Issue with intercepting requests to controller

Question

I want to create an abstract controller that will add the additional request mapping basen on actual mappings for the extending controller.

As an example, for the following controller

@Controller
public class MyController extends VariableResolvingController {
    @RequestMapping("page.htm") 
    public void handlerMethod() {
    }
}

I want it to extend VariableResolvingController that will add a mapping to it's resolveContextVariable(...) method with the "page.htm.context" URI.

public abstract class VariableResolvingController {
    public final @ResponseBody Object resolveContextVariable(String variableName) {
        return "{}";
    }

    protected final void registerVariableResolver(String variableName, VariableResolver resolver) {
        //...
    }
}

This approach adds a possibility to resolve custom variables using eg. AJAX requests in a way almost transparent for a client code.

Do you know any existing solutions that would be appropriate in this case?

Solution: I achieved my goal by writing a custom HandlerMapping implementation (in essence a decorator for RequestMappingHandlerMapping ).

Answer 1

One way of doing is add simple Servlet filter to your spring mvc

 public class RequestCheckFilter implements Filter {

        @Override
        public void destroy() {
            // ...
        }

        @Override
        public void init(FilterConfig filterConfig) throws ServletException         {
            //
        }

        @Override
        public void doFilter(ServletRequest request,
                   ServletResponse response, FilterChain chain)
            throws IOException, ServletException {

            try {
                HttpServletRequest httpServletRequest = ((HttpServletRequest) request);
            String requestURI = httpServletRequest.getRequestURI();

            if (requestURI.endsWith(".context")) {
                request.getRequestDispatcher(requestURI.concat(".htm"))
                    .forward(request,response);
            } else {
                chain.doFilter(httpServletRequest, response);
            }
       } catch (Exception ex) {
            request.setAttribute("errorMessage", ex);
            request.getRequestDispatcher("/WEB-INF/views/jsp/error.jsp")
                           .forward(request, response);
       }

}

add it

public class MyWebInitializer extends
        AbstractAnnotationConfigDispatcherServletInitializer {

    //...

    @Override
    protected Filter[] getServletFilters() {
        return new Filter[]{new RequestCheckFilter()};
    }
}

or in web.xml

<filter>
    <filter-name>reqHandlerFilter</filter-name>
    <filter-class>RequestCheckFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>reqHandlerFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>