MessagesMap


1   /*
2    * Copyright 2002,2004 The Apache Software Foundation.
3    * 
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    * 
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    * 
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  
17  package org.apache.struts.faces.util;
18  
19  
20  import java.util.Collection  ;
21  import java.util.Locale  ;
22  import java.util.Map  ;
23  import java.util.Set  ;
24  
25  import org.apache.struts.util.MessageResources;
26  
27  
28  /**
29   * <p>A limited immutable <code>Map</code> implementation that wraps the
30   * <code>MessageResources</code> instance for the specified
31   * <code>Locale</code>.  Exposing the messages as a <code>Map</code>
32   * makes them easily accessible via value binding expressions, as
33   * well as JSP 2.0 expression language expressions.
34   */
35  
36  public class MessagesMap implements Map   {
37  
38  
39      // ------------------------------------------------------------ Constructors
40  
41  
42      /**
43       * <p>Construct a new {@link MessagesMap} instance that wraps the
44       * specified <code>MessageResources</code> instance, and returns messages
45       * for the specified <code>Locale</code>.</p>
46       *
47       * @param messages <code>MessageResources</code> instance to wrap
48       * @param locale <code>Locale</code> for which to retrieve messages,
49       *  or <code>null</code> for the system default <code>Locale</code>
50       *
51       * @exception NullPointerException if <code>messages</code>
52       *  is <code>null</code>
53       */
54      public MessagesMap(MessageResources messages, Locale   locale) {
55  
56          super();
57          if (messages == null) {
58              throw new NullPointerException  ();
59          }
60          this.messages = messages;
61          this.locale = locale;
62  
63      }
64  
65  
66      // ------------------------------------------------------ Instance Variables
67  
68  
69      /**
70       * <p>The <code>Locale</code> for which to return messages, or
71       * <code>null</code> for the system default <code>Locale</code>.</p>
72       */
73      private Locale   locale = null;
74  
75  
76      /**
77       * <p>The <code>MessageResources</code> being wrapped by this
78       * {@link MessagesMap}.</p>
79       */
80      private MessageResources messages = null;
81  
82  
83      // ---------------------------------------------------------- Public Methods
84  
85  
86      /**
87       * <p>The <code>clear()</code> method is not supported.</p>
88       */
89      public void clear() {
90  
91          throw new UnsupportedOperationException  ();
92  
93      }
94  
95  
96      /**
97       * <p>Return <code>true</code> if there is a message for the
98       * specified key.</p>
99       *
100      * @param key Message key to evaluate
101      */
102     public boolean containsKey(Object   key) {
103 
104         if (key == null) {
105             return (false);
106         } else {
107             return (messages.isPresent(locale, key.toString()));
108         }
109 
110     }
111 
112 
113     /**
114      * <p>The <code>containsValue()</code> method is not supported.</p>
115      *
116      * @param value Value to evaluate
117      */
118     public boolean containsValue(Object   value) {
119 
120         throw new UnsupportedOperationException  ();
121 
122     }
123 
124 
125     /**
126      * <p>The <code>entrySet()</code> method is not supported.</p>
127      */
128     public Set   entrySet() {
129 
130         throw new UnsupportedOperationException  ();
131 
132     }
133 
134 
135     /**
136      * <p>The <code>equals</code> method checks whether equal
137      * <code>MessageResources</code> and <code>Locale</code> are
138      * being wrapped.</p>
139      *
140      * @param o The object to be compared
141      */
142     public boolean equals(Object   o) {
143 
144         if (!(o instanceof MessagesMap)) {
145             return (false);
146         }
147         MessagesMap other = (MessagesMap) o;
148         if (!messages.equals(other.getMessages())) {
149             return (false);
150         }
151         if (locale == null) {
152             return (other.getLocale() == null);
153         } else {
154             return (locale.equals(other.getLocale()));
155         }
156 
157     }
158 
159 
160     /**
161      * <p>Return the message string for the specified key.</p>
162      *
163      * @param key Key for message to return
164      */
165     public Object   get(Object   key) {
166 
167         if (key == null) {
168             return ("??????");
169         } else {
170             return (messages.getMessage(locale, key.toString()));
171         }
172 
173     }
174 
175 
176     /**
177      * <p>The <code>hashCode()</code> method returns values that will
178      * be identical if the <code>equals</code> method returns <code>true</code>.
179      * </p>
180      */
181     public int hashCode() {
182 
183         int value = messages.hashCode();
184         if (locale != null) {
185             value = value ^ locale.hashCode();
186         }
187         return (value);
188 
189     }
190 
191 
192     /**
193      * <p>The <code>isEmpty()</code> method returns <code>false</code>, on the
194      * assumption that there is always at least one message available.</p>
195      */
196     public boolean isEmpty() {
197 
198         return (false);
199 
200     }
201 
202 
203     /**
204      * <p>The <code>keySet()</code> method is not supported.</p>
205      */
206     public Set   keySet() {
207 
208         throw new UnsupportedOperationException  ();
209 
210     }
211 
212 
213     /**
214      * <p>The <code>put()</code> method is not supported.</p>
215      *
216      * @param key Key to store
217      * @param value Value to store
218      */
219     public Object   put(Object   key, Object   value) {
220 
221         throw new UnsupportedOperationException  ();
222 
223     }
224 
225 
226     /**
227      * <p>The <code>putAll()</code> method is not supported.</p>
228      *
229      * @param map Keys and values to store
230      */
231     public void putAll(Map   map) {
232 
233         throw new UnsupportedOperationException  ();
234 
235     }
236 
237 
238     /**
239      * <p>The <code>remove()</code> method is not supported.</p>
240      *
241      * @param key Key to remove
242      */
243     public Object   remove(Object   key) {
244 
245         throw new UnsupportedOperationException  ();
246 
247     }
248 
249 
250     /**
251      * <p>The <code>size()</code> method is not supported.</p>
252      */
253     public int size() {
254 
255         throw new UnsupportedOperationException  ();
256 
257     }
258 
259 
260     /**
261      * <p>The <code>values()</code> method is not supported.</p>
262      */
263     public Collection   values() {
264 
265         throw new UnsupportedOperationException  ();
266 
267     }
268 
269 
270     // --------------------------------------------------------- Package Methods
271 
272 
273     /**
274      * <p>Return the <code>Locale</code> we object we are wrapping.</p>
275      */
276     Locale   getLocale() {
277 
278         return (this.locale);
279 
280     }
281 
282 
283     /**
284      * <p>Return the <code>MessageResources</code> object we are wrapping.</p>
285      */
286     MessageResources getMessages() {
287 
288         return (this.messages);
289 
290     }
291 
292 
293 
294 }
295
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