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/* * Copyright 2002-2005 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.ServletContext; import javax.servlet.ServletException; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.struts.action.ActionServlet; import org.apache.struts.action.PlugIn; import org.apache.struts.config.ModuleConfig; import org.springframework.beans.BeanUtils; import org.springframework.beans.BeansException; import org.springframework.beans.factory.config.BeanFactoryPostProcessor; import org.springframework.beans.factory.config.ConfigurableListableBeanFactory; import org.springframework.context.ApplicationContextException; import org.springframework.context.ConfigurableApplicationContext; import org.springframework.util.ClassUtils; import org.springframework.util.StringUtils; import org.springframework.web.context.ConfigurableWebApplicationContext; import org.springframework.web.context.WebApplicationContext; import org.springframework.web.context.support.WebApplicationContextUtils; import org.springframework.web.context.support.XmlWebApplicationContext; /** * Struts 1.1+ PlugIn that loads a Spring application context for the Struts * ActionServlet. This context will automatically refer to the root * WebApplicationContext (loaded by ContextLoaderListener/Servlet) as parent. * * <p>The default namespace of the WebApplicationContext is the name of the * Struts ActionServlet, suffixed with "-servlet" (e.g. "action-servlet"). * The default location of the XmlWebApplicationContext configuration file * is therefore "/WEB-INF/action-servlet.xml". * * <pre> * <plug-in className="org.springframework.web.struts.ContextLoaderPlugIn"/></pre> * * The location of the context configuration files can be customized * through the "contextConfigLocation" setting, analogous to the root * WebApplicationContext and FrameworkServlet contexts. * * <pre> * <plug-in className="org.springframework.web.struts.ContextLoaderPlugIn"> * <set-property property="contextConfigLocation" value="/WEB-INF/action-servlet.xml /WEB-INF/myContext.xml"/> * </plug-in></pre> * * Beans defined in the ContextLoaderPlugIn context can be accessed * from conventional Struts Actions, via fetching the WebApplicationContext * reference from the ServletContext. ActionSupport and DispatchActionSupport * are pre-built convenience classes that provide easy access to the context. * * <p>It is normally preferable to access Spring's root WebApplicationContext * in such scenarios, though: A shared middle tier should be defined there * rather than in a ContextLoaderPlugin context, for access by any web component. * ActionSupport and DispatchActionSupport autodetect the root context too. * * <p>A special usage of this PlugIn is to define Struts Actions themselves * as beans, typically wiring them with middle tier components defined in the * root context. Such Actions will then be delegated to by proxy definitions * in the Struts configuration, using the DelegatingActionProxy class or * the DelegatingRequestProcessor. * * <p>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. * * <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</a>. * 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 #SERVLET_CONTEXT_PREFIX * @see ActionSupport * @see DispatchActionSupport * @see DelegatingActionProxy * @see DelegatingRequestProcessor * @see DelegatingTilesRequestProcessor * @see org.springframework.web.context.ContextLoaderListener * @see org.springframework.web.context.ContextLoaderServlet * @see org.springframework.web.servlet.FrameworkServlet */ public class ContextLoaderPlugIn implements PlugIn { /** * Suffix for WebApplicationContext namespaces. If a Struts ActionServlet is * given the name "action" in a context, the namespace used by this PlugIn will * resolve to "action-servlet". */ public static final String DEFAULT_NAMESPACE_SUFFIX = "-servlet"; /** * Default context class for ContextLoaderPlugIn. * @see org.springframework.web.context.support.XmlWebApplicationContext */ public static final Class DEFAULT_CONTEXT_CLASS = XmlWebApplicationContext.class; /** * Prefix for the ServletContext attribute for the WebApplicationContext. * The completion is the Struts module name. */ public static final String SERVLET_CONTEXT_PREFIX = ContextLoaderPlugIn.class.getName() + ".CONTEXT."; protected final Log logger = LogFactory.getLog(getClass()); /** Custom WebApplicationContext class */ private