Proper mvc:interceptor configuration in Spring

Question

I have kind of a problem. I need to call on each request postHandle method in this interceptor:

public class DiMenuInterceptor extends HandlerInterceptorAdapter {

   @Autowired
   private IDiCategoryService categoryService;


   @Override
   public void postHandle(HttpServletRequest request,
        HttpServletResponse response, Object handler,
        ModelAndView modelAndView) throws Exception {

       modelAndView.addObject("category", categoryService.getCategoryInTree());
   }
}

so I put into servlet configuration this lines and everything work fine.

<bean class="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping" p:interceptors-ref="menuInterceptor" />

<bean id="menuInterceptor" class="cz.cosi.DiMenuInterceptor" />

But now I have to change configuration and use <mvc:interceptors>

With this configuration, I'm getting series of null pointer exception on modelAndView in the postHandle method because the postHandle method is called more than once per request.

 <mvc:interceptors>
    <bean class="cz.cosi.DiMenuInterceptor" />
 </mvc:interceptors>

With this configuration, it is working, but only for request serverAdress/anything. For request serverAdress/anything/something is postHandle not called.

<mvc:interceptors>
   <mvc:interceptor>
     <mvc:mapping path="/*" />
     <bean class="cz.cosi.DiMenuInterceptor" />
   </mvc:interceptor>
</mvc:interceptors>

part of servlet configuration

<mvc:annotation-driven />

<bean id="messageSource"
    class="org.springframework.context.support.ReloadableResourceBundleMessageSource">
    <property name="basename" value="classpath:messages" />
    <property name="defaultEncoding" value="UTF-8" />       

</bean>

<mvc:resources mapping="/css/**" location="/css/" />
<mvc:resources mapping="/images/**" location="/images/" />
<mvc:resources mapping="/js/**" location="/js/" />

<mvc:interceptors>
    <bean class="cz.cosi.DiMenuInterceptor" />
</mvc:interceptors>

<tx:jta-transaction-manager />

<tx:annotation-driven />

<bean id="transactionManager"
    class="org.springframework.orm.hibernate3.HibernateTransactionManager">
    <property name="sessionFactory" ref="sessionFactory" />
</bean>

It seems, that the problem might somehow relate to resources, because with exceptions are not properly loaded images, styles, and javascript. Without mvc:resources its working correctly, but this is not a solution.

My question is, how to properly configure DiMenuInterceptor with <mvc:interceptors>. Thanks very much for the advices.

stack:

2011-04-14 09:56:02,487 [http-8080-3] DEBUG (FilterChainProxy.java:195) ? Converted URL to lowercase, from: '/images/core/users/super_admin.png'; to: '/images/core/users/super_admin.png'
2011-04-14 09:56:02,533 [http-8080-3] DEBUG (FilterChainProxy.java:202) ? Candidate is: '/images/core/users/super_admin.png'; pattern is /images/**; matched=true
2011-04-14 09:56:02,533 [http-8080-3] DEBUG (FilterChainProxy.java:158) ? /images/core/users/super_admin.png has an empty filter list
14.4.2011 9:56:02 org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet spring threw exception
java.lang.NullPointerException
    at cz.cosi.DiMenuInterceptor.postHandle(DiMenuInterceptor.java:41)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:801)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:644)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:549)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:163)
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:237)
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:167)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    at java.lang.Thread.run(Thread.java:595)

Maybe I found a solution, but it is definitely not the best. For now it seems, that is working.

<mvc:interceptors>
    <mvc:interceptor>
        <mvc:mapping path="/*" />
        <bean class="cz.cosi.DiMenuInterceptor" />
    </mvc:interceptor>
    <mvc:interceptor>
         <mvc:mapping path="/search/**" />
        <bean class="cz.cosi.DiMenuInterceptor" />
    </mvc:interceptor>

    <mvc:interceptor>
         <mvc:mapping path="/context/**" />
        <bean class="cz.cosi.DiMenuInterceptor" />
    </mvc:interceptor>
    <mvc:interceptor>
          <mvc:mapping path="/member/**" />
        <bean class="cz.cosi.DiMenuInterceptor" />
    </mvc:interceptor>

</mvc:interceptors>

Answer 1

Your need to specify that your path includes subpaths: /**" instead /*.

<mvc:interceptors>
   <mvc:interceptor>
     <mvc:mapping path="/**" />
     <bean class="cz.cosi.DiMenuInterceptor" />
   </mvc:interceptor>
</mvc:interceptors>

@see Excample in Spring Reference, Chapter 15.12.2 mvc:interceptors