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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.lang3;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Locale;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

/**
 * 

Operations to assist when working with a {@link Locale}.

* *

This class tries to handle {@code null} input gracefully. * An exception will not be thrown for a {@code null} input. * Each method documents its behaviour in more detail.

* * @since 2.2 */ public class LocaleUtils { /** Concurrent map of language locales by country. */ private static final ConcurrentMap> cLanguagesByCountry = new ConcurrentHashMap<>(); /** Concurrent map of country locales by language. */ private static final ConcurrentMap> cCountriesByLanguage = new ConcurrentHashMap<>(); /** *

{@code LocaleUtils} instances should NOT be constructed in standard programming. * Instead, the class should be used as {@code LocaleUtils.toLocale("en_GB");}.

* *

This constructor is public to permit tools that require a JavaBean instance * to operate.

*/ public LocaleUtils() { super(); } //----------------------------------------------------------------------- /** *

Converts a String to a Locale.

* *

This method takes the string format of a locale and creates the * locale object from it.

* *
     *   LocaleUtils.toLocale("")           = new Locale("", "")
     *   LocaleUtils.toLocale("en")         = new Locale("en", "")
     *   LocaleUtils.toLocale("en_GB")      = new Locale("en", "GB")
     *   LocaleUtils.toLocale("en_001")     = new Locale("en", "001")
     *   LocaleUtils.toLocale("en_GB_xxx")  = new Locale("en", "GB", "xxx")   (#)
     * 
* *

(#) The behaviour of the JDK variant constructor changed between JDK1.3 and JDK1.4. * In JDK1.3, the constructor upper cases the variant, in JDK1.4, it doesn't. * Thus, the result from getVariant() may vary depending on your JDK.

* *

This method validates the input strictly. * The language code must be lowercase. * The country code must be uppercase. * The separator must be an underscore. * The length must be correct. *

* * @param str the locale String to convert, null returns null * @return a Locale, null if null input * @throws IllegalArgumentException if the string is an invalid format * @see Locale#forLanguageTag(String) */ public static Locale toLocale(final String str) { if (str == null) { return null; } if (str.isEmpty()) { // LANG-941 - JDK 8 introduced an empty locale where all fields are blank return new Locale(StringUtils.EMPTY, StringUtils.EMPTY); } if (str.contains("#")) { // LANG-879 - Cannot handle Java 7 script & extensions throw new IllegalArgumentException("Invalid locale format: " + str); } final int len = str.length(); if (len < 2) { throw new IllegalArgumentException("Invalid locale format: " + str); } final char ch0 = str.charAt(0); if (ch0 == '_') { if (len < 3) { throw new IllegalArgumentException("Invalid locale format: " + str); } final char ch1 = str.charAt(1); final char ch2 = str.charAt(2); if (!Character.isUpperCase(ch1) || !Character.isUpperCase(ch2)) { throw new IllegalArgumentException("Invalid locale format: " + str); } if (len == 3) { return new Locale(StringUtils.EMPTY, str.substring(1, 3)); } if (len < 5) { throw new IllegalArgumentException("Invalid locale format: " + str); } if (str.charAt(3) != '_') { throw new IllegalArgumentException("Invalid locale format: " + str); } return new Locale(StringUtils.EMPTY, str.substring(1, 3), str.substring(4)); } return parseLocale(str); } /** * Tries to parse a locale from the given String. * * @param str the String to parse a locale from. * @return a Locale instance parsed from the given String. * @throws IllegalArgumentException if the given String can not be parsed. */ private static Locale parseLocale(final String str) { if (isISO639LanguageCode(str)) { return new Locale(str); } final String[] segments = str.split("_", -1); final String language = segments[0]; if (segments.length == 2) { final String country = segments[1]; if (isISO639LanguageCode(language) && isISO3166CountryCode(country) || isNumericAreaCode(country)) { return new Locale(language, country); } } else if (segments.length == 3) { final String country = segments[1]; final String variant = segments[2]; if (isISO639LanguageCode(language) && (country.isEmpty() || isISO3166CountryCode(country) || isNumericAreaCode(country)) && !variant.isEmpty()) { return new Locale(language, country, variant); } } throw new IllegalArgumentException("Invalid locale format: " + str); } /** * Checks whether the given String is a ISO 639 compliant language code. * * @param str the String to check. * @return true, if the given String is a ISO 639 compliant language code. */ private static boolean isISO639LanguageCode(final String str) { return StringUtils.isAllLowerCase(str) && (str.length() == 2 || str.length() == 3); } /** * Checks whether the given String is a ISO 3166 alpha-2 country code. * * @param str the String to check * @return true, is the given String is a ISO 3166 compliant country code. */ private static boolean isISO3166CountryCode(final String str) { return StringUtils.isAllUpperCase(str) && str.length() == 2; } /** * Checks whether the given String is a UN M.49 numeric area code. * * @param str the String to check * @return true, is the given String is a UN M.49 numeric area code. */ private static boolean isNumericAreaCode(final String str) { return StringUtils.isNumeric(str) && str.length() == 3; } //----------------------------------------------------------------------- /** *

Obtains the list of locales to search through when performing * a locale search.

