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Java > Open Source Codes > freemarker > ext > beans > StaticModels


1 /*
2  * Copyright (c) 2003 The Visigoth Software Society. All rights
3  * reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  *
9  * 1. Redistributions of source code must retain the above copyright
10  * notice, this list of conditions and the following disclaimer.
11  *
12  * 2. Redistributions in binary form must reproduce the above copyright
13  * notice, this list of conditions and the following disclaimer in
14  * the documentation and/or other materials provided with the
15  * distribution.
16  *
17  * 3. The end-user documentation included with the redistribution, if
18  * any, must include the following acknowledgement:
19  * "This product includes software developed by the
20  * Visigoth Software Society (http://www.visigoths.org/)."
21  * Alternately, this acknowledgement may appear in the software itself,
22  * if and wherever such third-party acknowledgements normally appear.
23  *
24  * 4. Neither the name "FreeMarker", "Visigoth", nor any of the names of the
25  * project contributors may be used to endorse or promote products derived
26  * from this software without prior written permission. For written
27  * permission, please contact visigoths@visigoths.org.
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29  * 5. Products derived from this software may not be called "FreeMarker" or "Visigoth"
30  * nor may "FreeMarker" or "Visigoth" appear in their names
31  * without prior written permission of the Visigoth Software Society.
32  *
33  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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35  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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47  * This software consists of voluntary contributions made by many
48  * individuals on behalf of the Visigoth Software Society. For more
49  * information on the Visigoth Software Society, please see
50  * http://www.visigoths.org/
51  */
52
53 package freemarker.ext.beans;
54
55 import java.util.HashMap JavaDoc;
56 import java.util.Map JavaDoc;
57
58 import freemarker.template.TemplateHashModel;
59 import freemarker.template.TemplateModel;
60 import freemarker.template.TemplateModelException;
61 import freemarker.template.utility.ClassUtil;
62
63 /**
64  * Utility class for instantiating {@link StaticModel} instances from
65  * templates. If your template's data model contains an instance of
66  * StaticModels (named, say <tt>StaticModels</tt>), then you can
67  * instantiate an arbitrary StaticModel using get syntax (i.e.
68  * <tt>StaticModels["java.lang.System"].currentTimeMillis()</tt>).
69  * @author Attila Szegedi
70  * @version $Id: StaticModels.java,v 1.12 2003/03/06 13:16:30 szegedia Exp $
71  */
72 final class StaticModels
73 implements
74     TemplateHashModel
75 {
76     private final BeansWrapper wrapper;
77     private final Map JavaDoc cache = new HashMap JavaDoc();
78     
79     StaticModels(BeansWrapper wrapper)
80     {
81         this.wrapper = wrapper;
82     }
83
84     /**
85      * Returns a {@link StaticModel} for the fully qualified class name
86      * passed as the key.
87      */
88     public TemplateModel get(String JavaDoc key)
89     throws
90         TemplateModelException
91     {
92         synchronized(cache)
93         {
94             TemplateModel model = (TemplateModel)cache.get(key);
95             if(model == null)
96             {
97                 try
98                 {
99                     Class JavaDoc clazz = ClassUtil.forName(key);
100                     model = new StaticModel(clazz, wrapper);
101                     // This is called so that we trigger the
102 // class-reloading detector. If there was a class reload,
103 // the wrapper will in turn call our clearCache method.
104 wrapper.introspectClass(clazz);
105                 }
106                 catch(Exception JavaDoc e)
107                 {
108                     throw new TemplateModelException(e);
109                 }
110                 cache.put(key, model);
111             }
112             return model;
113         }
114     }
115     
116     void clearCache()
117     {
118         synchronized(cache)
119         {
120             cache.clear();
121         }
122     }
123
124     public boolean isEmpty()
125     {
126         return false;
127     }
128 }
129
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