Spring Framework example source code file (DelegatingActionProxy.java)

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Java - Spring Framework tags/keywords

action, action, actionforward, actionmapping, actionservlet, beansexception, delegatingactionproxy, http, httpservletresponse, illegalstateexception, moduleconfig, request, response, servlet, string, string, webapplicationcontext, webapplicationcontext

The Spring Framework DelegatingActionProxy.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 javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.action.ActionServlet;
import org.apache.struts.config.ModuleConfig;

import org.springframework.beans.BeansException;
import org.springframework.web.context.WebApplicationContext;

/**
 * Proxy for a Spring-managed Struts <code>Action that is defined in
 * {@link ContextLoaderPlugIn ContextLoaderPlugIn's}
 * {@link WebApplicationContext}.
 *
 * <p>The proxy is defined in the Struts config file, specifying this
 * class as the action class. This class will delegate to a Struts
 * <code>Action bean in the ContextLoaderPlugIn context.
 *
 * <pre class="code"><action path="/login" type="org.springframework.web.struts.DelegatingActionProxy"/>

* * 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 * <code>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 want to avoid having to specify DelegatingActionProxy * as the <code>Action type in your struts-config file (for example to * be able to generate your Struts config file with XDoclet) consider using the * {@link DelegatingRequestProcessor DelegatingRequestProcessor}. * The latter's disadvantage is that it might conflict with the need * for a different <code>RequestProcessor subclass. * * <p>The default implementation delegates to the {@link DelegatingActionUtils} * class as much as possible, to reuse as much code as possible with * <code>DelegatingRequestProcessor and * {@link DelegatingTilesRequestProcessor}. * * <p>Note: The idea of delegating to Spring-managed Struts Actions originated in * Don Brown's <a href="http://struts.sourceforge.net/struts-spring">Spring Struts Plugin. * <code>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! * * @author Juergen Hoeller * @since 1.0.1 * @see #determineActionBeanName * @see DelegatingRequestProcessor * @see DelegatingTilesRequestProcessor * @see DelegatingActionUtils * @see ContextLoaderPlugIn */ public class DelegatingActionProxy extends Action { /** * Pass the execute call on to the Spring-managed delegate <code>Action. * @see #getDelegateAction */ public ActionForward execute( ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception { Action delegateAction = getDelegateAction(mapping); return delegateAction.execute(mapping, form, request, response); } /** * 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 {@link WebApplicationContext}. * @param mapping the Struts <code>ActionMapping * @return the delegate <code>Action * @throws BeansException if thrown by <code>WebApplicationContext methods * @see #determineActionBeanName */ protected Action getDelegateAction(ActionMapping mapping) throws BeansException { WebApplicationContext wac = getWebApplicationContext(getServlet(), mapping.getModuleConfig()); String beanName = determineActionBeanName(mapping); return (Action) wac.getBean(beanName, Action.class); } /** * 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 getWebApplicationContext( ActionServlet actionServlet, ModuleConfig moduleConfig) throws IllegalStateException { return DelegatingActionUtils.findRequiredWebApplicationContext(actionServlet, moduleConfig); } /** * 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); } }