code: public static Long parseLong(String param) {
  		try {
  			if (!StringUtils.isBlank(param)) {
  				return Long.valueOf(param);
  			}
  		} catch (Exception e) {
  			throw new IllegalArgumentException("Parameter " + param + " is not a number.");
  		}
  		return null;
  	}
docs: 将字符串转换成Long
  @param param number string
  @return long or null if parameter is null or empty.