org.springframework.web.struts: public class: DelegatingActionProxy

org.springframework.web.struts
public class: DelegatingActionProxy [javadoc | source]

java.lang.Object
   org.apache.struts.action.Action
      org.springframework.web.struts.DelegatingActionProxy

Proxy for a Spring-managed Struts Action that is defined in ContextLoaderPlugIn's WebApplicationContext .

The proxy is defined in the Struts config file, specifying this class as the action class. This class will delegate to a Struts Action bean in the ContextLoaderPlugIn context.

<action path="/login" type="org.springframework.web.struts.DelegatingActionProxy"/>

The name of the Action bean in the WebApplicationContext will be determined from the mapping path and module prefix. This can be customized by overriding the determineActionBeanName method.

Example:

mapping path "/login" -> bean name "/login"
mapping path "/login", module prefix "/mymodule" -> bean name "/mymodule/login"

A corresponding bean definition in the ContextLoaderPlugin context would look as follows; notice that the Action is now able to leverage fully Spring's configuration facilities:

<bean name="/login" class="myapp.MyAction">
  <property name="...">...</property>
</bean>

Note that you can use a single ContextLoaderPlugIn for all Struts modules. That context can in turn be loaded from multiple XML files, for example split according to Struts modules. Alternatively, define one ContextLoaderPlugIn per Struts module, specifying appropriate "contextConfigLocation" parameters. In both cases, the Spring bean name has to include the module prefix.

If you want to avoid having to specify DelegatingActionProxy as the Action type in your struts-config file (for example to be able to generate your Struts config file with XDoclet) consider using the DelegatingRequestProcessor . The latter's disadvantage is that it might conflict with the need for a different RequestProcessor subclass.

The default implementation delegates to the DelegatingActionUtils class as much as possible, to reuse as much code as possible with DelegatingRequestProcessor and DelegatingTilesRequestProcessor .

Note: The idea of delegating to Spring-managed Struts Actions originated in Don Brown's Spring Struts Plugin. ContextLoaderPlugIn and DelegatingActionProxy constitute a clean-room implementation of the same idea, essentially superseding the original plugin. Many thanks to Don Brown and Matt Raible for the original work and for the agreement to reimplement the idea in Spring proper!

Also see:

determineActionBeanName

DelegatingRequestProcessor

DelegatingTilesRequestProcessor

DelegatingActionUtils

ContextLoaderPlugIn

author: Juergen - Hoeller

since: 1.0.1 -

Method from org.springframework.web.struts.DelegatingActionProxy Summary:
determineActionBeanName, execute, getDelegateAction, getWebApplicationContext

Methods from java.lang.Object:
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method from org.springframework.web.struts.DelegatingActionProxy Detail:
protected String determineActionBeanName(ActionMapping mapping) { return DelegatingActionUtils.determineActionBeanName(mapping); } Determine the name of the `Action` bean, to be looked up in the `WebApplicationContext`. The default implementation takes the mapping path and prepends the module prefix , if any.
public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception { Action delegateAction = getDelegateAction(mapping); return delegateAction.execute(mapping, form, request, response); } Pass the execute call on to the Spring-managed delegate `Action`.
protected Action getDelegateAction(ActionMapping mapping) throws BeansException { WebApplicationContext wac = getWebApplicationContext(getServlet(), mapping.getModuleConfig()); String beanName = determineActionBeanName(mapping); return (Action) wac.getBean(beanName, Action.class); } Return the delegate `Action` for the given `mapping`. The default implementation determines a bean name from the given `ActionMapping` and looks up the corresponding bean in the WebApplicationContext .
protected WebApplicationContext getWebApplicationContext(ActionServlet actionServlet, ModuleConfig moduleConfig) throws IllegalStateException { return DelegatingActionUtils.findRequiredWebApplicationContext(actionServlet, moduleConfig); } Fetch ContextLoaderPlugIn's WebApplicationContext from the `ServletContext`, falling back to the root `WebApplicationContext`. This context is supposed to contain the Struts `Action` beans to delegate to.

Method from org.springframework.web.struts.DelegatingActionProxy Detail:

 protected String determineActionBeanName(ActionMapping mapping) {
		return DelegatingActionUtils.determineActionBeanName(mapping);
}

Action

WebApplicationContext

The default implementation takes the mapping path and prepends the module prefix , if any.

 public ActionForward execute(ActionMapping mapping,
    ActionForm form,
    HttpServletRequest request,
    HttpServletResponse response) throws Exception {
		Action delegateAction = getDelegateAction(mapping);
		return delegateAction.execute(mapping, form, request, response);
}

Action

 protected Action getDelegateAction(ActionMapping mapping) throws BeansException {
		WebApplicationContext wac = getWebApplicationContext(getServlet(), mapping.getModuleConfig());
		String beanName = determineActionBeanName(mapping);
		return (Action) wac.getBean(beanName, Action.class);
}

Action

mapping

The default implementation determines a bean name from the given ActionMapping and looks up the corresponding bean in the WebApplicationContext .

 protected WebApplicationContext getWebApplicationContext(ActionServlet actionServlet,
    ModuleConfig moduleConfig) throws IllegalStateException {
		return DelegatingActionUtils.findRequiredWebApplicationContext(actionServlet, moduleConfig);
}

WebApplicationContext

ServletContext

WebApplicationContext

This context is supposed to contain the Struts Action beans to delegate to.