org.springframework.web.struts.DelegatingRequestProcessor Maven / Gradle / Ivy
/*
* Copyright 2002-2006 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.web.struts;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.struts.action.Action;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.action.ActionServlet;
import org.apache.struts.action.RequestProcessor;
import org.apache.struts.config.ModuleConfig;
import org.springframework.beans.BeansException;
import org.springframework.web.context.WebApplicationContext;
/**
* 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 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 looks as follows, being able to fully leverage
* 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's 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 {@link DelegatingActionProxy DelegatingActionProxy} as Struts
* Action type in your struts-config.
*
*
The default implementation delegates to the DelegatingActionUtils
* class as fas 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.
*
* @author Juergen Hoeller
* @since 1.0.2
* @see #determineActionBeanName
* @see DelegatingTilesRequestProcessor
* @see DelegatingActionProxy
* @see DelegatingActionUtils
* @see ContextLoaderPlugIn
*/
public class DelegatingRequestProcessor extends RequestProcessor {
private WebApplicationContext webApplicationContext;
public void init(ActionServlet actionServlet, ModuleConfig moduleConfig) throws ServletException {
super.init(actionServlet, moduleConfig);
if (actionServlet != null) {
this.webApplicationContext = initWebApplicationContext(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.
* @param actionServlet the associated ActionServlet
* @param moduleConfig the associated ModuleConfig
* @return the WebApplicationContext
* @throws IllegalStateException if no WebApplicationContext could be found
* @see DelegatingActionUtils#findRequiredWebApplicationContext
* @see ContextLoaderPlugIn#SERVLET_CONTEXT_PREFIX
*/
protected WebApplicationContext initWebApplicationContext(
ActionServlet actionServlet, ModuleConfig moduleConfig) throws IllegalStateException {
return DelegatingActionUtils.findRequiredWebApplicationContext(actionServlet, moduleConfig);
}
/**
* Return the WebApplicationContext that this processor delegates to.
*/
protected final WebApplicationContext getWebApplicationContext() {
return webApplicationContext;
}
/**
* Override the base class method to return the delegate action.
* @see #getDelegateAction
*/
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);
}
/**
* 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.
* @param mapping the Struts ActionMapping
* @return the delegate Action, or null if none found
* @throws BeansException if thrown by WebApplicationContext methods
* @see #determineActionBeanName
*/
protected Action getDelegateAction(ActionMapping mapping) throws BeansException {
String beanName = determineActionBeanName(mapping);
if (!getWebApplicationContext().containsBean(beanName)) {
return null;
}
return (Action) getWebApplicationContext().getBean(beanName, Action.class);
}
/**
* 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.
* @param mapping the Struts ActionMapping
* @return the name of the Action bean
* @see DelegatingActionUtils#determineActionBeanName
* @see org.apache.struts.action.ActionMapping#getPath
* @see org.apache.struts.config.ModuleConfig#getPrefix
*/
protected String determineActionBeanName(ActionMapping mapping) {
return DelegatingActionUtils.determineActionBeanName(mapping);
}
}