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.HashMap;
023 import java.util.HashSet;
024 import java.util.List;
025 import java.util.Locale;
026 import java.util.Map;
027 import java.util.Set;
028
029 /**
030 * <p>Operations to assist when working with a {@link Locale}.</p>
031 *
032 * <p>This class tries to handle <code>null</code> input gracefully.
033 * An exception will not be thrown for a <code>null</code> input.
034 * Each method documents its behaviour in more detail.</p>
035 *
036 * @author Apache Software Foundation
037 * @since 2.2
038 * @version $Id: LocaleUtils.java 889215 2009-12-10 11:56:38Z bayard $
039 */
040 public class LocaleUtils {
041
042 /** Unmodifiable list of available locales. */
043 //@GuardedBy("this")
044 private static List<Locale> cAvailableLocaleList; // lazily created by availableLocaleList()
045
046 /** Unmodifiable set of available locales. */
047 //@GuardedBy("this")
048 private static Set<Locale> cAvailableLocaleSet; // lazily created by availableLocaleSet()
049
050 /** Unmodifiable map of language locales by country. */
051 private static final Map<String, List<Locale>> cLanguagesByCountry = Collections.synchronizedMap(new HashMap<String, List<Locale>>());
052
053 /** Unmodifiable map of country locales by language. */
054 private static final Map<String, List<Locale>> cCountriesByLanguage = Collections.synchronizedMap(new HashMap<String, List<Locale>>());
055
056 /**
057 * <p><code>LocaleUtils</code> instances should NOT be constructed in standard programming.
058 * Instead, the class should be used as <code>LocaleUtils.toLocale("en_GB");</code>.</p>
059 *
060 * <p>This constructor is public to permit tools that require a JavaBean instance
061 * to operate.</p>
062 */
063 public LocaleUtils() {
064 super();
065 }
066
067 //-----------------------------------------------------------------------
068 /**
069 * <p>Converts a String to a Locale.</p>
070 *
071 * <p>This method takes the string format of a locale and creates the
072 * locale object from it.</p>
073 *
074 * <pre>
075 * LocaleUtils.toLocale("en") = new Locale("en", "")
076 * LocaleUtils.toLocale("en_GB") = new Locale("en", "GB")
077 * LocaleUtils.toLocale("en_GB_xxx") = new Locale("en", "GB", "xxx") (#)
078 * </pre>
079 *
080 * <p>(#) The behaviour of the JDK variant constructor changed between JDK1.3 and JDK1.4.
081 * In JDK1.3, the constructor upper cases the variant, in JDK1.4, it doesn't.
082 * Thus, the result from getVariant() may vary depending on your JDK.</p>
083 *
084 * <p>This method validates the input strictly.
085 * The language code must be lowercase.
086 * The country code must be uppercase.
087 * The separator must be an underscore.
088 * The length must be correct.
089 * </p>
090 *
091 * @param str the locale String to convert, null returns null
092 * @return a Locale, null if null input
093 * @throws IllegalArgumentException if the string is an invalid format
094 */
095 public static Locale toLocale(String str) {
096 if (str == null) {
097 return null;
098 }
099 int len = str.length();
100 if (len != 2 && len != 5 && len < 7) {
101 throw new IllegalArgumentException("Invalid locale format: " + str);
102 }
103 char ch0 = str.charAt(0);
104 char ch1 = str.charAt(1);
105 if (ch0 < 'a' || ch0 > 'z' || ch1 < 'a' || ch1 > 'z') {
106 throw new IllegalArgumentException("Invalid locale format: " + str);
107 }
108 if (len == 2) {
109 return new Locale(str, "");
110 } else {
111 if (str.charAt(2) != '_') {
112 throw new IllegalArgumentException("Invalid locale format: " + str);
113 }
114 char ch3 = str.charAt(3);
115 if (ch3 == '_') {
116 return new Locale(str.substring(0, 2), "", str.substring(4));
117 }
118 char ch4 = str.charAt(4);
119 if (ch3 < 'A' || ch3 > 'Z' || ch4 < 'A' || ch4 > 'Z') {
120 throw new IllegalArgumentException("Invalid locale format: " + str);
121 }
122 if (len == 5) {
123 return new Locale(str.substring(0, 2), str.substring(3, 5));
124 } else {
125 if (str.charAt(5) != '_') {
126 throw new IllegalArgumentException("Invalid locale format: " + str);
127 }
128 return new Locale(str.substring(0, 2), str.substring(3, 5), str.substring(6));
129 }
130 }
131 }
132
133 //-----------------------------------------------------------------------
134 /**
135 * <p>Obtains the list of locales to search through when performing
136 * a locale search.</p>
137 *
138 * <pre>
139 * localeLookupList(Locale("fr","CA","xxx"))
140 * = [Locale("fr","CA","xxx"), Locale("fr","CA"), Locale("fr")]
141 * </pre>
142 *
143 * @param locale the locale to start from
144 * @return the unmodifiable list of Locale objects, 0 being locale, never null
145 */
146 public static List<Locale> localeLookupList(Locale locale) {
147 return localeLookupList(locale, locale);
148 }
149
150 //-----------------------------------------------------------------------
151 /**
152 * <p>Obtains the list of locales to search through when performing
153 * a locale search.</p>
154 *
155 * <pre>
156 * localeLookupList(Locale("fr", "CA", "xxx"), Locale("en"))
157 * = [Locale("fr","CA","xxx"), Locale("fr","CA"), Locale("fr"), Locale("en"]
158 * </pre>
159 *
160 * <p>The result list begins with the most specific locale, then the
161 * next more general and so on, finishing with the default locale.
