Question

Is there a way to have a singleton resource used by multiple controllers?

We got 2 servlets, each one with its own application contexts: one-servlet.xml & two-servlet.xml and lib-context.xml with singleton bean “util”.

Now, if we import lib-context.xml into each of 2 servlet contexts above, spring will create a separate application context for each servlet and we’ll end up with 2 singletone objects.

Is there a way to configure application that only one singleton object will be created?

Answer 1

Yes. In your web.xml, load lib-context.xml with the ContextLoaderListener instead of loading it with the DispatcherServlet.

<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>
        classpath:/lib-context.xml
    </param-value>
</context-param>
<listener>
    <listener-class>
        org.springframework.web.context.ContextLoaderListener
    </listener-class>
</listener>

You can remove the imports from your servlet-specific app context configuration files.

All the DispatcherServlets will see not only the shared lib-context.xml above but also any contexts that they themselves load.

(You may need to adjust the param-value example I gave. That path is just an example.)