CmsMultiMessages


1   /*
2    * File   : $Source: /usr/local/cvs/opencms/src/org/opencms/i18n/CmsMultiMessages.java,v $
3    * Date   : $Date: 2006/03/27 14:53:01 $
4    * Version: $Revision: 1.16 $
5    *
6    * This library is part of OpenCms -
7    * the Open Source Content Mananagement System
8    *
9    * Copyright (c) 2005 Alkacon Software GmbH (http://www.alkacon.com)
10   *
11   * This library is free software; you can redistribute it and/or
12   * modify it under the terms of the GNU Lesser General Public
13   * License as published by the Free Software Foundation; either
14   * version 2.1 of the License, or (at your option) any later version.
15   *
16   * This library is distributed in the hope that it will be useful,
17   * but WITHOUT ANY WARRANTY; without even the implied warranty of
18   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19   * Lesser General Public License for more details.
20   *
21   * For further information about Alkacon Software GmbH, please see the
22   * company website: http://www.alkacon.com
23   *
24   * For further information about OpenCms, please see the
25   * project website: http://www.opencms.org
26   * 
27   * You should have received a copy of the GNU Lesser General Public
28   * License along with this library; if not, write to the Free Software
29   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
30   */
31  
32  package org.opencms.i18n;
33  
34  import org.opencms.main.CmsIllegalArgumentException;
35  import org.opencms.main.CmsLog;
36  
37  import java.util.ArrayList  ;
38  import java.util.Hashtable  ;
39  import java.util.Iterator  ;
40  import java.util.List  ;
41  import java.util.Locale  ;
42  import java.util.Map  ;
43  
44  import org.apache.commons.logging.Log;
45  
46  /**
47   * Provides access to the localized messages for several resource bundles simultaneously.<p>
48   * 
49   * Messages are cached for faster lookup. If a localized key is contained in more then one resource bundle,
50   * it will be used only from the resource bundle where it was first found in. The resource bundle order is undefined. It is therefore 
51   * recommended to ensure the uniqueness of all module keys by placing a special prefix in front of all keys of a resource bundle.<p>
52   * 
53   * @author Alexander Kandzior 
54   * @author Michael Moossen 
55   * 
56   * @version $Revision: 1.16 $ 
57   * 
58   * @since 6.0.0 
59   */
60  public class CmsMultiMessages extends CmsMessages {
61  
62      /** Constant for the multi bundle name. */
63      public static final String   MULTI_BUNDLE_NAME = CmsMultiMessages.class.getName();
64  
65      /** Null String value for caching of null message results. */
66      public static final String   NULL_STRING = "null";
67  
68      /** Static reference to the log. */
69      private static final Log LOG = CmsLog.getLog(CmsMultiMessages.class);
70  
71      /** A cache for the messages to prevent multiple lookups in many bundles. */
72      private Map   m_messageCache;
73  
74      /** List of resource bundles from the installed modules. */
75      private List   m_messages;
76  
77      /**
78       * Constructor for creating a new messages object initialized with the given locale.<p>
79       * 
80       * @param locale the locale to use for localization of the messages
81       */
82      public CmsMultiMessages(Locale   locale) {
83  
84          super();
85          // set the bundle name and the locale
86          setBundleName(CmsMultiMessages.MULTI_BUNDLE_NAME);
87          setLocale(locale);
88          // generate array for the messages        
89          m_messages = new ArrayList  ();
90          // use "old" Hashtable since it is the most efficient synchronized HashMap implementation
91          m_messageCache = new Hashtable  ();
92      }
93  
94      /**
95       * Adds a bundle instance to this multi message bundle.<p>
96       * 
97       * The added bundle will be localized with the locale of this multi message bundle.<p>
98       * 
99       * @param bundle the bundle instance to add
100      */
101     public void addBundle(I_CmsMessageBundle bundle) {
102 
103         // add the localized bundle to the messages
104         addMessages(bundle.getBundle(getLocale()));
105     }
106 
107     /**
108      * Adds a messages instance to this multi message bundle.<p> 
109      * 
110      * The messages instance should have been initialized with the same locale as this multi bundle,
111      * if not, the locale of the messages instance is automatically replaced. However, this will not work 
112      * if the added messages instance is in face also of type <code>{@link CmsMultiMessages}</code>.<p>
113      * 
114      * @param messages the messages instance to add
115      * 
116      * @throws CmsIllegalArgumentException if the locale of the given <code>{@link CmsMultiMessages}</code> does not match the locale of this multi messages
117      */
118     public void addMessages(CmsMessages messages) throws CmsIllegalArgumentException {
119 
120         Locale   locale = messages.getLocale();
121         if (!getLocale().equals(locale)) {
122             // not the same locale, try to change the locale if this is a simple CmsMessage object
123             if (!(messages instanceof CmsMultiMessages)) {
