Spring MVC - Exclude assets from all interceptors

Question

I'm trying to figure out a way to avoid having to exclude static content from all interceptors instead of having to specify an exclude-mapping tag for each interceptor that should ignore these. Part of my context.xml is as follows:

<mvc:resources mapping="/assets/**" location="/assets/"/>

<mvc:interceptors>

    <bean class="com.myapp.security.interceptor.SecurityInterceptor" />

    <mvc:interceptor>
        <mvc:mapping path="/**" />
        <mvc:exclude-mapping path="/assets/**" />
        <bean class="com.myapp.interceptor.MessageInterceptor" />
    </mvc:interceptor>

</mvc:interceptors>

As you can see, I've specified /assets/ from being excluded from the MessageInterceptor. However, I also want SecurityInterceptor to exclude resources as well. Following DRY, it seems unreasonable to have to specify an exclude-mapping for every interceptor (since there should never really be a reason to intercept resources).

I've searched around and could not find any solutions. Any help is appreciated!

Thanks

Answer 1

I'm struggling to think of any method to achieve what you want in configuration. Perhaps someone else can offer a solution.

A quick code solution which would achieve what you want would be something like:

public abstract class ResourceExcludingHandlerInterceptor implements HandlerInterceptor
{

     @Override
     public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception
     {
          if (!isResourceHandler(handler))
          {
             doAfterCompletion(request, response, handler, ex);
          }
     }

     public abstract void doAfterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception;

     public abstract void doPostHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception;

     public abstract boolean doPreHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception;

     /**
     * <p>
         * Determine if the request is about to be handled by a mapping configured
     * by <mvc:resources>
     * </p>
     * 
     * @param handler
     *            - the handler to inspect
     * @return - true if this is a <mvc:resources> mapped request, false
     *         otherwise
     */
     private boolean isResourceHandler(Object handler)
     {
         return handler instanceof ResourceHttpRequestHandler;
     }

     @Override
     public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception
     {
         if (!isResourceHandler(handler))
         {
             doPostHandle(request, response, handler, modelAndView);
         }
     }

     @Override
     public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception
     {
         return isResourceHandler(handler) ? true : doPreHandle(request, response, handler);
     }
 }

You could then have your HandlerInterceptor implementations extend this abstract class. As <mvc:resources> is basically a short-hand way of registering ResourceHttpRequestHandler instances, this would ensure that your HandlerInterceptor implementations simply ignore any requests mapped to be handled by one.