1 /*
2 * $Id: SwitchAction.java 471754 2006-11-06 14:55:09Z husted $
3 *
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21 package org.apache.struts.actions;
22
23 import org.apache.commons.logging.Log;
24 import org.apache.commons.logging.LogFactory;
25 import org.apache.struts.Globals;
26 import org.apache.struts.action.ActionForm;
27 import org.apache.struts.action.ActionForward;
28 import org.apache.struts.action.ActionMapping;
29 import org.apache.struts.util.ModuleUtils;
30
31 import javax.servlet.ServletException;
32 import javax.servlet.http.HttpServletRequest;
33 import javax.servlet.http.HttpServletResponse;
34
35 /**
36 * <p>A standard <strong>Action</strong> that switches to a new module and
37 * then forwards control to a URI (specified in a number of possible ways)
38 * within the new module.</p>
39 *
40 * <p>Valid request parameters for this Action are:</p>
41 *
42 * <ul>
43 *
44 * <li><strong>page</strong> - Module-relative URI (beginning with "/") to
45 * which control should be forwarded after switching.</li>
46 *
47 * <li><strong>prefix</strong> - The module prefix (beginning with "/") of the
48 * module to which control should be switched. Use a zero-length string for
49 * the default module. The appropriate <code>ModuleConfig</code> object will
50 * be stored as a request attribute, so any subsequent logic will assume the
51 * new module.</li>
52 *
53 * </ul>
54 *
55 * @version $Rev: 471754 $ $Date: 2005-05-14 21:27:02 -0400 (Sat, 14 May 2005)
56 * $
57 * @since Struts 1.1
58 */
59 public class SwitchAction extends BaseAction {
60 // ----------------------------------------------------- Instance Variables
61
62 /**
63 * Commons Logging instance.
64 */
65 protected static Log log = LogFactory.getLog(SwitchAction.class);
66
67 /**
68 * Process the specified HTTP request, and create the corresponding HTTP
69 * response (or forward to another web component that will create it).
70 * Return an <code>ActionForward</code> instance describing where and how
71 * control should be forwarded, or <code>null</code> if the response has
72 * already been completed.
73 *
74 * @param mapping The ActionMapping used to select this instance
75 * @param form The optional ActionForm bean for this request (if any)
76 * @param request The HTTP request we are processing
77 * @param response The HTTP response we are creating
78 * @return Return an <code>ActionForward</code> instance describing where
79 * and how control should be forwarded, or <code>null</code> if
80 * the response has already been completed.
81 * @throws Exception if an exception occurs
82 */
83 public ActionForward execute(ActionMapping mapping, ActionForm form,
84 HttpServletRequest request, HttpServletResponse response)
85 throws Exception {
86 // Identify the request parameters controlling our actions
87 String page = request.getParameter("page");
88 String prefix = request.getParameter("prefix");
89
90 if ((page == null) || (prefix == null)) {
91 String message = messages.getMessage("switch.required");
92
93 log.error(message);
94 throw new ServletException(message);
95 }
96
97 // Switch to the requested module
98 ModuleUtils.getInstance().selectModule(prefix, request,
99 getServlet().getServletContext());
100
101 if (request.getAttribute(Globals.MODULE_KEY) == null) {
102 String message = messages.getMessage("switch.prefix", prefix);
103
104 log.error(message);
105 throw new ServletException(message);
106 }
107
108 // Forward control to the specified module-relative URI
109 return (new ActionForward(page));
110 }
111 }