Java tutorial
/* * Copyright 1999-2001,2004 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.webapp.example2; import java.util.Locale; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import org.apache.commons.beanutils.PropertyUtils; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.struts.action.Action; import org.apache.struts.action.ActionError; import org.apache.struts.action.ActionErrors; import org.apache.struts.action.ActionForm; import org.apache.struts.action.ActionForward; import org.apache.struts.action.ActionMapping; import org.apache.struts.util.MessageResources; import org.apache.struts.util.ModuleException; /** * Implementation of <strong>Action</strong> that validates a user logon. * * @author Craig R. McClanahan * @version $Rev: 54936 $ $Date: 2004-10-16 18:57:09 +0100 (Sat, 16 Oct 2004) $ */ public final class LogonAction extends Action { // ----------------------------------------------------- Instance Variables /** * The <code>Log</code> instance for this application. */ private Log log = LogFactory.getLog("org.apache.struts.webapp.Example"); // --------------------------------------------------------- Public Methods /** * Process the specified HTTP request, and create the corresponding HTTP * response (or forward to another web component that will create it). * Return an <code>ActionForward</code> instance describing where and how * control should be forwarded, or <code>null</code> if the response has * already been completed. * * @param mapping The ActionMapping used to select this instance * @param form The optional ActionForm bean for this request (if any) * @param request The HTTP request we are processing * @param response The HTTP response we are creating * * @exception Exception if business logic throws an exception */ public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception { // Extract attributes we will need Locale locale = getLocale(request); MessageResources messages = getResources(request); User user = null; // Validate the request parameters specified by the user ActionErrors errors = new ActionErrors(); String username = (String) PropertyUtils.getSimpleProperty(form, "username"); String password = (String) PropertyUtils.getSimpleProperty(form, "password"); UserDatabase database = (UserDatabase) servlet.getServletContext().getAttribute(Constants.DATABASE_KEY); if (database == null) errors.add(ActionErrors.GLOBAL_ERROR, new ActionError("error.database.missing")); else { user = getUser(database, username); if ((user != null) && !user.getPassword().equals(password)) user = null; if (user == null) errors.add(ActionErrors.GLOBAL_ERROR, new ActionError("error.password.mismatch")); } // Report any errors we have discovered back to the original form if (!errors.isEmpty()) { saveErrors(request, errors); return (mapping.getInputForward()); } // Save our logged-in user in the session HttpSession session = request.getSession(); session.setAttribute(Constants.USER_KEY, user); if (log.isDebugEnabled()) { log.debug("LogonAction: User '" + user.getUsername() + "' logged on in session " + session.getId()); } // Remove the obsolete form bean if (mapping.getAttribute() != null) { if ("request".equals(mapping.getScope())) request.removeAttribute(mapping.getAttribute()); else session.removeAttribute(mapping.getAttribute()); } // Forward control to the specified success URI return (mapping.findForward("success")); } // ------------------------------------------------------ Protected Methods /** * Look up the user, throwing an exception to simulate business logic * rule exceptions. * * @param database Database in which to look up the user * @param username Username specified on the logon form * * @exception AppException if a business logic rule is violated */ public User getUser(UserDatabase database, String username) throws ModuleException { // Force an ArithmeticException which can be handled explicitly if ("arithmetic".equals(username)) { throw new ArithmeticException(); } // Force an application-specific exception which can be handled if ("expired".equals(username)) { throw new ExpiredPasswordException(username); } // Look up and return the specified user return ((User) database.findUser(username)); } }