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Java > Open Source Codes > org > apache > struts > util > MessageResourcesFactory


1 /*
2  * $Id: MessageResourcesFactory.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.util;
21
22
23 import java.io.Serializable JavaDoc;
24 import org.apache.commons.logging.Log;
25 import org.apache.commons.logging.LogFactory;
26
27
28 /**
29  * Factory for <code>MessageResources</code> instances. The general usage
30  * pattern for this class is:
31  * <ul>
32  * <li>Call <code>MessageResourcesFactory().createFactory()</code> to retrieve
33  * a <code>MessageResourcesFactory</code> instance.</li>
34  * <li>Set properties as required to configure this factory instance to create
35  * <code>MessageResources</code> instances with desired
36  * characteristics.</li>
37  * <li>Call the <code>createResources()</code> method of the factory to
38  * retrieve a newly instantiated <code>MessageResources</code>
39  * instance.</li>
40  * </ul>
41  *
42  * @version $Rev: 54929 $ $Date: 2004-10-16 17:38:42 +0100 (Sat, 16 Oct 2004) $
43  */
44
45 public abstract class MessageResourcesFactory implements Serializable JavaDoc {
46
47
48     // ---------------------------------------------------- Instance Properties
49
50
51     /**
52      * The "return null" property value to which newly created
53      * MessageResourcess should be initialized.
54      */
55     protected boolean returnNull = true;
56
57     /**
58      * Get default value of the "returnNull" property used to initialize newly created
59      * MessageResourcess.
60      * @return default value of the "returnNull" property newly created
61      * MessageResourcess are initialized to.
62      */
63     public boolean getReturnNull() {
64         return (this.returnNull);
65     }
66
67     /**
68      * Set the default value of the "returnNull" property newly created
69      * MessageResourcess are initialized to.
70      * @param returnNull default value of the "returnNull" MessageResourcess are initialized to.
71      */
72     public void setReturnNull(boolean returnNull) {
73         this.returnNull = returnNull;
74     }
75
76
77     // --------------------------------------------------------- Public Methods
78
79
80     /**
81      * Create and return a newly instansiated <code>MessageResources</code>.
82      * This method must be implemented by concrete subclasses.
83      *
84      * @param config Configuration parameter(s) for the requested bundle
85      */
86     public abstract MessageResources createResources(String JavaDoc config);
87
88
89     // ------------------------------------------------------ Static Properties
90
91
92     /**
93      * The Java class to be used for
94      * <code>MessageResourcesFactory</code> instances.
95      */
96     protected static transient Class JavaDoc clazz = null;
97
98
99     /**
100      * Commons Logging instance.
101      */
102     private static Log LOG = LogFactory.getLog(MessageResourcesFactory.class);
103
104
105     /**
106      * The fully qualified class name to be used for
107      * <code>MessageResourcesFactory</code> instances.
108      */
109     protected static String JavaDoc factoryClass =
110         "org.apache.struts.util.PropertyMessageResourcesFactory";
111
112     /**
113      * The fully qualified class name that is used for
114      * <code>MessageResourcesFactory</code> instances.
115      * @return class name that is used for
116      * <code>MessageResourcesFactory</code> instances
117      */
118     public static String JavaDoc getFactoryClass() {
119         return (MessageResourcesFactory.factoryClass);
120     }
121
122     /**
123      * Set the fully qualified class name that is used for
124      * <code>MessageResourcesFactory</code> instances.
125      * @param factoryClass name that is used for
126      * <code>MessageResourcesFactory</code> instances
127      */
128     public static void setFactoryClass(String JavaDoc factoryClass) {
129         MessageResourcesFactory.factoryClass = factoryClass;
130         MessageResourcesFactory.clazz = null;
131     }
132
133
134     // --------------------------------------------------------- Static Methods
135
136
137     /**
138      * Create and return a <code>MessageResourcesFactory</code> instance of the
139      * appropriate class, which can be used to create customized
140      * <code>MessageResources</code> instances. If no such factory can be
141      * created, return <code>null</code> instead.
142      */
143     public static MessageResourcesFactory createFactory() {
144
145         // Construct a new instance of the specified factory class
146 try {
147             if (clazz == null)
148                 clazz = RequestUtils.applicationClass(factoryClass);
149             MessageResourcesFactory factory =
150                 (MessageResourcesFactory) clazz.newInstance();
151             return (factory);
152         } catch (Throwable JavaDoc t) {
153             LOG.error("MessageResourcesFactory.createFactory", t);
154             return (null);
155         }
156
157     }
158
159
160 }
161
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