Can Spring MVC strictly map query strings to request parameters?

Question

Is there any way to configure Spring-MVC to strictly accept a known list of query strings? I'm looking to validate submitted query strings -- if a request has additional query string parameters, I'd like to know about it and return a 404.

My motivations are as follows:

Clarity: I don't want clients to fat-finger a request parameter, and still get results back (as if no request parameter was supplied)
HTTP caching: I'd like to limit the number of valid HTTP routes for my service so that HTTP caching (i.e., varnish) will work better

For example, I might have a simple controller that's configured to take one RequestParam:

@RequestMapping(value = "/selective_route", method = RequestMethod.GET) public String printTest(@RequestParam String test) { return test; }

I now want my app to accept requests and return an OK response for:

/selective_route?test=foo

But I'd want my app to notice that there are additional unaccounted request parameters, and return an ERROR response code.

/selective_route?test=foo&someotherparam=somethingelse

Seems to be a duplicate of stackoverflow.com/questions/10010176/… — John Fontaine
– John Fontaine, Commented Jul 12, 2015 at 5:31

Shepard · Accepted Answer · 2015-07-12 06:02:03Z

An interceptor can do the job. You need to implement an HandlerInterceptor and attach it to the framework. It will be called on each incoming request.

A way to perform the validation could be to keep a list of valid query strings inside the interceptor itself and check them against the incoming request, for example using regular expressions.

A faster and cleaner approach is to use a custom annotation alongside @RequestMapping. This annotation would take one parameter, again a regular expression or an array containing the names of the allowed fields.

An annotation of such kind can be declared as follows:

@Retention(RetentionPolicy.RUNTIME) @Target(ElementType.METHOD) public @interface YourAnnotationName { public String regularExpression() default ""; }

You can retrieve the method and its annotation from within the interceptor with the following code:

@Override public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { // Apply only to HandlerMethod if(!(handler instanceof HandlerMethod)) return true; // Get method and annotation instance HandlerMethod method = (HandlerMethod) handler; YourAnnotationName annotation = method.getMethodAnnotation(YourAnnotationName.class); // Method not annotated no need to evalutate if(annotation == null) return true; // Validation String queryString = request.getQueryString(); [...] }

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