Java tutorial
/* * Copyright 1999-2002,2004 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.lang.reflect.InvocationTargetException; import java.util.Locale; import javax.servlet.ServletException; 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.ActionForm; import org.apache.struts.action.ActionForward; import org.apache.struts.action.ActionMapping; import org.apache.struts.util.MessageResources; /** * Implementation of <strong>Action</strong> that validates and creates or * updates the mail subscription entered by the user. * * @author Craig R. McClanahan * @version $Rev: 54936 $ $Date: 2004-10-16 18:57:09 +0100 (Sat, 16 Oct 2004) $ */ public final class SaveSubscriptionAction 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 the application business logic throws * an exception */ public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception { // Extract attributes and parameters we will need Locale locale = getLocale(request); MessageResources messages = getResources(request); HttpSession session = request.getSession(); SubscriptionForm subform = (SubscriptionForm) form; String action = subform.getAction(); if (action == null) { action = "?"; } if (log.isDebugEnabled()) { log.debug("SaveSubscriptionAction: Processing " + action + " action"); } // Is there a currently logged on user? User user = (User) session.getAttribute(Constants.USER_KEY); if (user == null) { if (log.isTraceEnabled()) { log.trace(" User is not logged on in session " + session.getId()); } return (mapping.findForward("logon")); } // Was this transaction cancelled? if (isCancelled(request)) { if (log.isTraceEnabled()) { log.trace(" Transaction '" + action + "' was cancelled"); } session.removeAttribute(Constants.SUBSCRIPTION_KEY); return (mapping.findForward("success")); } // Is there a related Subscription object? Subscription subscription = (Subscription) session.getAttribute(Constants.SUBSCRIPTION_KEY); if ("Create".equals(action)) { if (log.isTraceEnabled()) { log.trace(" Creating subscription for mail server '" + subform.getHost() + "'"); } subscription = user.createSubscription(subform.getHost()); } if (subscription == null) { if (log.isTraceEnabled()) { log.trace(" Missing subscription for user '" + user.getUsername() + "'"); } response.sendError(HttpServletResponse.SC_BAD_REQUEST, messages.getMessage("error.noSubscription")); return (null); } // Was this transaction a Delete? if (action.equals("Delete")) { if (log.isTraceEnabled()) { log.trace(" Deleting mail server '" + subscription.getHost() + "' for user '" + user.getUsername() + "'"); } user.removeSubscription(subscription); session.removeAttribute(Constants.SUBSCRIPTION_KEY); try { UserDatabase database = (UserDatabase) servlet.getServletContext() .getAttribute(Constants.DATABASE_KEY); database.save(); } catch (Exception e) { log.error("Database save", e); } return (mapping.findForward("success")); } // All required validations were done by the form itself // Update the persistent subscription information if (log.isTraceEnabled()) { log.trace(" Populating database from form bean"); } try { PropertyUtils.copyProperties(subscription, subform); } catch (InvocationTargetException e) { Throwable t = e.getTargetException(); if (t == null) t = e; log.error("Subscription.populate", t); throw new ServletException("Subscription.populate", t); } catch (Throwable t) { log.error("Subscription.populate", t); throw new ServletException("Subscription.populate", t); } try { UserDatabase database = (UserDatabase) servlet.getServletContext().getAttribute(Constants.DATABASE_KEY); database.save(); } catch (Exception e) { log.error("Database save", e); } // Remove the obsolete form bean and current subscription if (mapping.getAttribute() != null) { if ("request".equals(mapping.getScope())) request.removeAttribute(mapping.getAttribute()); else session.removeAttribute(mapping.getAttribute()); } session.removeAttribute(Constants.SUBSCRIPTION_KEY); // Forward control to the specified success URI if (log.isTraceEnabled()) { log.trace(" Forwarding to success page"); } return (mapping.findForward("success")); } }