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1   package org.apache.turbine.modules.screens;
2   
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  import org.apache.commons.lang.StringUtils;
23  
24  import org.apache.ecs.ConcreteElement;
25  
26  import org.apache.turbine.TurbineConstants;
27  import org.apache.turbine.services.jsp.TurbineJsp;
28  import org.apache.turbine.services.template.TurbineTemplate;
29  import org.apache.turbine.util.RunData;
30  
31  /***
32   * Base JSP Screen that should be subclassed by screens that want to
33   * use JSP.  Subclasses should override the doBuildTemplate() method.
34   *
35   * @author <a href="mailto:john.mcnally@clearink.com">John D. McNally</a>
36   * @author Frank Y. Kim
37   * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
38   * @version $Id: BaseJspScreen.java 534527 2007-05-02 16:10:59Z tv $
39   */
40  public class BaseJspScreen
41          extends TemplateScreen
42  {
43      /*** The prefix for lookup up screen pages */
44      private String prefix = TurbineConstants.SCREEN_PREFIX + "/";
45  
46      /***
47       * Method that sets up beans and forward the request to the JSP.
48       *
49       * @param data Turbine information.
50       * @return null - the JSP sends the information.
51       * @exception Exception, a generic exception.
52       */
53      public ConcreteElement buildTemplate(RunData data)
54              throws Exception
55      {
56          String screenTemplate = data.getTemplateInfo().getScreenTemplate();
57          // get the name of the JSP we want to use
58          String templateName
59              = TurbineTemplate.getScreenTemplateName(screenTemplate);
60  
61          // The Template Service could not find the Screen
62          if (StringUtils.isEmpty(templateName))
63          {
64              log.error("Screen " + screenTemplate + " not found!");
65              throw new Exception("Could not find screen for " + screenTemplate);
66          }
67  
68          // let service know whether we are using a layout
69          TurbineJsp.handleRequest(data, prefix + templateName,
70                                   getLayout(data) == null);
71  
72          return null;
73      }
74  
75      /***
76       * Method to be overidden by subclasses to include data in beans, etc.
77       *
78       * @param data, the Rundata object
79       * @exception Exception, a generic exception.
80       */
81      protected void doBuildTemplate(RunData data)
82          throws Exception
83      {
84      }
85  }