Re: [Springframework-developer] Proposal for Handler/Interceptor Enhancement

[Tim C. <tc...@ta...>]

I recently had a discussion about this with a friend as I ran into the 
same exact need.
I think the idea of having a separate Interceptor mapping would be a 
good idea but at the same time it would mean alot more duplication.
 From what it sounds like it would be similar to using a 
PropertiesMethodNameResolver.
 From the PetClinic example you see:

    <!--
      - This bean is a MethodNameResolver definition for a 
MultiActionController.
      - It maps URLs to methods for the "clinicController" bean.
      -->
    <bean id="clinicControllerResolver" 
class="org.springframework.web.servlet.mvc.multiaction.PropertiesMethodNameResolver">
        <property name="mappings">
        <props>
            <prop key="/welcome.htm">welcomeHandler</prop>
            <prop key="/vets.htm">vetsHandler</prop>
            <prop key="/owner.htm">ownerHandler</prop>
        </props>
        </property>
    </bean>

But yet those same urls are now duplicated in the UrlHandlerMapping:

    <!--
     - This bean is an explicit URL mapper that is used by the 
"petclinic" DispatcherServlet
     - It is used instead of the default BeanNameUrlHandlerMapping.
     -->
    <bean id="urlMapping" 
class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">
        <property name="mappings">
            <props>
                <prop key="/welcome.htm">clinicController</prop>
                <prop key="/vets.htm">clinicController</prop>
                <prop key="/owner.htm">clinicController</prop>
                <prop key="/findOwners.htm">findOwnersForm</prop>
                <prop key="/editOwner.htm">editOwnerForm</prop>
                <prop key="/addOwner.htm">addOwnerForm</prop>
                <prop key="/addVisit.htm">addVisitForm</prop>
                <prop key="/addPet.htm">addPetForm</prop>
                <prop key="/editPet.htm">editPetForm</prop>
            </props>
        </property>
    </bean>

In the example of a complex application that might have many 
URLs/Interceptor combinations you are not really going to make things 
any less complicated as you will end up having a huge amout of these. I 
wonder if an alternative approach would be to be able to attach 
interceptors directly to controllers:

    <bean id="clinicControllerResolver" 
class="org.springframework.web.servlet.mvc.multiaction.PropertiesMethodNameResolver">
        <property name="interceptors">
            <list>
                <ref bean="signonInterceptor"/>
            </list>
        </property>
        <property name="mappings">
        <props>
            <prop key="/welcome.htm">welcomeHandler</prop>
            <prop key="/vets.htm">vetsHandler</prop>
            <prop key="/owner.htm">ownerHandler</prop>
        </props>
        </property>
    </bean>

    In this way it would be very similar to the SpringAOP concept and 
removes having to find/replace all on a changed/removed URL.
It is also very easy for a maintainer to then come in and see.. oh this 
Controller has to pass thru these interceptors.

-Tim

Rod Johnson wrote:

>>The more I think about this, the more I think it will be useful.  For
>>instance, I'd like to have the OpenSessionInViewInterceptor to apply to
>>everything (/*) where other Interceptors apply to certain Controllers.
>>I'm starting to get a proliferation of UrlHandlerMapping objects just to
>>map different combinations of Interceptors.
>>
>>Jurgen, any more thoughts on this?  I might even implement this one soon
>>because it will greatly simplify things.
>>    
>>
>
>I think the proposal sounds good. I think the point about 2 types of
>interceptors is valid.
>
>
>
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