一个WEBWORK的例子

/* * $Id: RequestUtils.java 76098 2004-11-17 07:07:32Z mrdon $ * * Copyright 1999-2004 The Apache Software Foundation. * * 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.apache.struts.util; import java.net.MalformedURLException; import java.net.URL; import java.util.Collections; import java.util.Enumeration; import java.util.HashMap; import java.util.Hashtable; import java.util.Locale; import java.util.Map; import javax.servlet.ServletContext; import javax.servlet.ServletException; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpSession; import javax.servlet.jsp.JspException; import javax.servlet.jsp.PageContext; import org.apache.commons.beanutils.BeanUtils; import org.apache.commons.beanutils.DynaBean; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.struts.Globals; import org.apache.struts.action.ActionErrors; import org.apache.struts.action.ActionForm; import org.apache.struts.action.ActionMapping; import org.apache.struts.action.ActionMessages; import org.apache.struts.action.ActionServlet; import org.apache.struts.action.ActionServletWrapper; import org.apache.struts.action.DynaActionForm; import org.apache.struts.action.DynaActionFormClass; import org.apache.struts.config.ActionConfig; import org.apache.struts.config.FormBeanConfig; import org.apache.struts.config.ForwardConfig; import org.apache.struts.config.ModuleConfig; import org.apache.struts.taglib.TagUtils; import org.apache.struts.upload.MultipartRequestHandler; import org.apache.struts.upload.MultipartRequestWrapper; /** * <p>General purpose utility methods related to processing a servlet request * in the Struts controller framework.</p> * * @version $Rev: 76098 $ $Date: 2004-11-17 07:07:32 +0000 (Wed, 17 Nov 2004) $ */ public class RequestUtils { // ------------------------------------------------------- Static Variables /** * <p>Commons Logging instance.</p> */ protected static Log log = LogFactory.getLog(RequestUtils.class); // --------------------------------------------------------- Public Methods /** * <p>Create and return an absolute URL for the specified context-relative * path, based on the server and context information in the specified * request.</p> * * @param request The servlet request we are processing * @param path The context-relative path (must start with '/') * * @return absolute URL based on context-relative path * * @exception MalformedURLException if we cannot create an absolute URL */ public static URL absoluteURL(HttpServletRequest request, String path) throws MalformedURLException { return (new URL(serverURL(request), request.getContextPath() + path)); } /** * <p>Return the <code>Class</code> object for the specified fully qualified * class name, from this web application's class loader.</p> * * @param className Fully qualified class name to be loaded * @return Class object * * @exception ClassNotFoundException if the class cannot be found */ public static Class applicationClass(String className) throws ClassNotFoundException { // Look up the class loader to be used ClassLoader classLoader = Thread.currentThread().getContextClassLoader(); if (classLoader == null) { classLoader = RequestUtils.class.getClassLoader(); } // Attempt to load the specified class return (classLoader.loadClass(className)); } /** * <p>Return a new instance of the specified fully qualified class name, * after loading the class from this web application's class loader. * The specified class <strong>MUST</strong> have a public zero-arguments * constructor.</p> * * @param className Fully qualified class name to use * * @return new instance of class * @exception ClassNotFoundException if the class cannot be found * @exception IllegalAccessException if the class or its constructor * is not accessible * @exception InstantiationException if this class represents an * abstract class, an interface, an array class, a primitive type, * or void * @exception InstantiationException if this class has no * zero-arguments constructor */ public static Object applicationInstance(String className) throws ClassNotFoundException, IllegalAccessException, InstantiationException { return (applicationClass(className).newInstance()); } /** * <p>Create (if necessary) and return an <code>ActionForm</code> instance appropriate * for this request. If no <code>ActionForm</code> instance is required, return * <code>null</code>.</p> * * @param request The servlet request we are processing * @param mapping The action mapping for this request * @param moduleConfig The configuration for this module * @param servlet The action servlet * * @return ActionForm instance associated with this request */ public static ActionForm createActionForm( HttpServletRequest request, ActionMapping mapping, ModuleConfig moduleConfig, ActionServlet servlet) { // Is there a form bean associated with this mapping? String attribute = mapping.getAttribute(); if (attribute == null) { return (null); } // Look up the form bean configuration information to use String name = mapping.getName(); FormBeanConfig config = moduleConfig.findFormBeanConfig(name); if (config == null) { log.warn("No FormBeanConfig found under '" + name + "'"); return (null); } ActionForm instance = lookupActionForm(request, attribute, mapping.getScope()); // Can we recycle the existing form bean instance (if there is one)? try { if (instance != null && canReuseActionForm(instance, config)) { return (instance); } } catch(ClassNotFoundException e) { log.error(servlet.getInternal().getMessage("formBean", config.getType()), e); return (null); } return createActionForm(config, servlet); } private static ActionForm lookupActionForm(HttpServletRequest request, String attribute, String scope) { // Look up any existing form bean instance if (log.isDebugEnabled()) { log.debug( " Looking for ActionForm bean instance in scope '" + scope + "' under attribute key '" + attribute + "'"); } ActionForm instance = null; HttpSession session = null; if ("request".equals(scope)) { instance = (ActionForm) request.getAttribute(attribute); } else { session = request.getSession(); instance = (ActionForm) session.getAttribute(attribute); } return (instance); } /** * <p>Determine whether <code>instance</code> of <code>ActionForm</code> is