* *
     * localeLookupList(Locale("fr","CA","xxx"))
     *   = [Locale("fr","CA","xxx"), Locale("fr","CA"), Locale("fr")]
     * 
* * @param locale the locale to start from * @return the unmodifiable list of Locale objects, 0 being locale, not null */ public static List localeLookupList(final Locale locale) { return localeLookupList(locale, locale); } //----------------------------------------------------------------------- /** *

Obtains the list of locales to search through when performing * a locale search.

* *
     * localeLookupList(Locale("fr", "CA", "xxx"), Locale("en"))
     *   = [Locale("fr","CA","xxx"), Locale("fr","CA"), Locale("fr"), Locale("en"]
     * 
* *

The result list begins with the most specific locale, then the * next more general and so on, finishing with the default locale. * The list will never contain the same locale twice.

* * @param locale the locale to start from, null returns empty list * @param defaultLocale the default locale to use if no other is found * @return the unmodifiable list of Locale objects, 0 being locale, not null */ public static List localeLookupList(final Locale locale, final Locale defaultLocale) { final List list = new ArrayList<>(4); if (locale != null) { list.add(locale); if (!locale.getVariant().isEmpty()) { list.add(new Locale(locale.getLanguage(), locale.getCountry())); } if (!locale.getCountry().isEmpty()) { list.add(new Locale(locale.getLanguage(), StringUtils.EMPTY)); } if (!list.contains(defaultLocale)) { list.add(defaultLocale); } } return Collections.unmodifiableList(list); } //----------------------------------------------------------------------- /** *

Obtains an unmodifiable list of installed locales.

* *

This method is a wrapper around {@link Locale#getAvailableLocales()}. * It is more efficient, as the JDK method must create a new array each * time it is called.

* * @return the unmodifiable list of available locales */ public static List availableLocaleList() { return SyncAvoid.AVAILABLE_LOCALE_LIST; } //----------------------------------------------------------------------- /** *

Obtains an unmodifiable set of installed locales.

* *

This method is a wrapper around {@link Locale#getAvailableLocales()}. * It is more efficient, as the JDK method must create a new array each * time it is called.

* * @return the unmodifiable set of available locales */ public static Set availableLocaleSet() { return SyncAvoid.AVAILABLE_LOCALE_SET; } //----------------------------------------------------------------------- /** *

Checks if the locale specified is in the list of available locales.

* * @param locale the Locale object to check if it is available * @return true if the locale is a known locale */ public static boolean isAvailableLocale(final Locale locale) { return availableLocaleList().contains(locale); } //----------------------------------------------------------------------- /** *

Obtains the list of languages supported for a given country.

* *

This method takes a country code and searches to find the * languages available for that country. Variant locales are removed.

* * @param countryCode the 2 letter country code, null returns empty * @return an unmodifiable List of Locale objects, not null */ public static List languagesByCountry(final String countryCode) { if (countryCode == null) { return Collections.emptyList(); } List langs = cLanguagesByCountry.get(countryCode); if (langs == null) { langs = new ArrayList<>(); final List locales = availableLocaleList(); for (final Locale locale : locales) { if (countryCode.equals(locale.getCountry()) && locale.getVariant().isEmpty()) { langs.add(locale); } } langs = Collections.unmodifiableList(langs); cLanguagesByCountry.putIfAbsent(countryCode, langs); langs = cLanguagesByCountry.get(countryCode); } return langs; } //----------------------------------------------------------------------- /** *

Obtains the list of countries supported for a given language.

* *

This method takes a language code and searches to find the * countries available for that language. Variant locales are removed.

* * @param languageCode the 2 letter language code, null returns empty * @return an unmodifiable List of Locale objects, not null */ public static List countriesByLanguage(final String languageCode) { if (languageCode == null) { return Collections.emptyList(); } List countries = cCountriesByLanguage.get(languageCode); if (countries == null) { countries = new ArrayList<>(); final List locales = availableLocaleList(); for (final Locale locale : locales) { if (languageCode.equals(locale.getLanguage()) && !locale.getCountry().isEmpty() && locale.getVariant().isEmpty()) { countries.add(locale); } } countries = Collections.unmodifiableList(countries); cCountriesByLanguage.putIfAbsent(languageCode, countries); countries = cCountriesByLanguage.get(languageCode); } return countries; } //----------------------------------------------------------------------- // class to avoid synchronization (Init on demand) static class SyncAvoid { /** Unmodifiable list of available locales. */ private static final List AVAILABLE_LOCALE_LIST; /** Unmodifiable set of available locales. */ private static final Set AVAILABLE_LOCALE_SET; static { final List list = new ArrayList<>(Arrays.asList(Locale.getAvailableLocales())); // extra safe AVAILABLE_LOCALE_LIST = Collections.unmodifiableList(list); AVAILABLE_LOCALE_SET = Collections.unmodifiableSet(new HashSet<>(list)); } } }




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