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1   package org.apache.turbine.util.template;
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.modules.NavigationLoader;
25  
26  import org.apache.turbine.services.template.TurbineTemplate;
27  
28  import org.apache.turbine.util.RunData;
29  
30  /***
31   * Returns output of a Navigation module.  An instance of this is
32   * placed in the WebMacro context by the WebMacroSiteLayout.  This
33   * allows template authors to set the navigation template they'd like
34   * to place in their templates.  Here's how it's used in a
35   * template:
36   *
37   * <p><code>
38   * $navigation.setTemplate("admin_navigation.wm")
39   * </code>
40   *
41   * @author <a href="mbryson@mont.mindspring.com">Dave Bryson</a>
42   * @version $Id: TemplateNavigation.java 264148 2005-08-29 14:21:04Z henning $
43   */
44  public class TemplateNavigation
45  {
46      /*** Logging */
47      private static Log log = LogFactory.getLog(TemplateNavigation.class);
48  
49      /* The RunData object. */
50      private RunData data;
51  
52      /* The name of the navigation template. */
53      private String template = null;
54  
55      /***
56       * Constructor
57       *
58       * @param data A Turbine RunData object.
59       */
60      public TemplateNavigation(RunData data)
61      {
62          this.data = data;
63      }
64  
65      /***
66       * Set the template.
67       *
68       * @param template A String with the name of the navigation
69       * template.
70       * @return A TemplateNavigation (self).
71       */
72      public TemplateNavigation setTemplate(String template)
73      {
74          log.debug("setTemplate(" + template + ")");
75          this.template = template;
76          return this;
77      }
78  
79      /***
80       * Builds the output of the navigation template.
81       *
82       * @return A String.
83       */
84      public String toString()
85      {
86          String module = null;
87          String returnValue = null;
88  
89          try
90          {
91              if (template == null)
92              {
93                  returnValue = "Navigation Template is null (Might be unset)";
94                  throw new Exception(returnValue);
95              }
96  
97              data.getTemplateInfo().setNavigationTemplate(template);
98              module = TurbineTemplate.getNavigationName(template);
99  
100             if (module == null)
101             {
102                 returnValue = "Template Service returned null for Navigation Template " + template;
103                 throw new Exception(returnValue);
104             }
105 
106             ConcreteElement results =
107                     NavigationLoader.getInstance().eval(data, module);
108             returnValue = results.toString();
109         }
110         catch (Exception e)
111         {
112             if (returnValue == null)
113             {
114                 returnValue = "Error processing navigation template: "
115                         + template + ", using module: " + module;
116             }
117             log.error(returnValue, e);
118         }
119 
120         return returnValue;
121     }
122 }