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1   /*
2    * $Id: ServletDispatcherResult.java 471756 2006-11-06 15:01:43Z 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.struts2.dispatcher;
22  
23  import javax.servlet.RequestDispatcher;
24  import javax.servlet.http.HttpServletRequest;
25  import javax.servlet.http.HttpServletResponse;
26  import javax.servlet.jsp.PageContext;
27  
28  import org.apache.commons.logging.Log;
29  import org.apache.commons.logging.LogFactory;
30  import org.apache.struts2.ServletActionContext;
31  
32  import com.opensymphony.xwork2.ActionInvocation;
33  
34  
35  /***
36   * <!-- START SNIPPET: description -->
37   *
38   * Includes or forwards to a view (usually a jsp). Behind the scenes Struts
39   * will use a RequestDispatcher, where the target servlet/JSP receives the same
40   * request/response objects as the original servlet/JSP. Therefore, you can pass
41   * data between them using request.setAttribute() - the Struts action is
42   * available.
43   * <p/>
44   * There are three possible ways the result can be executed:
45   *
46   * <ul>
47   *
48   * <li>If we are in the scope of a JSP (a PageContext is available), PageContext's
49   * {@link PageContext#include(String) include} method is called.</li>
50   *
51   * <li>If there is no PageContext and we're not in any sort of include (there is no
52   * "javax.servlet.include.servlet_path" in the request attributes), then a call to
53   * {@link RequestDispatcher#forward(javax.servlet.ServletRequest, javax.servlet.ServletResponse) forward}
54   * is made.</li>
55   *
56   * <li>Otherwise, {@link RequestDispatcher#include(javax.servlet.ServletRequest, javax.servlet.ServletResponse) include}
57   * is called.</li>
58   *
59   * </ul>
60   * <!-- END SNIPPET: description -->
61   *
62   * <b>This result type takes the following parameters:</b>
63   *
64   * <!-- START SNIPPET: params -->
65   *
66   * <ul>
67   *
68   * <li><b>location (default)</b> - the location to go to after execution (ex. jsp).</li>
69   *
70   * <li><b>parse</b> - true by default. If set to false, the location param will not be parsed for Ognl expressions.</li>
71   *
72   * </ul>
73   *
74   * <!-- END SNIPPET: params -->
75   *
76   * <b>Example:</b>
77   *
78   * <pre><!-- START SNIPPET: example -->
79   * &lt;result name="success" type="dispatcher"&gt;
80   *   &lt;param name="location"&gt;foo.jsp&lt;/param&gt;
81   * &lt;/result&gt;
82   * <!-- END SNIPPET: example --></pre>
83   *
84   * This result follows the same rules from {@link StrutsResultSupport}.
85   *
86   * @see javax.servlet.RequestDispatcher
87   */
88  public class ServletDispatcherResult extends StrutsResultSupport {
89  
90      private static final long serialVersionUID = -1970659272360685627L;
91  
92      private static final Log log = LogFactory.getLog(ServletDispatcherResult.class);
93  
94      public ServletDispatcherResult() {
95          super();
96      }
97  
98      public ServletDispatcherResult(String location) {
99          super(location);
100     }
101 
102     /***
103      * Dispatches to the given location. Does its forward via a RequestDispatcher. If the
104      * dispatch fails a 404 error will be sent back in the http response.
105      *
106      * @param finalLocation the location to dispatch to.
107      * @param invocation    the execution state of the action
108      * @throws Exception if an error occurs. If the dispatch fails the error will go back via the
109      *                   HTTP request.
110      */
111     public void doExecute(String finalLocation, ActionInvocation invocation) throws Exception {
112         if (log.isDebugEnabled()) {
113             log.debug("Forwarding to location " + finalLocation);
114         }
115 
116         PageContext pageContext = ServletActionContext.getPageContext();
117 
118         if (pageContext != null) {
119             pageContext.include(finalLocation);
120         } else {
121             HttpServletRequest request = ServletActionContext.getRequest();
122             HttpServletResponse response = ServletActionContext.getResponse();
123             RequestDispatcher dispatcher = request.getRequestDispatcher(finalLocation);
124 
125             // if the view doesn't exist, let's do a 404
126             if (dispatcher == null) {
127                 response.sendError(404, "result '" + finalLocation + "' not found");
128 
129                 return;
130             }
131 
132             // If we're included, then include the view
133             // Otherwise do forward
134             // This allow the page to, for example, set content type
135             if (!response.isCommitted() && (request.getAttribute("javax.servlet.include.servlet_path") == null)) {
136                 request.setAttribute("struts.view_uri", finalLocation);
137                 request.setAttribute("struts.request_uri", request.getRequestURI());
138 
139                 dispatcher.forward(request, response);
140             } else {
141                 dispatcher.include(request, response);
142             }
143         }
144     }
145 }