How can I tidy up this servlet parameter check code?

Question

One of the servlet in my web app takes parameters in the form www.service.com/servletname/parameter1/parameter2.

The first parameter is required and the second parameter is an integer. I've made some code to validate the parameters but it looks really really messy. Is there a nicer and cleaner way I can write the following:

Thanks :)

protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
 resp.setContentType(CONTENT_TYPE);
 PrintWriter out = resp.getWriter();
 int maximumResults = defaultMaxResults;
 // check that parameters were provided
 if (req.getPathInfo() == null)
 {
 out.println( JSONHelper.writeStatus(false, Status.TOO_FEW_ARGS.getMessage()));
 return;
 }
 // seperate parameters
 String[] parameters = req.getPathInfo().split(PARAMETER_SEPERATOR);
 if (parameters.length < MIN_NUM_PARAMETERS)
 {
 out.println( JSONHelper.writeStatus(false, Status.TOO_FEW_ARGS.getMessage()));
 return;
 }
 // validate parameters
 if (parameters.length > MIN_NUM_PARAMETERS)
 {
 try
 {
 maximumResults = Integer.parseInt(parameters[2]);
 } catch (NumberFormatException nfe)
 {
 out.println( JSONHelper.writeStatus(false, Status.INVALID_MAX_RESULTS.getMessage()));
 return;
 }
 }

Answer 1

In my opinion you could use the Regex to solve this

protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
 resp.setContentType(CONTENT_TYPE);
 PrintWriter out = resp.getWriter();
 int maximumResults = defaultMaxResults;
 // you could create pathPattern as a Class field
 Pattern pathPattern = Pattern.compile("http://www.hostname.com/servletname/([^/]+)(/(\\d+))?$");
 Matcher m = pathPattern.matcher(req.getPathInfo());
 if(m.find()) {
 String param1 = m.group(1);
 String param2 = m.group(2); // NOTE param2 may be null
 // TODO your business here
 return;
 } else {
 // TODO throw your exception here
 }
}

You can change the pathPattern to meet your need. Hope this help. Feel free to response.

• W.K.S: It's a viable solution but I'd like to quote: Some people, when confronted with a problem, think "I know, I'll use regular expressions." Now they have two problems. I think it's a little too much to check parameters.
• simpletron: That's right, but I think this regexp is simple enough for you to test, it is not a real problem here. Is your second parameter required too? If not, you can change the regexp to http://www.hostname.com/servletname/([^/]+)/(\\d+)$, you have one check now.
• W.K.S: Your code worked perfect. I used it with another page and got the regex wrong which was a bit of a hassle. In the end, I'd prefer something that's easy to read though I do think your answer is a valid way of cleaning up the code.