Spring Framework example source code file (DelegatingRequestProcessor.java)

This example Spring Framework source code file (DelegatingRequestProcessor.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Spring Framework tags/keywords

action, action, actionmapping, delegatingrequestprocessor, http, illegalstateexception, io, ioexception, moduleconfig, moduleconfig, request, requestprocessor, response, servlet, servletexception, string, string, webapplicationcontext, webapplicationcontext

The Spring Framework DelegatingRequestProcessor.java source code

/*
 * Copyright 2002-2007 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 {@link RequestProcessor} that looks up
 * Spring-managed Struts {@link Action Actions} defined in
 * {@link ContextLoaderPlugIn ContextLoaderPlugIn's} {@link WebApplicationContext}
 * (or, as a fallback, in the root <code>WebApplicationContext).
 *
 * <p>In the Struts config file, you can either specify the original
 * <code>Action class (as when generated by XDoclet), or no
 * <code>Action class at all. In any case, Struts will delegate to an
 * <code>Action bean in the ContextLoaderPlugIn context.
 *
 * <pre class="code"><action path="/login" type="myapp.MyAction"/>

* * or * * <pre class="code"><action path="/login"/> * * The name of the <code>Action bean in the * <code>WebApplicationContext will be determined from the mapping path * and module prefix. This can be customized by overriding the * {@link #determineActionBeanName} method. * * <p>Example: * <ul> * <li>mapping path "/login" -> bean name "/login"
* <li>mapping path "/login", module prefix "/mymodule" -> * bean name "/mymodule/login" * </ul> * * <p>A corresponding bean definition in the ContextLoaderPlugin * context would look as follows; notice that the <code>Action is now * able to leverage fully Spring's configuration facilities: * * <pre class="code"> * <bean name="/login" class="myapp.MyAction"> * <property name="...">...</property> * </bean></pre> * * Note that you can use a single <code>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 * <code>ContextLoaderPlugIn per Struts module, specifying appropriate * "contextConfigLocation" parameters. In both cases, the Spring bean name has * to include the module prefix. * * <p>If you also need the Tiles setup functionality of the original * <code>TilesRequestProcessor, use * <code>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. * * <p>If this RequestProcessor conflicts with the need for a * different <code>RequestProcessor subclass (other than * <code>TilesRequestProcessor), consider using * {@link DelegatingActionProxy} as the Struts <code>Action type in * your struts-config file. * * <p>The default implementation delegates to the * <code>DelegatingActionUtils class as much as possible, to reuse as * much code as possible despite the need to provide two * <code>RequestProcessor subclasses. If you need to subclass yet * another <code>RequestProcessor, take this class as a template, * delegating to <code>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 {@link WebApplicationContext} from the * <code>ServletContext, falling back to the root * <code>WebApplicationContext. * <p>This context is supposed to contain the Struts Action * beans to delegate to. * @param actionServlet the associated <code>ActionServlet * @param moduleConfig the associated <code>ModuleConfig * @return the <code>WebApplicationContext * @throws IllegalStateException if no <code>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 <code>WebApplicationContext that this processor * delegates to. */ protected final WebApplicationContext getWebApplicationContext() { return this.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 <code>Action for the given mapping. * <p>The default implementation determines a bean name from the * given <code>ActionMapping and looks up the corresponding * bean in the <code>WebApplicationContext. * @param mapping the Struts <code>ActionMapping * @return the delegate <code>Action, or null if none found * @throws BeansException if thrown by <code>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 <code>Action bean, to be looked up in * the <code>WebApplicationContext. * <p>The default implementation takes the * {@link org.apache.struts.action.ActionMapping#getPath mapping path} and * prepends the * {@link org.apache.struts.config.ModuleConfig#getPrefix module prefix}, * if any. * @param mapping the Struts <code>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); } }