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1   /*
2    * $Id: ForwardAction.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.struts.action.ActionForm;
24  import org.apache.struts.action.ActionForward;
25  import org.apache.struts.action.ActionMapping;
26  
27  import javax.servlet.ServletException;
28  import javax.servlet.http.HttpServletRequest;
29  import javax.servlet.http.HttpServletResponse;
30  
31  /**
32   * <p>An <strong>Action</strong> that forwards to the context-relative URI
33   * 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 <code>struts-config.xml</code>
40   * file, create an entry like this:</p>
41   *
42   * <code> &lt;action path="/saveSubscription" type="org.apache.struts.actions.ForwardAction"
43   * name="subscriptionForm" scope="request" input="/subscription.jsp"
44   * parameter="/path/to/processing/servlet"/&gt; </code>
45   *
46   * <p>which will forward control to the context-relative URI specified by the
47   * <code>parameter</code> attribute.</p>
48   *
49   * @version $Rev: 471754 $ $Date: 2005-08-14 17:24:39 -0400 (Sun, 14 Aug 2005)
50   *          $
51   */
52  public class ForwardAction extends BaseAction {
53      // ----------------------------------------------------- Instance Variables
54  
55      /**
56       * Process the specified HTTP request, and create the corresponding HTTP
57       * response (or forward to another web component that will create it).
58       * Return an <code>ActionForward</code> instance describing where and how
59       * control should be forwarded, or <code>null</code> if the response has
60       * already been completed.
61       *
62       * @param mapping  The ActionMapping used to select this instance
63       * @param form     The optional ActionForm bean for this request (if any)
64       * @param request  The HTTP request we are processing
65       * @param response The HTTP response we are creating
66       * @return The forward to which control should be transferred, or
67       *         <code>null</code> if the response has been completed.
68       * @throws Exception if an error occurs
69       */
70      public ActionForward execute(ActionMapping mapping, ActionForm form,
71          HttpServletRequest request, HttpServletResponse response)
72          throws Exception {
73          // Create a RequestDispatcher the corresponding resource
74          String path = mapping.getParameter();
75  
76          if (path == null) {
77              throw new ServletException(messages.getMessage("forward.path"));
78          }
79  
80          // Let the controller handle the request
81          ActionForward retVal = new ActionForward(path);
82  
83          return retVal;
84      }
85  }