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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    * 
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   * 
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.apache.commons.lang3;
18  
19  import java.util.ArrayList;
20  import java.util.Arrays;
21  import java.util.Collections;
22  import java.util.HashSet;
23  import java.util.List;
24  import java.util.Locale;
25  import java.util.Set;
26  import java.util.concurrent.ConcurrentHashMap;
27  import java.util.concurrent.ConcurrentMap;
28  
29  /**
30   * <p>Operations to assist when working with a {@link Locale}.</p>
31   *
32   * <p>This class tries to handle {@code null} input gracefully.
33   * An exception will not be thrown for a {@code null} input.
34   * Each method documents its behaviour in more detail.</p>
35   *
36   * @since 2.2
37   * @version $Id: LocaleUtils.java 1565235 2014-02-06 13:31:43Z sebb $
38   */
39  public class LocaleUtils {
40  
41      /** Concurrent map of language locales by country. */
42      private static final ConcurrentMap<String, List<Locale>> cLanguagesByCountry = 
43          new ConcurrentHashMap<String, List<Locale>>();
44  
45      /** Concurrent map of country locales by language. */
46      private static final ConcurrentMap<String, List<Locale>> cCountriesByLanguage = 
47          new ConcurrentHashMap<String, List<Locale>>();
48  
49      /**
50       * <p>{@code LocaleUtils} instances should NOT be constructed in standard programming.
51       * Instead, the class should be used as {@code LocaleUtils.toLocale("en_GB");}.</p>
52       *
53       * <p>This constructor is public to permit tools that require a JavaBean instance
54       * to operate.</p>
55       */
56      public LocaleUtils() {
57        super();
58      }
59  
60      //-----------------------------------------------------------------------
61      /**
62       * <p>Converts a String to a Locale.</p>
63       *
64       * <p>This method takes the string format of a locale and creates the
65       * locale object from it.</p>
66       *
67       * <pre>
68       *   LocaleUtils.toLocale("")           = new Locale("", "")
69       *   LocaleUtils.toLocale("en")         = new Locale("en", "")
70       *   LocaleUtils.toLocale("en_GB")      = new Locale("en", "GB")
71       *   LocaleUtils.toLocale("en_GB_xxx")  = new Locale("en", "GB", "xxx")   (#)
72       * </pre>
73       *
74       * <p>(#) The behaviour of the JDK variant constructor changed between JDK1.3 and JDK1.4.
75       * In JDK1.3, the constructor upper cases the variant, in JDK1.4, it doesn't.
76       * Thus, the result from getVariant() may vary depending on your JDK.</p>
77       *
78       * <p>This method validates the input strictly.
79       * The language code must be lowercase.
80       * The country code must be uppercase.
81       * The separator must be an underscore.
82       * The length must be correct.
83       * </p>
84       *
85       * @param str  the locale String to convert, null returns null
86       * @return a Locale, null if null input
87       * @throws IllegalArgumentException if the string is an invalid format
88       * @see Locale#forLanguageTag(String)
89       */
90      public static Locale toLocale(final String str) {
91          if (str == null) {
92              return null;
93          }
94          if (str.isEmpty()) { // LANG-941 - JDK 8 introduced an empty locale where all fields are blank
95              return new Locale("", "");
96          }
97          if (str.contains("#")) { // LANG-879 - Cannot handle Java 7 script & extensions
98              throw new IllegalArgumentException("Invalid locale format: " + str);
99          }
100         final int len = str.length();
101         if (len < 2) {
102             throw new IllegalArgumentException("Invalid locale format: " + str);
103         }
104         final char ch0 = str.charAt(0);
105         if (ch0 == '_') {
106             if (len < 3) {
107                 throw new IllegalArgumentException("Invalid locale format: " + str);
108             }
109             final char ch1 = str.charAt(1);
110             final char ch2 = str.charAt(2);
111             if (!Character.isUpperCase(ch1) || !Character.isUpperCase(ch2)) {
112                 throw new IllegalArgumentException("Invalid locale format: " + str);
113             }
114             if (len == 3) {
115                 return new Locale("", str.substring(1, 3));
116             }
117             if (len < 5) {
118                 throw new IllegalArgumentException("Invalid locale format: " + str);
119             }
120             if (str.charAt(3) != '_') {
121                 throw new IllegalArgumentException("Invalid locale format: " + str);
122             }
