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    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.
   28    *
   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
   34    * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   35    * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   36    * DISCLAIMED.  IN NO EVENT SHALL THE VISIGOTH SOFTWARE SOCIETY OR
   37    * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   38    * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   39    * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
   40    * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   41    * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   42    * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   43    * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   44    * SUCH DAMAGE.
   45    * ====================================================================
   46    *
   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;
   56   import java.util.Map;
   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    * Base class for hash models keyed by Java class names. 
   65    * @author Attila Szegedi
   66    * @version $Id: ClassBasedModelFactory.java,v 1.1.2.2 2006/11/12 10:23:02 szegedia Exp $
   67    */
   68   abstract class ClassBasedModelFactory implements TemplateHashModel {
   69       private final BeansWrapper wrapper;
   70       private final Map cache = new HashMap();
   71       
   72       protected ClassBasedModelFactory(BeansWrapper wrapper) {
   73           this.wrapper = wrapper;
   74       }
   75   
   76       public TemplateModel get(String key) throws TemplateModelException {
   77           synchronized(cache) {
   78               TemplateModel model = (TemplateModel)cache.get(key);
   79               if(model == null) {
   80                   try {
   81                       Class clazz = ClassUtil.forName(key);
   82                       model = createModel(clazz);
   83                       // This is called so that we trigger the
   84                       // class-reloading detector. If there was a class reload,
   85                       // the wrapper will in turn call our clearCache method.
   86                       wrapper.introspectClass(clazz);
   87                   } catch(Exception e) {
   88                       throw new TemplateModelException(e);
   89                   }
   90                   cache.put(key, model);
   91               }
   92               return model;
   93           }
   94       }
   95       
   96       void clearCache() {
   97           synchronized(cache) {
   98               cache.clear();
   99           }
  100       }
  101   
  102       public boolean isEmpty() {
  103           return false;
  104       }
  105       
  106       protected abstract TemplateModel createModel(Class clazz) 
  107       throws TemplateModelException;
  108       
  109       protected BeansWrapper getWrapper() {
  110           return wrapper;
  111       }
  112   }

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