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.lang;
18
19 import java.util.ArrayList;
20 import java.util.Arrays;
21 import java.util.Collections;
22 import java.util.HashMap;
23 import java.util.HashSet;
24 import java.util.List;
25 import java.util.Locale;
26 import java.util.Map;
27 import java.util.Set;
28
29 /**
30 * <p>Operations to assist when working with a {@link Locale}.</p>
31 *
32 * <p>This class tries to handle <code>null</code> input gracefully.
33 * An exception will not be thrown for a <code>null</code> input.
34 * Each method documents its behaviour in more detail.</p>
35 *
36 * @author Stephen Colebourne
37 * @since 2.2
38 * @version $Id: LocaleUtils.java 534277 2007-05-01 23:50:01Z bayard $
39 */
40 public class LocaleUtils {
41
42 /** Unmodifiable list of available locales. */
43 private static final List cAvailableLocaleList;
44 /** Unmodifiable set of available locales. */
45 private static Set cAvailableLocaleSet;
46 /** Unmodifiable map of language locales by country. */
47 private static final Map cLanguagesByCountry = Collections.synchronizedMap(new HashMap());
48 /** Unmodifiable map of country locales by language. */
49 private static final Map cCountriesByLanguage = Collections.synchronizedMap(new HashMap());
50 static {
51 List list = Arrays.asList(Locale.getAvailableLocales());
52 cAvailableLocaleList = Collections.unmodifiableList(list);
53 }
54
55 /**
56 * <p><code>LocaleUtils</code> instances should NOT be constructed in standard programming.
57 * Instead, the class should be used as <code>LocaleUtils.toLocale("en_GB");</code>.</p>
58 *
59 * <p>This constructor is public to permit tools that require a JavaBean instance
60 * to operate.</p>
61 */
62 public LocaleUtils() {
63 super();
64 }
65
66 //-----------------------------------------------------------------------
67 /**
68 * <p>Converts a String to a Locale.</p>
69 *
70 * <p>This method takes the string format of a locale and creates the
71 * locale object from it.</p>
72 *
73 * <pre>
74 * LocaleUtils.toLocale("en") = new Locale("en", "")
75 * LocaleUtils.toLocale("en_GB") = new Locale("en", "GB")
76 * LocaleUtils.toLocale("en_GB_xxx") = new Locale("en", "GB", "xxx") (#)
77 * </pre>
78 *
79 * <p>(#) The behaviour of the JDK variant constructor changed between JDK1.3 and JDK1.4.
80 * In JDK1.3, the constructor upper cases the variant, in JDK1.4, it doesn't.
81 * Thus, the result from getVariant() may vary depending on your JDK.</p>
82 *
83 * <p>This method validates the input strictly.
84 * The language code must be lowercase.
85 * The country code must be uppercase.
86 * The separator must be an underscore.
87 * The length must be correct.
88 * </p>
89 *
90 * @param str the locale String to convert, null returns null
91 * @return a Locale, null if null input
92 * @throws IllegalArgumentException if the string is an invalid format
93 */
94 public static Locale toLocale(String str) {
95 if (str == null) {
96 return null;
97 }
98 int len = str.length();
99 if (len != 2 && len != 5 && len < 7) {
100 throw new IllegalArgumentException("Invalid locale format: " + str);
101 }
102 char ch0 = str.charAt(0);
103 char ch1 = str.charAt(1);
104 if (ch0 < 'a' || ch0 > 'z' || ch1 < 'a' || ch1 > 'z') {
105 throw new IllegalArgumentException("Invalid locale format: " + str);
106 }
107 if (len == 2) {
108 return new Locale(str, "");
109 } else {
110 if (str.charAt(2) != '_') {
111 throw new IllegalArgumentException("Invalid locale format: " + str);
112 }
113 char ch3 = str.charAt(3);
114 if (ch3 == '_') {
115 return new Locale(str.substring(0, 2), "", str.substring(4));
116 }
117 char ch4 = str.charAt(4);
118 if (ch3 < 'A' || ch3 > 'Z' || ch4 < 'A' || ch4 > 'Z') {
119 throw new IllegalArgumentException("Invalid locale format: " + str);
120 }
121 if (len == 5) {
122 return new Locale(str.substring(0, 2), str.substring(3, 5));
123 } else {
124 if (str.charAt(5) != '_') {
125 throw new IllegalArgumentException("Invalid locale format: " + str);
126 }
127 return new Locale(str.substring(0, 2), str.substring(3, 5), str.substring(6));
128 }
129 }
130 }
131
132 //-----------------------------------------------------------------------
133 /**
134 * <p>Obtains the list of locales to search through when performing
135 * a locale search.</p>
136 *
137 * <pre>
138 * localeLookupList(Locale("fr","CA","xxx"))
139 * = [Locale("fr","CA","xxx"), Locale("fr","CA"), Locale("fr")]
140 * </pre>
141 *
142 * @param locale the locale to start from
143 * @return the unmodifiable list of Locale objects, 0 being locale, never null
144 */
145 public static List localeLookupList(Locale locale) {
146 return localeLookupList(locale, locale);
147 }
148
149 //-----------------------------------------------------------------------
150 /**
151 * <p>Obtains the list of locales to search through when performing
152 * a locale search.</p>
153 *
154 * <pre>
155 * localeLookupList(Locale("fr", "CA", "xxx"), Locale("en"))
156 * = [Locale("fr","CA","xxx"), Locale("fr","CA"), Locale("fr"), Locale("en"]
157 * </pre>
158 *
159 * <p>The result list begins with the most specific locale, then the
160 * next more general and so on, finishing with the default locale.