Class contextClass = DEFAULT_CONTEXT_CLASS; /** Namespace for this servlet */ private String namespace; /** Explicit context config location */ private String contextConfigLocation; /** The Struts ActionServlet that this PlugIn is registered with */ private ActionServlet actionServlet; /** The Struts ModuleConfig that this PlugIn is registered with */ private ModuleConfig moduleConfig; /** WebApplicationContext for the ActionServlet */ private WebApplicationContext webApplicationContext; /** * Set a custom context class by name. This class must be of type WebApplicationContext, * when using the default ContextLoaderPlugIn implementation, the context class * must also implement ConfigurableWebApplicationContext. * @see #createWebApplicationContext */ public void setContextClassName(String contextClassName) throws ClassNotFoundException { this.contextClass = ClassUtils.forName(contextClassName); } /** * Set a custom context class. This class must be of type WebApplicationContext, * when using the default ContextLoaderPlugIn implementation, the context class * must also implement ConfigurableWebApplicationContext. * @see #createWebApplicationContext */ public void setContextClass(Class contextClass) { this.contextClass = contextClass; } /** * Return the custom context class. */ public Class getContextClass() { return contextClass; } /** * Set a custom namespace for the ActionServlet, * to be used for building a default context config location. */ public void setNamespace(String namespace) { this.namespace = namespace; } /** * Return the namespace for the ActionServlet, falling back to default scheme if * no custom namespace was set: e.g. "test-servlet" for a servlet named "test". */ public String getNamespace() { if (this.namespace != null) { return this.namespace; } if (this.actionServlet != null) { return this.actionServlet.getServletName() + DEFAULT_NAMESPACE_SUFFIX; } return null; } /** * Set the context config location explicitly, instead of relying on the default * location built from the namespace. This location string can consist of * multiple locations separated by any number of commas and spaces. */ public void setContextConfigLocation(String contextConfigLocation) { this.contextConfigLocation = contextConfigLocation; } /** * Return the explicit context config location, if any. */ public String getContextConfigLocation() { return contextConfigLocation; } /** * Create the ActionServlet's WebApplicationContext. */ public final void init(ActionServlet actionServlet, ModuleConfig moduleConfig) throws ServletException { long startTime = System.currentTimeMillis(); if (logger.isInfoEnabled()) { logger.info("ContextLoaderPlugIn for Struts ActionServlet '" + actionServlet.getServletName() + ", module '" + moduleConfig.getPrefix() + "': initialization started"); } this.actionServlet = actionServlet; this.moduleConfig = moduleConfig; try { this.webApplicationContext = initWebApplicationContext(); onInit(); } catch (RuntimeException ex) { logger.error("Context initialization failed", ex); throw ex; } if (logger.isInfoEnabled()) { long elapsedTime = System.currentTimeMillis() - startTime; logger.info("ContextLoaderPlugIn for Struts ActionServlet '" + actionServlet.getServletName() + "', module '" + moduleConfig.getPrefix() + "': initialization completed in " + elapsedTime + " ms"); } } /** * Return the Struts ActionServlet that this PlugIn is associated with. */ public final ActionServlet getActionServlet() { return actionServlet; } /** * Return the name of the ActionServlet that this PlugIn is associated with. */ public final String getServletName() { return this.actionServlet.getServletName(); } /** * Return the ServletContext that this PlugIn is associated with. */ public final ServletContext getServletContext() { return this.actionServlet.getServletContext(); } /** * Return the Struts ModuleConfig that this PlugIn is associated with. */ public final ModuleConfig getModuleConfig() { return moduleConfig; } /** * Return the prefix of the ModuleConfig that this PlugIn is associated with. * @see org.apache.struts.config.ModuleConfig#getPrefix */ public final String getModulePrefix() { return this.moduleConfig.getPrefix(); } /** * Initialize and publish the WebApplicationContext for the ActionServlet. * Delegates to createWebApplicationContext for actual creation. * <p>Can be overridden in subclasses. Call <code>getActionServlet</code> * and/or <code>getModuleConfig</code> to