162 * The list will never contain the same locale twice.</p>
163 *
164 * @param locale the locale to start from, null returns empty list
165 * @param defaultLocale the default locale to use if no other is found
166 * @return the unmodifiable list of Locale objects, 0 being locale, never null
167 */
168 public static List<Locale> localeLookupList(Locale locale, Locale defaultLocale) {
169 List<Locale> list = new ArrayList<Locale>(4);
170 if (locale != null) {
171 list.add(locale);
172 if (locale.getVariant().length() > 0) {
173 list.add(new Locale(locale.getLanguage(), locale.getCountry()));
174 }
175 if (locale.getCountry().length() > 0) {
176 list.add(new Locale(locale.getLanguage(), ""));
177 }
178 if (list.contains(defaultLocale) == false) {
179 list.add(defaultLocale);
180 }
181 }
182 return Collections.unmodifiableList(list);
183 }
184
185 //-----------------------------------------------------------------------
186 /**
187 * <p>Obtains an unmodifiable list of installed locales.</p>
188 *
189 * <p>This method is a wrapper around {@link Locale#getAvailableLocales()}.
190 * It is more efficient, as the JDK method must create a new array each
191 * time it is called.</p>
192 *
193 * @return the unmodifiable list of available locales
194 */
195 public static List<Locale> availableLocaleList() {
196 if(cAvailableLocaleList == null) {
197 initAvailableLocaleList();
198 }
199 return cAvailableLocaleList;
200 }
201
202 /**
203 * Initializes the availableLocaleList. It is separate from availableLocaleList()
204 * to avoid the synchronized block affecting normal use, yet synchronized and
205 * lazy loading to avoid a static block affecting other methods in this class.
206 */
207 private static synchronized void initAvailableLocaleList() {
208 if(cAvailableLocaleList == null) {
209 List<Locale> list = Arrays.asList(Locale.getAvailableLocales());
210 cAvailableLocaleList = Collections.unmodifiableList(list);
211 }
212 }
213
214 //-----------------------------------------------------------------------
215 /**
216 * <p>Obtains an unmodifiable set of installed locales.</p>
217 *
218 * <p>This method is a wrapper around {@link Locale#getAvailableLocales()}.
219 * It is more efficient, as the JDK method must create a new array each
220 * time it is called.</p>
221 *
222 * @return the unmodifiable set of available locales
223 */
224 public static Set<Locale> availableLocaleSet() {
225 if(cAvailableLocaleSet == null) {
226 initAvailableLocaleSet();
227 }
228 return cAvailableLocaleSet;
229 }
230
231 /**
232 * Initializes the availableLocaleSet. It is separate from availableLocaleSet()
233 * to avoid the synchronized block affecting normal use, yet synchronized and
234 * lazy loading to avoid a static block affecting other methods in this class.
235 */
236 private static synchronized void initAvailableLocaleSet() {
237 if(cAvailableLocaleSet == null) {
238 cAvailableLocaleSet = Collections.unmodifiableSet( new HashSet<Locale>(availableLocaleList()) );
239 }
240 }
241
242 //-----------------------------------------------------------------------
243 /**
244 * <p>Checks if the locale specified is in the list of available locales.</p>
245 *
246 * @param locale the Locale object to check if it is available
247 * @return true if the locale is a known locale
248 */
249 public static boolean isAvailableLocale(Locale locale) {
250 return availableLocaleList().contains(locale);
251 }
252
253 //-----------------------------------------------------------------------
254 /**
255 * <p>Obtains the list of languages supported for a given country.</p>
256 *
257 * <p>This method takes a country code and searches to find the
258 * languages available for that country. Variant locales are removed.</p>
259 *
260 * @param countryCode the 2 letter country code, null returns empty
261 * @return an unmodifiable List of Locale objects, never null
262 */
263 public static List<Locale> languagesByCountry(String countryCode) {
264 List<Locale> langs = cLanguagesByCountry.get(countryCode); //syncd
265 if (langs == null) {
266 if (countryCode != null) {
267 langs = new ArrayList<Locale>();
268 List<Locale> locales = availableLocaleList();
269 for (int i = 0; i < locales.size(); i++) {
270 Locale locale = locales.get(i);
271 if (countryCode.equals(locale.getCountry()) &&
272 locale.getVariant().length() == 0) {
273 langs.add(locale);
274 }
275 }
276 langs = Collections.unmodifiableList(langs);
277 } else {
278 langs = Collections.emptyList();
279 }
280 cLanguagesByCountry.put(countryCode, langs); //syncd
281 }
282 return langs;
283 }
284
285 //-----------------------------------------------------------------------
286 /**
287 * <p>Obtains the list of countries supported for a given language.</p>
288 *
289 * <p>This method takes a language code and searches to find the
290 * countries available for that language. Variant locales are removed.</p>
291 *
292 * @param languageCode the 2 letter language code, null returns empty
293 * @return an unmodifiable List of Locale objects, never null
294 */
295 public static List<Locale> countriesByLanguage(String languageCode) {
296 List<Locale> countries = cCountriesByLanguage.get(languageCode); //syncd
297 if (countries == null) {
298 if (languageCode != null) {
299 countries = new ArrayList<Locale>();
300 List<Locale> locales = availableLocaleList();
301 for (int i = 0; i < locales.size(); i++) {
302 Locale locale = locales.get(i);
303 if (languageCode.equals(locale.getLanguage()) &&
304 locale.getCountry().length() != 0 &&
305 locale.getVariant().length() == 0) {
306 countries.add(locale);
307 }
308 }
309 countries = Collections.unmodifiableList(countries);
310 } else {
311 countries = Collections.emptyList();
312 }
313 cCountriesByLanguage.put(languageCode, countries); //syncd
314 }
315 return countries;
316 }
317
318 }