123             return new Locale("", str.substring(1, 3), str.substring(4));
124         }
125         
126         String[] split = str.split("_", -1);
127         int occurrences = split.length -1;
128         switch (occurrences) {
129             case 0:
130                 if (StringUtils.isAllLowerCase(str) && (len == 2 || len == 3)) {
131                     return new Locale(str);
132                 } else {
133                     throw new IllegalArgumentException("Invalid locale format: " + str);
134                 }
135                 
136             case 1:
137                 if (StringUtils.isAllLowerCase(split[0]) &&
138                     (split[0].length() == 2 || split[0].length() == 3) &&
139                      split[1].length() == 2 && StringUtils.isAllUpperCase(split[1])) {
140                     return new Locale(split[0], split[1]);
141                 } else {
142                     throw new IllegalArgumentException("Invalid locale format: " + str);
143                 }
144 
145             case 2:
146                 if (StringUtils.isAllLowerCase(split[0]) && 
147                     (split[0].length() == 2 || split[0].length() == 3) &&
148                     (split[1].length() == 0 || (split[1].length() == 2 && StringUtils.isAllUpperCase(split[1]))) &&
149                      split[2].length() > 0) {
150                     return new Locale(split[0], split[1], split[2]);
151                 }
152 
153                 //$FALL-THROUGH$
154             default:
155                 throw new IllegalArgumentException("Invalid locale format: " + str);
156         }
157     }
158 
159     //-----------------------------------------------------------------------
160     /**
161      * <p>Obtains the list of locales to search through when performing
162      * a locale search.</p>
163      *
164      * <pre>
165      * localeLookupList(Locale("fr","CA","xxx"))
166      *   = [Locale("fr","CA","xxx"), Locale("fr","CA"), Locale("fr")]
167      * </pre>
168      *
169      * @param locale  the locale to start from
170      * @return the unmodifiable list of Locale objects, 0 being locale, not null
171      */
172     public static List<Locale> localeLookupList(final Locale locale) {
173         return localeLookupList(locale, locale);
174     }
175 
176     //-----------------------------------------------------------------------
177     /**
178      * <p>Obtains the list of locales to search through when performing
179      * a locale search.</p>
180      *
181      * <pre>
182      * localeLookupList(Locale("fr", "CA", "xxx"), Locale("en"))
183      *   = [Locale("fr","CA","xxx"), Locale("fr","CA"), Locale("fr"), Locale("en"]
184      * </pre>
185      *
186      * <p>The result list begins with the most specific locale, then the
187      * next more general and so on, finishing with the default locale.
188      * The list will never contain the same locale twice.</p>
189      *
190      * @param locale  the locale to start from, null returns empty list
191      * @param defaultLocale  the default locale to use if no other is found
192      * @return the unmodifiable list of Locale objects, 0 being locale, not null
193      */
194     public static List<Locale> localeLookupList(final Locale locale, final Locale defaultLocale) {
195         final List<Locale> list = new ArrayList<Locale>(4);
196         if (locale != null) {
197             list.add(locale);
198             if (locale.getVariant().length() > 0) {
199                 list.add(new Locale(locale.getLanguage(), locale.getCountry()));
200             }
201             if (locale.getCountry().length() > 0) {
202                 list.add(new Locale(locale.getLanguage(), ""));
203             }
204             if (list.contains(defaultLocale) == false) {
205                 list.add(defaultLocale);
206             }
207         }
208         return Collections.unmodifiableList(list);
209     }
210 
211     //-----------------------------------------------------------------------
212     /**
213      * <p>Obtains an unmodifiable list of installed locales.</p>
214      * 
215      * <p>This method is a wrapper around {@link Locale#getAvailableLocales()}.
216      * It is more efficient, as the JDK method must create a new array each
217      * time it is called.</p>
218      *
219      * @return the unmodifiable list of available locales
220      */
221     public static List<Locale> availableLocaleList() {
222         return SyncAvoid.AVAILABLE_LOCALE_LIST;
223     }
224 
225     //-----------------------------------------------------------------------
226     /**
227      * <p>Obtains an unmodifiable set of installed locales.</p>
228      * 
229      * <p>This method is a wrapper around {@link Locale#getAvailableLocales()}.
