Distinguish empty value from empty string ("") in Url query parameter

Question

How to distinguish URL without value like this /url?var from /url?var="" in Spring MVC?

Method HttpServletRequest::getParameterMap() in controller returns "" in both ways.

I need this to separate commands from queries to specified resource.

Answer 1

One simple way of going about doing what you want to is use the getQueryString() of HttpServletRequest. You would just check and see if the returned String contains the pattern you are looking for.

If you need something like that often (as in many controller methods) you could also easily create a custom HandlerMethodArgumentResolver that will indicate the presence of a String in the URL.

Here is the relevant Javadoc and here is an example