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Java > Open Source Codes > org > apache > struts > tiles > xmlDefinition > FactorySet


1 /*
2  * $Id: FactorySet.java 54929 2004-10-16 16:38:42Z germuska $
3  *
4  * Copyright 1999-2004 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
20 package org.apache.struts.tiles.xmlDefinition;
21
22 import java.util.HashMap JavaDoc;
23 import java.util.Iterator JavaDoc;
24 import java.util.Map JavaDoc;
25
26 import javax.servlet.ServletContext JavaDoc;
27 import javax.servlet.ServletRequest JavaDoc;
28
29 import org.apache.struts.tiles.ComponentDefinition;
30 import org.apache.struts.tiles.ComponentDefinitionsFactory;
31 import org.apache.struts.tiles.DefinitionsFactoryException;
32 import org.apache.struts.tiles.FactoryNotFoundException;
33 import org.apache.struts.tiles.NoSuchDefinitionException;
34
35 /**
36  * Component Definitions factory.
37  * This factory contains several factories identified by a key. The
38  * getDefinition() method first looks for the factory key, retrieves or creates this
39  * factory and then calls its getDefinition().
40  */
41 public abstract class FactorySet implements ComponentDefinitionsFactory
42 {
43
44     /** Loaded factories */
45   protected Map JavaDoc factories=null;
46
47   /**
48    * Extract key that will be used to get the sub factory.
49    * @param name Name of requested definition.
50    * @param request Current servlet request.
51    * @param servletContext Current servlet context.
52    * @return Object.
53    */
54   abstract protected Object JavaDoc getDefinitionsFactoryKey(String JavaDoc name, ServletRequest JavaDoc request, ServletContext JavaDoc servletContext);
55
56   /**
57    * Get default factory.
58    * @return Default factory.
59    */
60   abstract protected DefinitionsFactory getDefaultFactory();
61
62   /**
63    * Get a factory by its key.
64    * If key is <code>null</code>, return defaultFactory.
65    * Search in loaded factories. If not found, create factory and store return value in
66    * loaded factories.
67    * @param key Key of requested definition.
68    * @param request Current servlet request.
69    * @param servletContext Current servlet context.
70    * @throws DefinitionsFactoryException If an error occur while creating factory.
71    */
72   protected DefinitionsFactory getFactory(Object JavaDoc key, ServletRequest JavaDoc request, ServletContext JavaDoc servletContext)
73     throws DefinitionsFactoryException
74   {
75   if(key == null )
76     return getDefaultFactory();
77
78   Object JavaDoc factory = factories.get( key );
79   if( factory == null )
80     {
81       // synchronize creation to avoid double creation by separate threads.
82 // Also, check if factory hasn't been created while waiting for synchronized
83 // section.
84 synchronized(factories)
85       {
86       factory = factories.get( key );
87       if( factory == null )
88         {
89         factory = createFactory( key, request, servletContext);
90         factories.put( key, factory );
91         } // end if
92 } // end synchronized
93 } // end if
94 return (DefinitionsFactory)factory;
95   }
96
97   /**
98    * Get a definition by its name.
99    *
100    * @param name Name of requested definition.
101    * @param request Current servlet request.
102    * @param servletContext Current servlet context.
103    * @throws NoSuchDefinitionException No definition found for specified name
104    * @throws DefinitionsFactoryException General exception
105    */
106   public ComponentDefinition getDefinition(String JavaDoc name, ServletRequest JavaDoc request, ServletContext JavaDoc servletContext)
107     throws NoSuchDefinitionException, DefinitionsFactoryException
108   {
109   if( factories == null )
110     throw new FactoryNotFoundException( "No definitions factory defined" );
111
112   Object JavaDoc key = getDefinitionsFactoryKey( name, request, servletContext);
113   DefinitionsFactory factory = getFactory( key, request, servletContext);
114   return factory.getDefinition( name, request, servletContext );
115   }
116
117   /**
118    * Create a factory for specified key.
119    * This method is called by getFactory() when the requested factory doesn't already exist.
120    * Must return a factory, or a default one.
121    * Real implementation needs to provide this method.
122    * @param key Key of requested definition.
123    * @param request Current servlet request.
124    * @param servletContext Current servlet context
125    * @throws DefinitionsFactoryException If an error occur while creating factory.
126    */
127   abstract protected DefinitionsFactory createFactory(Object JavaDoc key, ServletRequest JavaDoc request, ServletContext JavaDoc servletContext)
128           throws DefinitionsFactoryException;
129
130   /**
131    * Init factory set.
132    * @param servletContext Current servlet context
133    * @param properties properties used to initialized factory set;
134    */
135   abstract public void initFactory(ServletContext JavaDoc servletContext, Map JavaDoc properties)
136     throws DefinitionsFactoryException;
137
138   /**
139    * Constructor.
140    */
141   public FactorySet()
142   {
143   factories = new HashMap JavaDoc();
144   }
145
146     /**
147      * Return String representation.
148      * @return String representation.
149      */
150   public String JavaDoc toString()
151     {
152     Iterator JavaDoc i = factories.values().iterator();
153     StringBuffer JavaDoc buff = new StringBuffer JavaDoc( "all FactorySet's factory : \n" );
154     while( i.hasNext() )
155       {
156       buff.append( i.next().toString() ).append("\n");
157       }
158     return buff.toString();
159     }
160
161 }
162
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