230      * It is more efficient, as the JDK method must create a new array each
231      * time it is called.</p>
232      *
233      * @return the unmodifiable set of available locales
234      */
235     public static Set<Locale> availableLocaleSet() {
236         return SyncAvoid.AVAILABLE_LOCALE_SET;
237     }
238 
239     //-----------------------------------------------------------------------
240     /**
241      * <p>Checks if the locale specified is in the list of available locales.</p>
242      *
243      * @param locale the Locale object to check if it is available
244      * @return true if the locale is a known locale
245      */
246     public static boolean isAvailableLocale(final Locale locale) {
247         return availableLocaleList().contains(locale);
248     }
249 
250     //-----------------------------------------------------------------------
251     /**
252      * <p>Obtains the list of languages supported for a given country.</p>
253      *
254      * <p>This method takes a country code and searches to find the
255      * languages available for that country. Variant locales are removed.</p>
256      *
257      * @param countryCode  the 2 letter country code, null returns empty
258      * @return an unmodifiable List of Locale objects, not null
259      */
260     public static List<Locale> languagesByCountry(final String countryCode) {
261         if (countryCode == null) {
262             return Collections.emptyList();
263         }
264         List<Locale> langs = cLanguagesByCountry.get(countryCode);
265         if (langs == null) {
266             langs = new ArrayList<Locale>();
267             final List<Locale> locales = availableLocaleList();
268             for (int i = 0; i < locales.size(); i++) {
269                 final Locale locale = locales.get(i);
270                 if (countryCode.equals(locale.getCountry()) &&
271                         locale.getVariant().isEmpty()) {
272                     langs.add(locale);
273                 }
274             }
275             langs = Collections.unmodifiableList(langs);
276             cLanguagesByCountry.putIfAbsent(countryCode, langs);
277             langs = cLanguagesByCountry.get(countryCode);
278         }
279         return langs;
280     }
281 
282     //-----------------------------------------------------------------------
283     /**
284      * <p>Obtains the list of countries supported for a given language.</p>
285      * 
286      * <p>This method takes a language code and searches to find the
287      * countries available for that language. Variant locales are removed.</p>
288      *
289      * @param languageCode  the 2 letter language code, null returns empty
290      * @return an unmodifiable List of Locale objects, not null
291      */
292     public static List<Locale> countriesByLanguage(final String languageCode) {
293         if (languageCode == null) {
294             return Collections.emptyList();
295         }
296         List<Locale> countries = cCountriesByLanguage.get(languageCode);
297         if (countries == null) {
298             countries = new ArrayList<Locale>();
299             final List<Locale> locales = availableLocaleList();
300             for (int i = 0; i < locales.size(); i++) {
301                 final Locale locale = locales.get(i);
302                 if (languageCode.equals(locale.getLanguage()) &&
303                         locale.getCountry().length() != 0 &&
304                         locale.getVariant().isEmpty()) {
305                     countries.add(locale);
306                 }
307             }
308             countries = Collections.unmodifiableList(countries);
309             cCountriesByLanguage.putIfAbsent(languageCode, countries);
310             countries = cCountriesByLanguage.get(languageCode);
311         }
312         return countries;
313     }
314 
315     //-----------------------------------------------------------------------
316     // class to avoid synchronization (Init on demand)
317     static class SyncAvoid {
318         /** Unmodifiable list of available locales. */
319         private static final List<Locale> AVAILABLE_LOCALE_LIST;
320         /** Unmodifiable set of available locales. */
321         private static final Set<Locale> AVAILABLE_LOCALE_SET;
322         
323         static {
324             final List<Locale> list = new ArrayList<Locale>(Arrays.asList(Locale.getAvailableLocales()));  // extra safe
325             AVAILABLE_LOCALE_LIST = Collections.unmodifiableList(list);
326             AVAILABLE_LOCALE_SET = Collections.unmodifiableSet(new HashSet<Locale>(list));
327         }
328     }
329 
330 }