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1   package org.apache.turbine.modules.layouts;
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.logging.Log;
20  import org.apache.commons.logging.LogFactory;
21  
22  import org.apache.ecs.ConcreteElement;
23  
24  import org.apache.turbine.TurbineConstants;
25  import org.apache.turbine.modules.Layout;
26  import org.apache.turbine.modules.ScreenLoader;
27  import org.apache.turbine.services.velocity.TurbineVelocity;
28  import org.apache.turbine.util.RunData;
29  import org.apache.turbine.util.template.TemplateNavigation;
30  
31  import org.apache.velocity.context.Context;
32  
33  /***
34   * This Layout module allows Velocity templates to be used as layouts.
35   * Since dynamic content is supposed to be primarily located in
36   * screens and navigations there should be relatively few reasons to
37   * subclass this Layout.
38   *
39   * This class uses ECS to render the layout.
40   *
41   * @author <a href="mailto:john.mcnally@clearink.com">John D. McNally</a>
42   * @author <a href="mailto:mbryson@mont.mindspring.com">Dave Bryson</a>
43   * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
44   * @version $Id: VelocityECSLayout.java 264148 2005-08-29 14:21:04Z henning $
45   * @deprecated you should use VelocityOnlyLayout
46   */
47  public class VelocityECSLayout
48      extends Layout
49  {
50      /*** Logging */
51      private static Log log = LogFactory.getLog(VelocityECSLayout.class);
52  
53      /*** The prefix for lookup up layout pages */
54      private String prefix = TurbineConstants.LAYOUT_PREFIX + "/";
55  
56      /*** Warn only once */
57      private static boolean hasWarned = false;
58  
59      /***
60       * C'tor warns once about deprecation.
61       */
62      public VelocityECSLayout()
63      {
64          if (!hasWarned)
65          {
66              log.warn("The VelocityECSLayout is deprecated. "
67                       + "Please switch to VelocityOnlyLayout.");
68              hasWarned = true;
69          }
70      }
71  
72      /***
73       * Build the layout.  Also sets the ContentType and Locale headers
74       * of the HttpServletResponse object.
75       *
76       * @param data Turbine information.
77       * @exception Exception a generic exception.
78       */
79      public void doBuild(RunData data)
80          throws Exception
81      {
82          // Get the context needed by Velocity.
83          Context context = TurbineVelocity.getContext(data);
84  
85          String screenName = data.getScreen();
86  
87          log.debug("Loading Screen " + screenName);
88  
89          // First, generate the screen and put it in the context so
90          // we can grab it the layout template.
91          ConcreteElement results =
92              ScreenLoader.getInstance().eval(data, screenName);
93  
94          String returnValue = (results == null) ? "" : results.toString();
95  
96          // variable for the screen in the layout template
97          context.put(TurbineConstants.SCREEN_PLACEHOLDER, returnValue);
98  
99          // variable to reference the navigation screen in the layout template
100         context.put(TurbineConstants.NAVIGATION_PLACEHOLDER,
101                     new TemplateNavigation(data));
102 
103         // Grab the layout template set in the VelocityPage.
104         // If null, then use the default layout template
105         // (done by the TemplateInfo object)
106         String templateName = data.getTemplateInfo().getLayoutTemplate();
107 
108         log.debug("Now trying to render layout " + templateName);
109 
110         // Finally, generate the layout template and add it to the body of the
111         // Document in the RunData.
112         data.getPage().getBody().addElement(TurbineVelocity
113                 .handleRequest(context, prefix +  templateName));
114     }
115 }