View Javadoc

1   package org.apache.turbine.modules.actions;
2   
3   /*
4    * Copyright 2001-2005 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  import org.apache.turbine.modules.screens.TemplateScreen;
20  import org.apache.turbine.services.velocity.TurbineVelocity;
21  import org.apache.turbine.util.RunData;
22  import org.apache.turbine.util.velocity.VelocityActionEvent;
23  import org.apache.velocity.context.Context;
24  
25  /***
26   * This class provides a convenience methods for Velocity Actions
27   * to use. Since this class is abstract, it should only be extended
28   * and not used directly.
29   *
30   * @author <a href="mailto:jon@latchkey.com">Jon S. Stevens</a>
31   * @author <a href="mailto:jvanzyl@periapt.com">Jason van Zyl</a>
32   * @version $Id: VelocityAction.java 264148 2005-08-29 14:21:04Z henning $
33   */
34  public abstract class VelocityAction extends VelocityActionEvent
35  {
36      /***
37       * You SHOULD NOT override this method and implement it in your
38       * action.
39       *
40       * @param data Turbine information.
41       * @throws Exception a generic exception.
42       */
43      public void doPerform(RunData data)
44              throws Exception
45      {
46          doPerform(data, getContext(data));
47      }
48  
49      /***
50       * You SHOULD override this method and implement it in your
51       * action.
52       *
53       * @param data Turbine information.
54       * @param context Context for web pages.
55       * @throws Exception a generic exception.
56       */
57      public abstract void doPerform(RunData data,
58                                     Context context)
59              throws Exception;
60  
61      /***
62       * Sets up the context and then calls super.perform(); thus,
63       * subclasses don't have to worry about getting a context
64       * themselves!
65       *
66       * @param data Turbine information.
67       * @throws Exception a generic exception.
68       */
69      protected void perform(RunData data)
70              throws Exception
71      {
72          super.perform(data);
73      }
74  
75      /***
76       * This method is used when you want to short circuit an Action
77       * and change the template that will be executed next.
78       *
79       * @param data Turbine information.
80       * @param template The template that will be executed next.
81       */
82      public void setTemplate(RunData data,
83                              String template)
84      {
85          TemplateScreen.setTemplate(data, template);
86      }
87  
88      /***
89       * Return the Context needed by Velocity.
90       *
91       * @param data Turbine information.
92       * @return Context, a context for web pages.
93       */
94      protected Context getContext(RunData data)
95      {
96          return TurbineVelocity.getContext(data);
97      }
98  }