Why isn't my spring component accessible to the WebApplicationContext?

Question

I have a spring component which was used as a flex-blazeds endpoint (using @RemotingDestination) and I now need to reuse it as a REST endpoint.

What I did was create an additional rest servlet (of type DispatcherServlet of courser) in addition to the existing blaze-ds servlet I had.

I then wanted to access the same components using REST (hence my previous question) and I found that I'm getting a 404.

My rest-servlet.xml configuration file looked something like:

<mvc:annotation-driven />
<bean class="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping" />
<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
    <property name="messageConverters">
        <list>
            <ref bean="jsonConverter" />
        </list>
    </property>
</bean>

<bean id="jsonConverter" class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter">
    <property name="supportedMediaTypes" value="application/json" />
</bean>

And my ContextLoaderListener uses all my spring context files, which included the compontent-scan of those components.

Since the flex-servlet had no problem accessing these @Component beans which were scanned by the global context I assumed that the rest-servlet will also had access to them and I just need to add the annotations to the components.

The strange part was that when I explicitely added the component-scan for the package where these components reside then the rest call worked.

This meant that these component beans were being created twice, once for the global context (as it scans a config file containing this scan for the flex servlet) and one for the rest-servlet context (I verified this with a simple static counter and a lock on the class).

My question is why can't the rest-servlet see the beans the flex-servlet can?

Answer 1

While it's true that the servlet appcontext can access the beans from the ContextLoaderListener appcontext, those beans will not be consulted when mapping HTTP calls to controllers. All controller beans must be declared (or scanned) directly in the servlet's appcontext, else they will be ignored.

I suggest that you separate the REST entry point annotations (i.e. @RequestMapping) from your BlazeDS ones. For example, take your UserService class from your other post: create a UserController class, put the REST annotations on that, and delegate from UserController to UserService. UserController would be declared in the servlet app context, and injected with the UserService from the ContextLoaderListener context.