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Java > Open Source Codes > org > apache > struts > actions > ForwardAction


1 /*
2  * $Id: ForwardAction.java 54929 2004-10-16 16:38:42Z germuska $
3  *
4  * Copyright 2001-2004 The Apache Software Foundation.
5  *
6  * Licensed under the Apache License, Version 2.0 (the "License");
7  * you may not use this file except in compliance with the License.
8  * You may obtain a copy of the License at
9  *
10  * http://www.apache.org/licenses/LICENSE-2.0
11  *
12  * Unless required by applicable law or agreed to in writing, software
13  * distributed under the License is distributed on an "AS IS" BASIS,
14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15  * See the License for the specific language governing permissions and
16  * limitations under the License.
17  */
18
19 package org.apache.struts.actions;
20
21 import javax.servlet.ServletException JavaDoc;
22 import javax.servlet.http.HttpServletRequest JavaDoc;
23 import javax.servlet.http.HttpServletResponse JavaDoc;
24
25 import org.apache.struts.action.Action;
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.MessageResources;
30
31 /**
32  * <p>An <strong>Action</strong> that forwards to the context-relative
33  * URI specified by the <code>parameter</code> property of our associated
34  * <code>ActionMapping</code>. This can be used to integrate Struts with
35  * other business logic components that are implemented as servlets (or JSP
36  * pages), but still take advantage of the Struts controller servlet's
37  * functionality (such as processing of form beans).</p>
38  *
39  * <p>To configure the use of this Action in your
40  * <code>struts-config.xml</code> file, create an entry like this:</p>
41  *
42  * <code>
43  * &lt;action path="/saveSubscription"
44  * type="org.apache.struts.actions.ForwardAction"
45  * name="subscriptionForm"
46  * scope="request"
47  * input="/subscription.jsp"
48  * parameter="/path/to/processing/servlet"/&gt;
49  * </code>
50  *
51  * <p>which will forward control to the context-relative URI specified by the
52  * <code>parameter</code> attribute.</p>
53  *
54  * @version $Rev: 54929 $ $Date: 2004-10-16 17:38:42 +0100 (Sat, 16 Oct 2004) $
55  */
56 public class ForwardAction extends Action {
57
58
59     // ----------------------------------------------------- Instance Variables
60
61
62     /**
63      * The message resources for this package.
64      */
65     protected static MessageResources messages =
66      MessageResources.getMessageResources
67         ("org.apache.struts.actions.LocalStrings");
68
69
70     // --------------------------------------------------------- Public Methods
71
72
73     /**
74      * Process the specified HTTP request, and create the corresponding HTTP
75      * response (or forward to another web component that will create it).
76      * Return an <code>ActionForward</code> instance describing where and how
77      * control should be forwarded, or <code>null</code> if the response has
78      * already been completed.
79      *
80      * @param mapping The ActionMapping used to select this instance
81      * @param form The optional ActionForm bean for this request (if any)
82      * @param request The HTTP request we are processing
83      * @param response The HTTP response we are creating
84      *
85      * @exception Exception if an error occurs
86      */
87     public ActionForward execute(
88         ActionMapping mapping,
89         ActionForm form,
90         HttpServletRequest JavaDoc request,
91         HttpServletResponse JavaDoc response)
92         throws Exception JavaDoc {
93
94         // Create a RequestDispatcher the corresponding resource
95 String JavaDoc path = mapping.getParameter();
96
97         if (path == null) {
98             throw new ServletException JavaDoc(messages.getMessage("forward.path"));
99         }
100
101         // Let the controller handle the request
102 ActionForward retVal = new ActionForward(path);
103         retVal.setContextRelative(true);
104
105         return retVal;
106     }
107
108
109 }
110
111
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