001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.commons.lang3;
018
019 import java.util.ArrayList;
020 import java.util.Arrays;
021 import java.util.Collections;
022 import java.util.HashSet;
023 import java.util.List;
024 import java.util.Locale;
025 import java.util.Set;
026 import java.util.concurrent.ConcurrentHashMap;
027 import java.util.concurrent.ConcurrentMap;
028
029 /**
030 * <p>Operations to assist when working with a {@link Locale}.</p>
031 *
032 * <p>This class tries to handle {@code null} input gracefully.
033 * An exception will not be thrown for a {@code null} input.
034 * Each method documents its behaviour in more detail.</p>
035 *
036 * @since 2.2
037 * @version $Id: LocaleUtils.java 1090563 2011-04-09 11:00:10Z sebb $
038 */
039 public class LocaleUtils {
040
041 /** Concurrent map of language locales by country. */
042 private static final ConcurrentMap<String, List<Locale>> cLanguagesByCountry =
043 new ConcurrentHashMap<String, List<Locale>>();
044
045 /** Concurrent map of country locales by language. */
046 private static final ConcurrentMap<String, List<Locale>> cCountriesByLanguage =
047 new ConcurrentHashMap<String, List<Locale>>();
048
049 /**
050 * <p>{@code LocaleUtils} instances should NOT be constructed in standard programming.
051 * Instead, the class should be used as {@code LocaleUtils.toLocale("en_GB");}.</p>
052 *
053 * <p>This constructor is public to permit tools that require a JavaBean instance
054 * to operate.</p>
055 */
056 public LocaleUtils() {
057 super();
058 }
059
060 //-----------------------------------------------------------------------
061 /**
062 * <p>Converts a String to a Locale.</p>
063 *
064 * <p>This method takes the string format of a locale and creates the
065 * locale object from it.</p>
066 *
067 * <pre>
068 * LocaleUtils.toLocale("en") = new Locale("en", "")
069 * LocaleUtils.toLocale("en_GB") = new Locale("en", "GB")
070 * LocaleUtils.toLocale("en_GB_xxx") = new Locale("en", "GB", "xxx") (#)
071 * </pre>
072 *
073 * <p>(#) The behaviour of the JDK variant constructor changed between JDK1.3 and JDK1.4.
074 * In JDK1.3, the constructor upper cases the variant, in JDK1.4, it doesn't.
075 * Thus, the result from getVariant() may vary depending on your JDK.</p>
076 *
077 * <p>This method validates the input strictly.
078 * The language code must be lowercase.
079 * The country code must be uppercase.
080 * The separator must be an underscore.
081 * The length must be correct.
082 * </p>
083 *
084 * @param str the locale String to convert, null returns null
085 * @return a Locale, null if null input
086 * @throws IllegalArgumentException if the string is an invalid format
087 */
088 public static Locale toLocale(String str) {
089 if (str == null) {
090 return null;
091 }
092 int len = str.length();
093 if (len != 2 && len != 5 && len < 7) {
094 throw new IllegalArgumentException("Invalid locale format: " + str);
095 }
096 char ch0 = str.charAt(0);
097 char ch1 = str.charAt(1);
098 if (ch0 < 'a' || ch0 > 'z' || ch1 < 'a' || ch1 > 'z') {
099 throw new IllegalArgumentException("Invalid locale format: " + str);
100 }
101 if (len == 2) {
102 return new Locale(str, "");
103 } else {
104 if (str.charAt(2) != '_') {
105 throw new IllegalArgumentException("Invalid locale format: " + str);
106 }
107 char ch3 = str.charAt(3);
108 if (ch3 == '_') {
109 return new Locale(str.substring(0, 2), "", str.substring(4));
110 }
111 char ch4 = str.charAt(4);
112 if (ch3 < 'A' || ch3 > 'Z' || ch4 < 'A' || ch4 > 'Z') {
113 throw new IllegalArgumentException("Invalid locale format: " + str);
114 }
115 if (len == 5) {
116 return new Locale(str.substring(0, 2), str.substring(3, 5));
117 } else {
118 if (str.charAt(5) != '_') {
119 throw new IllegalArgumentException("Invalid locale format: " + str);
120 }
121 return new Locale(str.substring(0, 2), str.substring(3, 5), str.substring(6));
122 }
123 }
124 }
125
126 //-----------------------------------------------------------------------
127 /**
128 * <p>Obtains the list of locales to search through when performing
129 * a locale search.</p>
130 *
131 * <pre>
132 * localeLookupList(Locale("fr","CA","xxx"))
133 * = [Locale("fr","CA","xxx"), Locale("fr","CA"), Locale("fr")]
134 * </pre>
135 *
136 * @param locale the locale to start from
137 * @return the unmodifiable list of Locale objects, 0 being locale, not null
138 */
139 public static List<Locale> localeLookupList(Locale locale) {
140 return localeLookupList(locale, locale);
141 }
142
143 //-----------------------------------------------------------------------
144 /**
145 * <p>Obtains the list of locales to search through when performing
146 * a locale search.</p>
147 *
148 * <pre>
149 * localeLookupList(Locale("fr", "CA", "xxx"), Locale("en"))
150 * = [Locale("fr","CA","xxx"), Locale("fr","CA"), Locale("fr"), Locale("en"]
151 * </pre>
152 *
153 * <p>The result list begins with the most specific locale, then the
154 * next more general and so on, finishing with the default locale.