access the Struts configuration * that this PlugIn is associated with. * @throws org.springframework.beans.BeansException if the context couldn't be initialized * @throws IllegalStateException if there is already a context for the Struts ActionServlet * @see #createWebApplicationContext * @see #getActionServlet * @see #getServletName * @see #getServletContext * @see #getModuleConfig * @see #getModulePrefix */ protected WebApplicationContext initWebApplicationContext() throws BeansException, IllegalStateException { getServletContext().log("Initializing WebApplicationContext for Struts ActionServlet '" + getServletName() + "', module '" + getModulePrefix() + "'"); WebApplicationContext parent = WebApplicationContextUtils.getWebApplicationContext(getServletContext()); WebApplicationContext wac = createWebApplicationContext(parent); if (logger.isInfoEnabled()) { logger.info("Using context class '" + wac.getClass().getName() + "' for servlet '" + getServletName() + "'"); } // Publish the context as a servlet context attribute. String attrName = getServletContextAttributeName(); getServletContext().setAttribute(attrName, wac); if (logger.isDebugEnabled()) { logger.debug( "Published WebApplicationContext of Struts ActionServlet '" + getServletName() + "', module '" + getModulePrefix() + "' as ServletContext attribute with name [" + attrName + "]"); } return wac; } /** * Instantiate the WebApplicationContext for the ActionServlet, either a default * XmlWebApplicationContext or a custom context class if set. This implementation * expects custom contexts to implement ConfigurableWebApplicationContext. * Can be overridden in subclasses. * @throws org.springframework.beans.BeansException if the context couldn't be initialized * @see #setContextClass * @see org.springframework.web.context.support.XmlWebApplicationContext */ protected WebApplicationContext createWebApplicationContext(WebApplicationContext parent) throws BeansException { if (logger.isDebugEnabled()) { logger.debug("ContextLoaderPlugIn for Struts ActionServlet '" + getServletName() + "', module '" + getModulePrefix() + "' will try to create custom WebApplicationContext " + "context of class '" + getContextClass().getName() + "', using parent context [" + parent + "]"); } if (!ConfigurableWebApplicationContext.class.isAssignableFrom(getContextClass())) { throw new ApplicationContextException( "Fatal initialization error in ContextLoaderPlugIn for Struts ActionServlet '" + getServletName() + "', module '" + getModulePrefix() + "': custom WebApplicationContext class [" + getContextClass().getName() + "] is not of type ConfigurableWebApplicationContext"); } ConfigurableWebApplicationContext wac = (ConfigurableWebApplicationContext) BeanUtils .instantiateClass(getContextClass()); wac.setParent(parent); wac.setServletContext(getServletContext()); wac.setNamespace(getNamespace()); if (getContextConfigLocation() != null) { wac.setConfigLocations(StringUtils.tokenizeToStringArray(getContextConfigLocation(), ConfigurableWebApplicationContext.CONFIG_LOCATION_DELIMITERS)); } wac.addBeanFactoryPostProcessor(new BeanFactoryPostProcessor() { public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) { beanFactory.addBeanPostProcessor(new ActionServletAwareProcessor(getActionServlet())); } }); wac.refresh(); return wac; } /** * Return the ServletContext attribute name for this PlugIn's WebApplicationContext. * Default implementation returns SERVLET_CONTEXT_PREFIX + module prefix. * @see #SERVLET_CONTEXT_PREFIX * @see #getModulePrefix */ public String getServletContextAttributeName() { return SERVLET_CONTEXT_PREFIX + getModulePrefix(); } /** * Return this PlugIn's WebApplicationContext. */ public final WebApplicationContext getWebApplicationContext() { return webApplicationContext; } /** * Callback for custom initialization after the context has been set up. * @throws ServletException if initialization failed */ protected void onInit() throws ServletException { } /** * Close the WebApplicationContext of the ActionServlet. * @see org.springframework.context.ConfigurableApplicationContext#close */ public void destroy() { getServletContext().log("Closing WebApplicationContext of Struts ActionServlet '" + getServletName() + "', module '" + getModulePrefix() + "'"); if (getWebApplicationContext() instanceof ConfigurableApplicationContext) { ((ConfigurableApplicationContext) getWebApplicationContext()).close(); } } }