org.springframework.web.struts
Class DelegatingRequestProcessor

java.lang.Object
  org.apache.struts.action.RequestProcessor
      org.springframework.web.struts.DelegatingRequestProcessor

public class DelegatingRequestProcessor
extends RequestProcessor

Subclass of Struts's default RequestProcessor that looks up Spring-managed Struts Actions defined in ContextLoaderPlugIn's WebApplicationContext (or, as a fallback, in the root WebApplicationContext).

In the Struts config file, you can either specify the original Action class (as when generated by XDoclet), or no Action class at all. In any case, Struts will delegate to an Action bean in the ContextLoaderPlugIn context.

<action path="/login" type="myapp.MyAction"/>

or

<action path="/login"/>

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(org.apache.struts.action.ActionMapping) 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 also need the Tiles setup functionality of the original TilesRequestProcessor, use DelegatingTilesRequestProcessor. As there is just a single central class to customize in Struts, we have to provide another subclass here, covering both the Tiles and the Spring delegation aspect.

If this RequestProcessor conflicts with the need for a different RequestProcessor subclass (other than TilesRequestProcessor), consider using DelegatingActionProxy as the Struts Action type in your struts-config file.

The default implementation delegates to the DelegatingActionUtils class as much as possible, to reuse as much code as possible despite the need to provide two RequestProcessor subclasses. If you need to subclass yet another RequestProcessor, take this class as a template, delegating to DelegatingActionUtils just like it.

Since:

1.0.2

Author:

Juergen Hoeller

See Also:

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

Field Summary

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

actions, INCLUDE_PATH_INFO, INCLUDE_SERVLET_PATH, log, moduleConfig, servlet

Constructor Summary

DelegatingRequestProcessor()

Method Summary

protected String	determineActionBeanName(ActionMapping mapping) Determine the name of the Action bean, to be looked up in the WebApplicationContext.
protected Action	getDelegateAction(ActionMapping mapping) Return the delegate Action for the given mapping.
protected WebApplicationContext	getWebApplicationContext() Return the WebApplicationContext that this processor delegates to.
void	init(ActionServlet actionServlet, ModuleConfig moduleConfig)
protected WebApplicationContext	initWebApplicationContext(ActionServlet actionServlet, ModuleConfig moduleConfig) Fetch ContextLoaderPlugIn's WebApplicationContext from the ServletContext, falling back to the root WebApplicationContext.
protected Action	processActionCreate(HttpServletRequest request, HttpServletResponse response, ActionMapping mapping) Override the base class method to return the delegate action.

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

destroy, doForward, doInclude, getInternal, getServletContext, internalModuleRelativeForward, internalModuleRelativeInclude, log, log, process, processActionForm, processActionPerform, processCachedMessages, processContent, processException, processForward, processForwardConfig, processInclude, processLocale, processMapping, processMultipart, processNoCache, processPath, processPopulate, processPreprocess, processRoles, processValidate

Methods inherited from class java.lang.Object

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

Constructor Detail

DelegatingRequestProcessor

public DelegatingRequestProcessor()

Method Detail

init

public void init(ActionServlet actionServlet,
                 ModuleConfig moduleConfig)
          throws ServletException

Overrides:

init in class RequestProcessor

Throws:

ServletException

initWebApplicationContext

protected WebApplicationContext initWebApplicationContext(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

getWebApplicationContext

protected final WebApplicationContext getWebApplicationContext()

Return the WebApplicationContext that this processor delegates to.

processActionCreate

protected Action processActionCreate(HttpServletRequest request,
                                     HttpServletResponse response,
                                     ActionMapping mapping)
                              throws IOException

Override the base class method to return the delegate action.

Overrides:

processActionCreate in class RequestProcessor

Throws:

IOException

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, or null if none found

Throws:

BeansException - if thrown by WebApplicationContext methods

See Also:

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

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()