155 * The list will never contain the same locale twice.</p>
156 *
157 * @param locale the locale to start from, null returns empty list
158 * @param defaultLocale the default locale to use if no other is found
159 * @return the unmodifiable list of Locale objects, 0 being locale, not null
160 */
161 public static List<Locale> localeLookupList(Locale locale, Locale defaultLocale) {
162 List<Locale> list = new ArrayList<Locale>(4);
163 if (locale != null) {
164 list.add(locale);
165 if (locale.getVariant().length() > 0) {
166 list.add(new Locale(locale.getLanguage(), locale.getCountry()));
167 }
168 if (locale.getCountry().length() > 0) {
169 list.add(new Locale(locale.getLanguage(), ""));
170 }
171 if (list.contains(defaultLocale) == false) {
172 list.add(defaultLocale);
173 }
174 }
175 return Collections.unmodifiableList(list);
176 }
177
178 //-----------------------------------------------------------------------
179 /**
180 * <p>Obtains an unmodifiable list of installed locales.</p>
181 *
182 * <p>This method is a wrapper around {@link Locale#getAvailableLocales()}.
183 * It is more efficient, as the JDK method must create a new array each
184 * time it is called.</p>
185 *
186 * @return the unmodifiable list of available locales
187 */
188 public static List<Locale> availableLocaleList() {
189 return SyncAvoid.AVAILABLE_LOCALE_LIST;
190 }
191
192 //-----------------------------------------------------------------------
193 /**
194 * <p>Obtains an unmodifiable set of installed locales.</p>
195 *
196 * <p>This method is a wrapper around {@link Locale#getAvailableLocales()}.
197 * It is more efficient, as the JDK method must create a new array each
198 * time it is called.</p>
199 *
200 * @return the unmodifiable set of available locales
201 */
202 public static Set<Locale> availableLocaleSet() {
203 return SyncAvoid.AVAILABLE_LOCALE_SET;
204 }
205
206 //-----------------------------------------------------------------------
207 /**
208 * <p>Checks if the locale specified is in the list of available locales.</p>
209 *
210 * @param locale the Locale object to check if it is available
211 * @return true if the locale is a known locale
212 */
213 public static boolean isAvailableLocale(Locale locale) {
214 return availableLocaleList().contains(locale);
215 }
216
217 //-----------------------------------------------------------------------
218 /**
219 * <p>Obtains the list of languages supported for a given country.</p>
220 *
221 * <p>This method takes a country code and searches to find the
222 * languages available for that country. Variant locales are removed.</p>
223 *
224 * @param countryCode the 2 letter country code, null returns empty
225 * @return an unmodifiable List of Locale objects, not null
226 */
227 public static List<Locale> languagesByCountry(String countryCode) {
228 if (countryCode == null) {
229 return Collections.emptyList();
230 }
231 List<Locale> langs = cLanguagesByCountry.get(countryCode);
232 if (langs == null) {
233 langs = new ArrayList<Locale>();
234 List<Locale> locales = availableLocaleList();
235 for (int i = 0; i < locales.size(); i++) {
236 Locale locale = locales.get(i);
237 if (countryCode.equals(locale.getCountry()) &&
238 locale.getVariant().length() == 0) {
239 langs.add(locale);
240 }
241 }
242 langs = Collections.unmodifiableList(langs);
243 cLanguagesByCountry.putIfAbsent(countryCode, langs);
244 langs = cLanguagesByCountry.get(countryCode);
245 }
246 return langs;
247 }
248
249 //-----------------------------------------------------------------------
250 /**
251 * <p>Obtains the list of countries supported for a given language.</p>
252 *
253 * <p>This method takes a language code and searches to find the
254 * countries available for that language. Variant locales are removed.</p>
255 *
256 * @param languageCode the 2 letter language code, null returns empty
257 * @return an unmodifiable List of Locale objects, not null
258 */
259 public static List<Locale> countriesByLanguage(String languageCode) {
260 if (languageCode == null) {
261 return Collections.emptyList();
262 }
263 List<Locale> countries = cCountriesByLanguage.get(languageCode);
264 if (countries == null) {
265 countries = new ArrayList<Locale>();
266 List<Locale> locales = availableLocaleList();
267 for (int i = 0; i < locales.size(); i++) {
268 Locale locale = locales.get(i);
269 if (languageCode.equals(locale.getLanguage()) &&
270 locale.getCountry().length() != 0 &&
271 locale.getVariant().length() == 0) {
272 countries.add(locale);
273 }
274 }
275 countries = Collections.unmodifiableList(countries);
276 cCountriesByLanguage.putIfAbsent(languageCode, countries);
277 countries = cCountriesByLanguage.get(languageCode);
278 }
279 return countries;
280 }
281
282 //-----------------------------------------------------------------------
283 // class to avoid synchronization
284 static class SyncAvoid {
285 /** Unmodifiable list of available locales. */
286 private static List<Locale> AVAILABLE_LOCALE_LIST;
287 /** Unmodifiable set of available locales. */
288 private static Set<Locale> AVAILABLE_LOCALE_SET;
289
290 static {
291 List<Locale> list = new ArrayList<Locale>(Arrays.asList(Locale.getAvailableLocales())); // extra safe
292 AVAILABLE_LOCALE_LIST = Collections.unmodifiableList(list);
293 AVAILABLE_LOCALE_SET = Collections.unmodifiableSet(new HashSet<Locale>(availableLocaleList()));
294 }
295 }
296
297 }