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1   package org.apache.turbine.modules.screens;
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.commons.lang.StringUtils;
20  
21  import org.apache.ecs.ConcreteElement;
22  
23  import org.apache.turbine.TurbineConstants;
24  import org.apache.turbine.services.jsp.TurbineJsp;
25  import org.apache.turbine.services.template.TurbineTemplate;
26  import org.apache.turbine.util.RunData;
27  
28  /***
29   * Base JSP Screen that should be subclassed by screens that want to
30   * use JSP.  Subclasses should override the doBuildTemplate() method.
31   *
32   * @author <a href="mailto:john.mcnally@clearink.com">John D. McNally</a>
33   * @author Frank Y. Kim
34   * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
35   * @version $Id: BaseJspScreen.java 264148 2005-08-29 14:21:04Z henning $
36   */
37  public class BaseJspScreen
38          extends TemplateScreen
39  {
40      /*** The prefix for lookup up screen pages */
41      private String prefix = TurbineConstants.SCREEN_PREFIX + "/";
42  
43      /***
44       * Method that sets up beans and forward the request to the JSP.
45       *
46       * @param data Turbine information.
47       * @return null - the JSP sends the information.
48       * @exception Exception, a generic exception.
49       */
50      public ConcreteElement buildTemplate(RunData data)
51              throws Exception
52      {
53          String screenTemplate = data.getTemplateInfo().getScreenTemplate();
54          // get the name of the JSP we want to use
55          String templateName
56              = TurbineTemplate.getScreenTemplateName(screenTemplate);
57  
58          // The Template Service could not find the Screen
59          if (StringUtils.isEmpty(templateName))
60          {
61              log.error("Screen " + screenTemplate + " not found!");
62              throw new Exception("Could not find screen for " + screenTemplate);
63          }
64  
65          // let service know whether we are using a layout
66          TurbineJsp.handleRequest(data, prefix + templateName,
67                                   getLayout(data) == null);
68  
69          return null;
70      }
71  
72      /***
73       * Method to be overidden by subclasses to include data in beans, etc.
74       *
75       * @param data, the Rundata object
76       * @exception Exception, a generic exception.
77       */
78      protected void doBuildTemplate(RunData data)
79          throws Exception
80      {
81      }
82  }