Question

I have a Java SE application running an embedded Jetty web server hosting a RESTful web service. I want to use Spring in both the Java SE part and in the web application running in Jetty. Some beans, e.g. a dao and the entity manager, needs to be shared between the two parts. When I start the application I get duplicate versions of both the beans and the entity manager.

WARN EntityManagerFactoryRegistry.addEntityManagerFactory:80 - HHH000436: Entity manager factory name (persistenceUnit) is already registered.  If entity manager will be clustered or passivated, specify a unique value for property 'hibernate.ejb.entitymanager_factory_name'

In the Java SE part the first thing I do is to create the application context.

ApplicationContext context = new ClassPathXmlApplicationContext("classpath:server-context.xml","classpath:application-context.xml");

In the web application Spring is configured in web.xml:

<servlet>
    <servlet-name>Jersey REST Service</servlet-name>
    <servlet-class>com.sun.jersey.spi.spring.container.servlet.SpringServlet</servlet-class>
    <init-param>
        <param-name>com.sun.jersey.spi.container.ResourceFilters</param-name>
        <param-value>example.restful.server.filter.SecurityFilterFactory</param-value>
    </init-param>
    <init-param>
        <param-name>com.sun.jersey.config.property.resourceConfigClass</param-name>
        <param-value>com.sun.jersey.api.core.PackagesResourceConfig</param-value>
    </init-param>
    <init-param>
        <param-name>com.sun.jersey.config.property.packages</param-name>
        <param-value>example.restful.rest</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
</servlet>
<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>classpath:application-context.xml</param-value>
</context-param>
<listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>

How can I make the web application use the application context already created instead of duplicating all the beans?

Answer 1

I think you can create your own ContextLoaderListener and overriding createWebApplicationContext to return the ApplicationContext of your JavaSE app (assuming you have some kind of ApplicationContextHolder to keep a static access to it).

It seems easy, but you need to return a WebApplicationContext and not a ClassPathXmlApplicationContext to do this, I think you can do something like this:

public class MyContextLoaderListener extends ContextLoaderListener{
    protected WebApplicationContext createWebApplicationContext(ServletContext sc,
                                                        ApplicationContext parent){
        ApplicationContext javaSEAppContext = AppContextHolder.getAppContext();
        GenericWebApplicationContext context = new GenericWebApplicationContext(servletContext);
        context.setParent(javaSEAppContext);
        return context;
    }
}

And of course adapt your web.xml

    <!-- <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:application-context.xml</param-value>
    </context-param> -->
    <listener>
        <listener-class>com.company.MyContextLoaderListener</listener-class>
    </listener>