161 * The list will never contain the same locale twice.</p>
162 *
163 * @param locale the locale to start from, null returns empty list
164 * @param defaultLocale the default locale to use if no other is found
165 * @return the unmodifiable list of Locale objects, 0 being locale, never null
166 */
167 public static List localeLookupList(Locale locale, Locale defaultLocale) {
168 List list = new ArrayList(4);
169 if (locale != null) {
170 list.add(locale);
171 if (locale.getVariant().length() > 0) {
172 list.add(new Locale(locale.getLanguage(), locale.getCountry()));
173 }
174 if (locale.getCountry().length() > 0) {
175 list.add(new Locale(locale.getLanguage(), ""));
176 }
177 if (list.contains(defaultLocale) == false) {
178 list.add(defaultLocale);
179 }
180 }
181 return Collections.unmodifiableList(list);
182 }
183
184 //-----------------------------------------------------------------------
185 /**
186 * <p>Obtains an unmodifiable list of installed locales.</p>
187 *
188 * <p>This method is a wrapper around {@link Locale#getAvailableLocales()}.
189 * It is more efficient, as the JDK method must create a new array each
190 * time it is called.</p>
191 *
192 * @return the unmodifiable list of available locales
193 */
194 public static List availableLocaleList() {
195 return cAvailableLocaleList;
196 }
197
198 //-----------------------------------------------------------------------
199 /**
200 * <p>Obtains an unmodifiable set of installed locales.</p>
201 *
202 * <p>This method is a wrapper around {@link Locale#getAvailableLocales()}.
203 * It is more efficient, as the JDK method must create a new array each
204 * time it is called.</p>
205 *
206 * @return the unmodifiable set of available locales
207 */
208 public static Set availableLocaleSet() {
209 Set set = cAvailableLocaleSet;
210 if (set == null) {
211 set = new HashSet(availableLocaleList());
212 set = Collections.unmodifiableSet(set);
213 cAvailableLocaleSet = set;
214 }
215 return set;
216 }
217
218 //-----------------------------------------------------------------------
219 /**
220 * <p>Checks if the locale specified is in the list of available locales.</p>
221 *
222 * @param locale the Locale object to check if it is available
223 * @return true if the locale is a known locale
224 */
225 public static boolean isAvailableLocale(Locale locale) {
226 return availableLocaleList().contains(locale);
227 }
228
229 //-----------------------------------------------------------------------
230 /**
231 * <p>Obtains the list of languages supported for a given country.</p>
232 *
233 * <p>This method takes a country code and searches to find the
234 * languages available for that country. Variant locales are removed.</p>
235 *
236 * @param countryCode the 2 letter country code, null returns empty
237 * @return an unmodifiable List of Locale objects, never null
238 */
239 public static List languagesByCountry(String countryCode) {
240 List langs = (List) cLanguagesByCountry.get(countryCode); //syncd
241 if (langs == null) {
242 if (countryCode != null) {
243 langs = new ArrayList();
244 List locales = availableLocaleList();
245 for (int i = 0; i < locales.size(); i++) {
246 Locale locale = (Locale) locales.get(i);
247 if (countryCode.equals(locale.getCountry()) &&
248 locale.getVariant().length() == 0) {
249 langs.add(locale);
250 }
251 }
252 langs = Collections.unmodifiableList(langs);
253 } else {
254 langs = Collections.EMPTY_LIST;
255 }
256 cLanguagesByCountry.put(countryCode, langs); //syncd
257 }
258 return langs;
259 }
260
261 //-----------------------------------------------------------------------
262 /**
263 * <p>Obtains the list of countries supported for a given language.</p>
264 *
265 * <p>This method takes a language code and searches to find the
266 * countries available for that language. Variant locales are removed.</p>
267 *
268 * @param languageCode the 2 letter language code, null returns empty
269 * @return an unmodifiable List of Locale objects, never null
270 */
271 public static List countriesByLanguage(String languageCode) {
272 List countries = (List) cCountriesByLanguage.get(languageCode); //syncd
273 if (countries == null) {
274 if (languageCode != null) {
275 countries = new ArrayList();
276 List locales = availableLocaleList();
277 for (int i = 0; i < locales.size(); i++) {
278 Locale locale = (Locale) locales.get(i);
279 if (languageCode.equals(locale.getLanguage()) &&
280 locale.getCountry().length() != 0 &&
281 locale.getVariant().length() == 0) {
282 countries.add(locale);
283 }
284 }
285 countries = Collections.unmodifiableList(countries);
286 } else {
287 countries = Collections.EMPTY_LIST;
288 }
289 cCountriesByLanguage.put(languageCode, countries); //syncd
290 }
291 return countries;
292 }
293
294 }