Context Hierarchy

MockDispatcher expects a WebApplicationContext (an extension of a plain ApplicationContext) for its own configuration. WebApplicationContext has a link to the MockContextImpl and the MockApi with which it is associated. It is also bound to the MockContextImpl such that applications can use static methods on RequestContextUtils to look up the WebApplicationContext if they need access to it.

For many applications, having a single WebApplicationContext is simple and suffices. It is also possible to have a context hierarchy where one root WebApplicationContext is shared across multiple MockDispatcher (or other MockApi) instances, each with its own child WebApplicationContext configuration. See Additional Capabilities of the ApplicationContext for more on the context hierarchy feature.

The root WebApplicationContext typically contains infrastructure beans, such as data repositories and business services that need to be shared across multiple MockApi instances. Those beans are effectively inherited and can be overridden (that is, re-declared) in the Servlet-specific child WebApplicationContext, which typically contains beans local to the given MockApi. The following image shows this relationship:

The following example configures a WebApplicationContext hierarchy:

Java

public class MyWebAppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {

  @Override
  protected Class<?>[] getRootConfigClasses() {
    return new Class<?>[] { RootConfig.class };
  }

  @Override
  protected Class<?>[] getServletConfigClasses() {
    return new Class<?>[] { App1Config.class };
  }

  @Override
  protected String[] getServletMappings() {
    return new String[] { "/app1/*" };
  }
}

If an application context hierarchy is not required, applications can return all configuration through getRootConfigClasses() and null from getServletConfigClasses().

The following example shows the web.xml equivalent:

<web-app>

  <listener>
    <listener-class>infra.web.context.ContextLoaderListener</listener-class>
  </listener>

  <context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>/WEB-INF/root-context.xml</param-value>
  </context-param>

  <mockApi>
    <mockApi-name>app1</mockApi-name>
    <mockApi-class>infra.web.mockApi.DispatcherServlet</mockApi-class>
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>/WEB-INF/app1-context.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
  </mockApi>

  <mockApi-mapping>
    <mockApi-name>app1</mockApi-name>
    <url-pattern>/app1/*</url-pattern>
  </mockApi-mapping>

</web-app>

If an application context hierarchy is not required, applications may configure a “root” context only and leave the contextConfigLocation Servlet parameter empty.