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1   /*
2    * $Id: TilesAction.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  
22  package org.apache.struts.tiles.actions;
23  
24  import javax.servlet.ServletException;
25  import javax.servlet.http.HttpServletRequest;
26  import javax.servlet.http.HttpServletResponse;
27  
28  import org.apache.struts.action.Action;
29  import org.apache.struts.action.ActionForm;
30  import org.apache.struts.action.ActionForward;
31  import org.apache.struts.action.ActionMapping;
32  import org.apache.struts.tiles.ComponentContext;
33  
34  /**
35   * Base class for Tiles Actions.
36   * This class has the same role as Struts Action. It provides a method execute(...)
37   * called when action is invoked. The difference is, that the execute() method takes
38   * an additional parameter : tile context.
39   * This class extends Struts Action. Subclasses should override
40   * execute(ComponentContext ...) method instead of Struts
41   * execute(ActionMapping ...) method.
42   * @version $Rev: 471754 $ $Date: 2006-11-06 08:55:09 -0600 (Mon, 06 Nov 2006) $
43   */
44  public abstract class TilesAction extends Action {
45  
46      /**
47       * Original Struts Action's method.
48       * Retrieve current Tile context and call TilesAction execute method.
49       * Do not overload this method!
50       *
51       * @param mapping The ActionMapping used to select this instance.
52       * @param form The optional ActionForm bean for this request (if any).
53       * @param request The HTTP request we are processing.
54       * @param response The HTTP response we are creating.
55       *
56       * @exception Exception if the application business logic throws
57       *  an exception
58       * @since Struts 1.1
59       */
60      public ActionForward execute(
61          ActionMapping mapping,
62          ActionForm form,
63          HttpServletRequest request,
64          HttpServletResponse response)
65          throws Exception {
66  
67          // Try to retrieve tile context
68          ComponentContext context = ComponentContext.getContext(request);
69          if (context == null) {
70              throw new ServletException(
71                  "Can't find Tile context for '"
72                      + this.getClass().getName()
73                      + "'. TilesAction subclasses must be called from a Tile");
74          }
75  
76          return this.execute(context, mapping, form, request, response);
77      }
78  
79      /**
80       * Process the specified HTTP request and create the corresponding HTTP
81       * response (or forward to another web component that will create it),
82       * with provision for handling exceptions thrown by the business logic.
83       * <br>
84       * Override this method to provide functionality.
85       *
86       * @param context The current Tile context, containing Tile attributes.
87       * @param mapping The ActionMapping used to select this instance.
88       * @param form The optional ActionForm bean for this request (if any).
89       * @param request The HTTP request we are processing.
90       * @param response The HTTP response we are creating.
91       *
92       * @exception Exception if the application business logic throws
93       *  an exception
94       * @since Struts 1.1
95       */
96      public ActionForward execute(
97          ComponentContext context,
98          ActionMapping mapping,
99          ActionForm form,
100         HttpServletRequest request,
101         HttpServletResponse response)
102         throws Exception {
103 
104         return null;
105     }
106 
107 }