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

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

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

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"/>

<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 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.

Also see:

determineActionBeanName

DelegatingTilesRequestProcessor

DelegatingActionProxy

DelegatingActionUtils

ContextLoaderPlugIn

author: Juergen - Hoeller

since: 1.0.2 -

Method from org.springframework.web.struts.DelegatingRequestProcessor Summary:
determineActionBeanName, getDelegateAction, getWebApplicationContext, init, initWebApplicationContext, processActionCreate

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

Method from org.springframework.web.struts.DelegatingRequestProcessor 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.
protected Action getDelegateAction(ActionMapping mapping) throws BeansException { String beanName = determineActionBeanName(mapping); if (!getWebApplicationContext().containsBean(beanName)) { return null; } return (Action) getWebApplicationContext().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 final WebApplicationContext getWebApplicationContext() { return this.webApplicationContext; } Return the `WebApplicationContext` that this processor delegates to.
public void init(ActionServlet actionServlet, ModuleConfig moduleConfig) throws ServletException { super.init(actionServlet, moduleConfig); if (actionServlet != null) { this.webApplicationContext = initWebApplicationContext(actionServlet, moduleConfig); } }
protected WebApplicationContext initWebApplicationContext(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.
protected Action processActionCreate(HttpServletRequest request, HttpServletResponse response, ActionMapping mapping) throws IOException { Action action = getDelegateAction(mapping); if (action != null) { return action; } return super.processActionCreate(request, response, mapping); } Override the base class method to return the delegate action.

Method from org.springframework.web.struts.DelegatingRequestProcessor 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.

 protected Action getDelegateAction(ActionMapping mapping) throws BeansException {
		String beanName = determineActionBeanName(mapping);
		if (!getWebApplicationContext().containsBean(beanName)) {
			return null;
		}
		return (Action) getWebApplicationContext().getBean(beanName, Action.class);
}

Action

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

 protected final WebApplicationContext getWebApplicationContext() {
		return this.webApplicationContext;
}

WebApplicationContext

 public  void init(ActionServlet actionServlet,
    ModuleConfig moduleConfig) throws ServletException {
		super.init(actionServlet, moduleConfig);
		if (actionServlet != null) {
			this.webApplicationContext = initWebApplicationContext(actionServlet, moduleConfig);
		}
}

 protected WebApplicationContext initWebApplicationContext(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.

 protected Action processActionCreate(HttpServletRequest request,
    HttpServletResponse response,
    ActionMapping mapping) throws IOException {
		Action action = getDelegateAction(mapping);
		if (action != null) {
			return action;
		}
		return super.processActionCreate(request, response, mapping);
}

Override the base class method to return the delegate action.