1 /*
2 * $Id: FactorySet.java 471754 2006-11-06 14:55:09Z husted $
3 *
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21
22 package org.apache.struts.tiles.xmlDefinition;
23
24 import java.util.HashMap;
25 import java.util.Iterator;
26 import java.util.Map;
27
28 import javax.servlet.ServletContext;
29 import javax.servlet.ServletRequest;
30
31 import org.apache.struts.tiles.ComponentDefinition;
32 import org.apache.struts.tiles.ComponentDefinitionsFactory;
33 import org.apache.struts.tiles.DefinitionsFactoryException;
34 import org.apache.struts.tiles.FactoryNotFoundException;
35 import org.apache.struts.tiles.NoSuchDefinitionException;
36
37 /**
38 * Component Definitions factory.
39 * This factory contains several factories identified by a key. The
40 * getDefinition() method first looks for the factory key, retrieves or creates this
41 * factory and then calls its getDefinition().
42 */
43 public abstract class FactorySet implements ComponentDefinitionsFactory
44 {
45
46 /** Loaded factories */
47 protected Map factories=null;
48
49 /**
50 * Extract key that will be used to get the sub factory.
51 * @param name Name of requested definition.
52 * @param request Current servlet request.
53 * @param servletContext Current servlet context.
54 * @return Object.
55 */
56 abstract protected Object getDefinitionsFactoryKey(String name, ServletRequest request, ServletContext servletContext);
57
58 /**
59 * Get default factory.
60 * @return Default factory.
61 */
62 abstract protected DefinitionsFactory getDefaultFactory();
63
64 /**
65 * Get a factory by its key.
66 * If key is <code>null</code>, return defaultFactory.
67 * Search in loaded factories. If not found, create factory and store return value in
68 * loaded factories.
69 * @param key Key of requested definition.
70 * @param request Current servlet request.
71 * @param servletContext Current servlet context.
72 * @throws DefinitionsFactoryException If an error occur while creating factory.
73 */
74 protected DefinitionsFactory getFactory(Object key, ServletRequest request, ServletContext servletContext)
75 throws DefinitionsFactoryException
76 {
77 if(key == null )
78 return getDefaultFactory();
79
80 Object factory = factories.get( key );
81 if( factory == null )
82 {
83 // synchronize creation to avoid double creation by separate threads.
84 // Also, check if factory hasn't been created while waiting for synchronized
85 // section.
86 synchronized(factories)
87 {
88 factory = factories.get( key );
89 if( factory == null )
90 {
91 factory = createFactory( key, request, servletContext);
92 factories.put( key, factory );
93 } // end if
94 } // end synchronized
95 } // end if
96 return (DefinitionsFactory)factory;
97 }
98
99 /**
100 * Get a definition by its name.
101 *
102 * @param name Name of requested definition.
103 * @param request Current servlet request.
104 * @param servletContext Current servlet context.
105 * @throws NoSuchDefinitionException No definition found for specified name
106 * @throws DefinitionsFactoryException General exception
107 */
108 public ComponentDefinition getDefinition(String name, ServletRequest request, ServletContext servletContext)
109 throws NoSuchDefinitionException, DefinitionsFactoryException
110 {
111 if( factories == null )
112 throw new FactoryNotFoundException( "No definitions factory defined" );
113
114 Object key = getDefinitionsFactoryKey( name, request, servletContext);
115 DefinitionsFactory factory = getFactory( key, request, servletContext);
116 return factory.getDefinition( name, request, servletContext );
117 }
118
119 /**
120 * Create a factory for specified key.
121 * This method is called by getFactory() when the requested factory doesn't already exist.
122 * Must return a factory, or a default one.
123 * Real implementation needs to provide this method.
124 * @param key Key of requested definition.
125 * @param request Current servlet request.
126 * @param servletContext Current servlet context
127 * @throws DefinitionsFactoryException If an error occur while creating factory.
128 */
129 abstract protected DefinitionsFactory createFactory(Object key, ServletRequest request, ServletContext servletContext)
130 throws DefinitionsFactoryException;
131
132 /**
133 * Init factory set.
134 * @param servletContext Current servlet context
135 * @param properties properties used to initialized factory set;
136 */
137 abstract public void initFactory(ServletContext servletContext, Map properties)
138 throws DefinitionsFactoryException;
139
140 /**
141 * Constructor.
142 */
143 public FactorySet()
144 {
145 factories = new HashMap();
146 }
147
148 /**
149 * Return String representation.
150 * @return String representation.
151 */
152 public String toString()
153 {
154 Iterator i = factories.values().iterator();
155 StringBuffer buff = new StringBuffer( "all FactorySet's factory : \n" );
156 while( i.hasNext() )
157 {
158 buff.append( i.next().toString() ).append("\n");
159 }
160 return buff.toString();
161 }
162
163 }