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Java > Open Source Codes > org > apache > turbine > util > template > TemplateNavigation


1 package org.apache.turbine.util.template;
2
3 /*
4  * Copyright 2001-2004 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,v 1.9.2.2 2004/05/20 03:27:24 seade Exp $
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 JavaDoc 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 JavaDoc 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 JavaDoc toString()
85     {
86         String JavaDoc module = null;
87         String JavaDoc returnValue = null;
88
89         try
90         {
91             if (template == null)
92             {
93                 returnValue = "Navigation Template is null (Might be unset)";
94                 throw new Exception JavaDoc(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 JavaDoc(returnValue);
104             }
105             
106             ConcreteElement results =
107                     NavigationLoader.getInstance().eval(data, module);
108             returnValue = results.toString();
109         }
110         catch (Exception JavaDoc 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 }
123
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