1 /*
2 * $Id: MessageResourcesFactory.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 package org.apache.struts.util;
22
23 import org.apache.commons.logging.Log;
24 import org.apache.commons.logging.LogFactory;
25 import org.apache.struts.config.MessageResourcesConfig;
26
27 import java.io.Serializable;
28
29 /**
30 * Factory for <code>MessageResources</code> instances. The general usage
31 * pattern for this class is:
32 *
33 * <ul>
34 *
35 * <li>Call <code>MessageResourcesFactory().createFactory()</code> to retrieve
36 * a <code>MessageResourcesFactory</code> instance.</li> <li>Set properties as
37 * required to configure this factory instance to create
38 * <code>MessageResources</code> instances with desired characteristics.</li>
39 *
40 * <li>Call the <code>createResources()</code> method of the factory to
41 * retrieve a newly instantiated <code>MessageResources</code> instance.</li>
42 *
43 * </ul>
44 *
45 * @version $Rev: 471754 $ $Date: 2005-08-29 23:57:50 -0400 (Mon, 29 Aug 2005)
46 * $
47 */
48 public abstract class MessageResourcesFactory implements Serializable {
49 // ------------------------------------------------------ Static Properties
50
51 /**
52 * The Java class to be used for <code>MessageResourcesFactory</code>
53 * instances.
54 */
55 protected static transient Class clazz = null;
56
57 /**
58 * Commons Logging instance.
59 */
60 private static Log LOG = LogFactory.getLog(MessageResourcesFactory.class);
61
62 /**
63 * The fully qualified class name to be used for <code>MessageResourcesFactory</code>
64 * instances.
65 */
66 protected static String factoryClass =
67 "org.apache.struts.util.PropertyMessageResourcesFactory";
68
69 // ---------------------------------------------------- Instance Properties
70
71 /**
72 * Configuration information for Message Resources.
73 */
74 protected MessageResourcesConfig config;
75
76 /**
77 * The "return null" property value to which newly created
78 * MessageResourcess should be initialized.
79 */
80 protected boolean returnNull = true;
81
82 /**
83 * Set the configuration information for Message Resources.
84 *
85 * @since Struts 1.2.8
86 */
87 public MessageResourcesConfig getConfig() {
88 return config;
89 }
90
91 /**
92 * Return the configuration information for Message Resources.
93 *
94 * @since Struts 1.2.8
95 */
96 public void setConfig(MessageResourcesConfig config) {
97 this.config = config;
98 }
99
100 /**
101 * Get default value of the "returnNull" property used to initialize newly
102 * created MessageResourcess.
103 *
104 * @return default value of the "returnNull" property newly created
105 * MessageResourcess are initialized to.
106 */
107 public boolean getReturnNull() {
108 return (this.returnNull);
109 }
110
111 /**
112 * Set the default value of the "returnNull" property newly created
113 * MessageResourcess are initialized to.
114 *
115 * @param returnNull default value of the "returnNull" MessageResourcess
116 * are initialized to.
117 */
118 public void setReturnNull(boolean returnNull) {
119 this.returnNull = returnNull;
120 }
121
122 // --------------------------------------------------------- Public Methods
123
124 /**
125 * Create and return a newly instansiated <code>MessageResources</code>.
126 * This method must be implemented by concrete subclasses.
127 *
128 * @param config Configuration parameter(s) for the requested bundle
129 */
130 public abstract MessageResources createResources(String config);
131
132 /**
133 * The fully qualified class name that is used for <code>MessageResourcesFactory</code>
134 * instances.
135 *
136 * @return class name that is used for <code>MessageResourcesFactory</code>
137 * instances
138 */
139 public static String getFactoryClass() {
140 return (MessageResourcesFactory.factoryClass);
141 }
142
143 /**
144 * Set the fully qualified class name that is used for
145 * <code>MessageResourcesFactory</code> instances.
146 *
147 * @param factoryClass name that is used for <code>MessageResourcesFactory</code>
148 * instances
149 */
150 public static void setFactoryClass(String factoryClass) {
151 MessageResourcesFactory.factoryClass = factoryClass;
152 MessageResourcesFactory.clazz = null;
153 }
154
155 // --------------------------------------------------------- Static Methods
156
157 /**
158 * Create and return a <code>MessageResourcesFactory</code> instance of
159 * the appropriate class, which can be used to create customized
160 * <code>MessageResources</code> instances. If no such factory can be
161 * created, return <code>null</code> instead.
162 */
163 public static MessageResourcesFactory createFactory() {
164 // Construct a new instance of the specified factory class
165 try {
166 if (clazz == null) {
167 clazz = RequestUtils.applicationClass(factoryClass);
168 }
169
170 MessageResourcesFactory factory =
171 (MessageResourcesFactory) clazz.newInstance();
172
173 return (factory);
174 } catch (Throwable t) {
175 LOG.error("MessageResourcesFactory.createFactory", t);
176
177 return (null);
178 }
179 }
180 }