124                 // match locale of multi bundle
125                 String   bundleName = messages.getBundleName();
126                 messages = new CmsMessages(bundleName, getLocale());
127             } else {
128                 // multi bundles with wrong locales can't be added this way
129                 throw new CmsIllegalArgumentException(Messages.get().container(
130                     Messages.ERR_MULTIMSG_LOCALE_DOES_NOT_MATCH_2,
131                     messages.getLocale(),
132                     getLocale()));
133             }
134         }
135         if (!m_messages.contains(messages)) {
136             if ((m_messageCache != null) && (m_messageCache.size() > 0)) {
137                 // cache has already been used, must flush because of newly added keys
138                 m_messageCache = new Hashtable  ();
139             }
140             m_messages.add(messages);
141         }
142     }
143 
144     /**
145      * Adds a list a messages instances to this multi message bundle.<p> 
146      * 
147      * @param messages the messages instance to add
148      */
149     public void addMessages(List   messages) {
150 
151         if (messages == null) {
152             throw new CmsIllegalArgumentException(Messages.get().container(Messages.ERR_MULTIMSG_EMPTY_LIST_0));
153         }
154 
155         Iterator   i = messages.iterator();
156         while (i.hasNext()) {
157             addMessages((CmsMessages)i.next());
158         }
159     }
160 
161     /**
162      * Returns the list of all individual message objects in this multi message instance.<p>
163      * 
164      * @return the list of all individual message objects in this multi message instance
165      */
166     public List   getMessages() {
167 
168         return m_messages;
169     }
170 
171     /**
172      * @see org.opencms.i18n.CmsMessages#getString(java.lang.String)
173      */
174     public String   getString(String   keyName) {
175 
176         return resolveKey(keyName);
177     }
178 
179     /**
180      * @see org.opencms.i18n.CmsMessages#isInitialized()
181      */
182     public boolean isInitialized() {
183 
184         return (m_messages != null) && !m_messages.isEmpty();
185     }
186 
187     /**
188      * @see org.opencms.i18n.CmsMessages#key(java.lang.String, boolean)
189      */
190     public String   key(String   keyName, boolean allowNull) {
191 
192         // special implementation since we uses several bundles for the messages
193         String   result = resolveKey(keyName);
194         if ((result == null) && !allowNull) {
195             result = formatUnknownKey(keyName);
196         }
197         return result;
198     }
199 
200     /**
201      * Returns the localized resource string for a given message key,
202      * checking the workplace default resources and all module bundles.<p>
203      * 
204      * If the key was not found, <code>null</code> is returned.<p>
205      * 
206      * @param keyName the key for the desired string 
207      * @return the resource string for the given key or null if not found
208      */
209     private String   resolveKey(String   keyName) {
210 
211         if (LOG.isDebugEnabled()) {
212             LOG.debug(Messages.get().getBundle().key(Messages.LOG_RESOLVE_MESSAGE_KEY_1, keyName));
213         }
214 
215         String   result = (String  )m_messageCache.get(keyName);
216         if (result == NULL_STRING) {
217             // key was already checked and not found   
218             return null;
219         }
220         if (result == null) {
221             // so far not in the cache
222             for (int i = 0; (result == null) && (i < m_messages.size()); i++) {
223                 try {
224                     result = ((CmsMessages)m_messages.get(i)).getString(keyName);
225                     // if no exception is thrown here we have found the result
226                 } catch (CmsMessageException e) {
227                     // can usually be ignored
228                     if (LOG.isDebugEnabled()) {
229                         LOG.debug(e.getMessage(), e);
230                     }
231                 }
232             }
233         } else {
234             // result was found in cache
235             if (LOG.isDebugEnabled()) {
236                 LOG.debug(Messages.get().getBundle().key(Messages.LOG_MESSAGE_KEY_FOUND_CACHED_2, keyName, result));
237             }
238             return result;
239         }
240         if (result == null) {
241             // key was not found in "regular" bundle as well as module messages
242             if (LOG.isDebugEnabled()) {
243                 LOG.debug(Messages.get().getBundle().key(Messages.LOG_MESSAGE_KEY_NOT_FOUND_1, keyName));
244             }
245             // ensure null values are also cached
246             m_messageCache.put(keyName, NULL_STRING);
247         } else {
248             // optional debug output
249             if (LOG.isDebugEnabled()) {
250                 LOG.debug(Messages.get().getBundle().key(Messages.LOG_MESSAGE_KEY_FOUND_2, keyName, result));
251             }
252             // cache the result
253             m_messageCache.put(keyName, result);
254         }
255         // return the result        
256         return result;
257     }
258 }
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