage)
          throws DataValidationException
      {
          return requireIntParameter(
              req, name, invalidDataMessage, new IntRangeValidator(low, high, invalidDataMessage));
      }
docs: Fetches the supplied parameter from the request and converts it to an integer. If the
  parameter does not exist or is not a well-formed integer, a data validation exception is
  thrown with the supplied message.