org.springframework.web.struts
Class DelegatingActionProxy

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

public class DelegatingActionProxy
extends Action

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!

Since:

1.0.1

Author:

Juergen Hoeller

See Also:

determineActionBeanName(org.apache.struts.action.ActionMapping), DelegatingRequestProcessor, DelegatingTilesRequestProcessor, DelegatingActionUtils, ContextLoaderPlugIn

Field Summary

Fields inherited from class org.apache.struts.action.Action

defaultLocale, servlet

Constructor Summary

DelegatingActionProxy()

Method Summary

protected String	determineActionBeanName(ActionMapping mapping) Determine the name of the Action bean, to be looked up in the WebApplicationContext.
ActionForward	execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) Pass the execute call on to the Spring-managed delegate Action.
protected Action	getDelegateAction(ActionMapping mapping) Return the delegate Action for the given mapping.
protected WebApplicationContext	getWebApplicationContext(ActionServlet actionServlet, ModuleConfig moduleConfig) Fetch ContextLoaderPlugIn's WebApplicationContext from the ServletContext, falling back to the root WebApplicationContext.

Methods inherited from class org.apache.struts.action.Action

addErrors, addMessages, execute, generateToken, getDataSource, getDataSource, getErrors, getLocale, getMessages, getResources, getResources, getServlet, isCancelled, isTokenValid, isTokenValid, resetToken, saveErrors, saveErrors, saveErrors, saveMessages, saveMessages, saveToken, setLocale, setServlet

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DelegatingActionProxy

public DelegatingActionProxy()

Method Detail

execute

public ActionForward execute(ActionMapping mapping,
                             ActionForm form,
                             HttpServletRequest request,
                             HttpServletResponse response)
                      throws Exception

Pass the execute call on to the Spring-managed delegate Action.

Overrides:

execute in class Action

Throws:

Exception

See Also:

getDelegateAction(org.apache.struts.action.ActionMapping)

getDelegateAction

protected Action getDelegateAction(ActionMapping mapping)
                            throws BeansException

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.

Parameters:

mapping - the Struts ActionMapping

Returns:

the delegate Action

Throws:

BeansException - if thrown by WebApplicationContext methods

See Also:

determineActionBeanName(org.apache.struts.action.ActionMapping)

getWebApplicationContext

protected WebApplicationContext getWebApplicationContext(ActionServlet actionServlet,
                                                         ModuleConfig moduleConfig)
                                                  throws IllegalStateException

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.

Parameters:

actionServlet - the associated ActionServlet

moduleConfig - the associated ModuleConfig

Returns:

the WebApplicationContext

Throws:

IllegalStateException - if no WebApplicationContext could be found

See Also:

DelegatingActionUtils.findRequiredWebApplicationContext(org.apache.struts.action.ActionServlet, org.apache.struts.config.ModuleConfig), ContextLoaderPlugIn.SERVLET_CONTEXT_PREFIX

determineActionBeanName

protected String determineActionBeanName(ActionMapping 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.

Parameters:

mapping - the Struts ActionMapping

Returns:

the name of the Action bean

See Also:

DelegatingActionUtils.determineActionBeanName(org.apache.struts.action.ActionMapping), ActionConfig.getPath(), ModuleConfig.getPrefix()