如何从Spring HandlerInterceptor中查找Handler上调用的方法？

Question

I have a Spring HandlerInterceptor intercepting the frontend URL's in my application (/app/*). I want to determine which action method in the Handler is about to be invoked from within the HandlerInterceptor. Is there a way to look that up, do I need to inject something into the interceptor that can look that up based on the requested path?

The Interceptor is like this:

public class PageCacheInterceptor implements HandlerInterceptor {...}

It is mapped like this:

<mvc:interceptors>
    <bean class="com.example.web.interceptors.PageCacheInterceptor" />
</mvc:interceptors>

Background (because I know you'll ask!). I am adding simple page caching to my app and want to use an annotation like @Cacheable on each suitable method in the controller. The interceptor can then determine whether to cache a response based on the action that created it.

For example:

@RequestMapping(value = "", method = RequestMethod.GET)
@Cacheable(events={Events.NEW_ORDER,Events.NEW_STAT})
public String home(Model model) {...}

The events are the ones that cause the cache to be invalidated. For example /widget/list action would have it's cached response invalidated by a new widget being saved.

Edit: I've upgraded to the latest Spring 3.1 M2, as this blog post hinted at features I need, but it's not clear whether injecting these new classes or sub-classing them will be required. Has any one used them to retrieve the HandlerMethod in an interceptor?

Answer 1

Ok so the solution was actually really easy:

1) Upgrade to Spring 3.1

2) RTFM (properly)

For example a HandlerInterceptor can cast the handler from Object to HandlerMethod and get access to the target controller method, its annotations, etc

3) Cast the handler object to HandlerMethod in the Interceptor.

Then you can do this sort of thing:

    HandlerMethod method = (HandlerMethod) handler;
    Cacheable methodAnnotation = method.getMethodAnnotation(Cacheable.class);
    if (methodAnnotation != null) {
        System.out.println("cacheable request");
    }

Answer 2

@Override 
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { 
System.out.println("Pre-handle"); 
HandlerMethod hm=(HandlerMethod)handler; 
Method method=hm.getMethod(); if(method.getDeclaringClass().isAnnotationPresent(Controller.class)){
 if(method.isAnnotationPresent(ApplicationAudit.class))
{ 
System.out.println(method.getAnnotation(ApplicationAudit.class).value()); 
request.setAttribute("STARTTIME",System.currentTimemillis());
 }
} 
return true; 
} 

This post has more details,hope this helps http://www.myjavarecipes.com/spring-profilingaudit-using-mvc-filters/