Servlet Web Application Context from filter - spring

Question

I try to get the spring web application context from a filter.
I was previously getting it through:
WebApplicationContextUtils.getRequiredWebApplicationContext(request.getServletContext())
It was ok, because I was getting what is called I think the ROOT web application context.
Now, I wanted to move all my spring definition like that in web.xml :
<servlet>
<servlet-name>dispatcher</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<!-- Configure DispatcherServlet to use AnnotationConfigWebApplicationContext instead of default XmlWebApplicationContext. -->
<init-param>
<param-name>contextClass</param-name>
<param-value>org.springframework.web.context.support.AnnotationConfigWebApplicationContext</param-value>
</init-param>
<!-- Custom web configuration annotated class. -->
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>foo.bar.WebConfiguration</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
I removed the "old" definition from web.xml :
<!-- <context-param> -->
<!-- <param-name>contextConfigLocation</param-name> -->
<!-- <param-value>/WEB-INF/dispatcher-servlet.xml</param-value> -->
<!-- </context-param> -->
<!-- <listener> -->
<!-- <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> -->
<!-- </listener> -->
Now, I have no more "ROOT" web application context, and the filter cannot get the another web application context.
I saw that there is another call :
WebApplicationContextUtils.getWebApplicationContext(sc, attrName)
it allows to specify as second argument the "attribute", it is in fact the web application context you want.By default, it is "org.springframework.web.context.WebApplicationContext.ROOT".
I think I have to call this method but I don't know what to put as second parameter.
PS : I also tried to use org.springframework.web.filter.DelegatingFilterProxy, but tomcat throwed the error that he dont find the classic (ROOT) web application context :
java.lang.IllegalStateException: No WebApplicationContext found: no ContextLoaderListener registered?
BUT THERE IS ANOTHER CONTEXT, it is just defined in another way. It is not possible I am the only one trying to get another context that the ROOT.
Thanks to have read so far.

Answer 1

I just read your answer, and yes I figured it out yesterday night ;-)
I added the ROOT context, defining it like that:
<context-param>
<param-name>contextClass</param-name>
<param-value>org.springframework.web.context.support.AnnotationConfigWebApplicationContext</param-value>
</context-param>
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>foo.bar.WebConfiguration</param-value>
</context-param>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
And its working, the filter can acces to the service directly with Autowiring.
I still have the feeling that my architecture is dirty because the ROOT and "dispatcher" context are the same, I think it's not a good practice.
Maybe I'll try later to split the "WebConfiguration" in two.
Thank you anyway!