    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 */
    017package org.apache.commons.lang3;
    018
    019import java.util.ArrayList;
    020import java.util.Arrays;
    021import java.util.Collections;
    022import java.util.HashSet;
    023import java.util.List;
    024import java.util.Locale;
    025import java.util.Set;
    026import java.util.concurrent.ConcurrentHashMap;
    027import 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 behavior in more detail.</p>
    035 *
    036 * @since 2.2
    037 */
    038public class LocaleUtils {
    039
    040    // class to avoid synchronization (Init on demand)
    041    static class SyncAvoid {
    042        /** Unmodifiable list of available locales. */
    043        private static final List<Locale> AVAILABLE_LOCALE_LIST;
    044        /** Unmodifiable set of available locales. */
    045        private static final Set<Locale> AVAILABLE_LOCALE_SET;
    046
    047        static {
    048            final List<Locale> list = new ArrayList<>(Arrays.asList(Locale.getAvailableLocales()));  // extra safe
    049            AVAILABLE_LOCALE_LIST = Collections.unmodifiableList(list);
    050            AVAILABLE_LOCALE_SET = Collections.unmodifiableSet(new HashSet<>(list));
    051        }
    052    }
    053
    054    /** Concurrent map of language locales by country. */
    055    private static final ConcurrentMap<String, List<Locale>> cLanguagesByCountry =
    056        new ConcurrentHashMap<>();
    057
    058    /** Concurrent map of country locales by language. */
    059    private static final ConcurrentMap<String, List<Locale>> cCountriesByLanguage =
    060        new ConcurrentHashMap<>();
    061
    062    /**
    063     * <p>Obtains an unmodifiable list of installed locales.</p>
    064     *
    065     * <p>This method is a wrapper around {@link Locale#getAvailableLocales()}.
    066     * It is more efficient, as the JDK method must create a new array each
    067     * time it is called.</p>
    068     *
    069     * @return the unmodifiable list of available locales
    070     */
    071    public static List<Locale> availableLocaleList() {
    072        return SyncAvoid.AVAILABLE_LOCALE_LIST;
    073    }
    074
    075    /**
    076     * <p>Obtains an unmodifiable set of installed locales.</p>
    077     *
    078     * <p>This method is a wrapper around {@link Locale#getAvailableLocales()}.
    079     * It is more efficient, as the JDK method must create a new array each
    080     * time it is called.</p>
    081     *
    082     * @return the unmodifiable set of available locales
    083     */
    084    public static Set<Locale> availableLocaleSet() {
    085        return SyncAvoid.AVAILABLE_LOCALE_SET;
    086    }
    087
    088    /**
    089     * <p>Obtains the list of countries supported for a given language.</p>
    090     *
    091     * <p>This method takes a language code and searches to find the
    092     * countries available for that language. Variant locales are removed.</p>
    093     *
    094     * @param languageCode  the 2 letter language code, null returns empty
    095     * @return an unmodifiable List of Locale objects, not null
    096     */
    097    public static List<Locale> countriesByLanguage(final String languageCode) {
    098        if (languageCode == null) {
    099            return Collections.emptyList();
    100        }
    101        List<Locale> countries = cCountriesByLanguage.get(languageCode);
    102        if (countries == null) {
    103            countries = new ArrayList<>();
    104            final List<Locale> locales = availableLocaleList();
    105            for (final Locale locale : locales) {
    106                if (languageCode.equals(locale.getLanguage()) &&
    107                        !locale.getCountry().isEmpty() &&
    108                    locale.getVariant().isEmpty()) {
    109                    countries.add(locale);
    110                }
    111            }
    112            countries = Collections.unmodifiableList(countries);
    113            cCountriesByLanguage.putIfAbsent(languageCode, countries);
    114            countries = cCountriesByLanguage.get(languageCode);
    115        }
    116        return countries;
    117    }
    118
    119    /**
    120     * <p>Checks if the locale specified is in the list of available locales.</p>
    121     *
    122     * @param locale the Locale object to check if it is available
    123     * @return true if the locale is a known locale
    124     */
    125    public static boolean isAvailableLocale(final Locale locale) {
    126        return availableLocaleList().contains(locale);
    127    }
    128
    129    /**
    130     * Checks whether the given String is a ISO 3166 alpha-2 country code.
    131     *
    132     * @param str the String to check
    133     * @return true, is the given String is a ISO 3166 compliant country code.
    134     */
    135    private static boolean isISO3166CountryCode(final String str) {
    136        return StringUtils.isAllUpperCase(str) && str.length() == 2;
    137    }
    138
    139    /**
    140     * Checks whether the given String is a ISO 639 compliant language code.
    141     *
    142     * @param str the String to check.
    143     * @return true, if the given String is a ISO 639 compliant language code.
    144     */
    145    private static boolean isISO639LanguageCode(final String str) {
    146        return StringUtils.isAllLowerCase(str) && (str.length() == 2 || str.length() == 3);
    147    }
    148
    149    /**
    150     * Checks whether the given String is a UN M.49 numeric area code.
    151     *
    152     * @param str the String to check
    153     * @return true, is the given String is a UN M.49 numeric area code.
    154     */
    155    private static boolean isNumericAreaCode(final String str) {
    156        return StringUtils.isNumeric(str) && str.length() == 3;
    157    }
    158
    159    /**
    160     * <p>Obtains the list of languages supported for a given country.</p>
    161     *
    162     * <p>This method takes a country code and searches to find the
    163     * languages available for that country. Variant locales are removed.</p>
    164     *
    165     * @param countryCode  the 2 letter country code, null returns empty
    166     * @return an unmodifiable List of Locale objects, not null
    167     */
    168    public static List<Locale> languagesByCountry(final String countryCode) {
    169        if (countryCode == null) {
    170            return Collections.emptyList();
    171        }
    172        List<Locale> langs = cLanguagesByCountry.get(countryCode);
    173        if (langs == null) {
    174            langs = new ArrayList<>();
    175            final List<Locale> locales = availableLocaleList();
    176            for (final Locale locale : locales) {
    177                if (countryCode.equals(locale.getCountry()) &&
    178                    locale.getVariant().isEmpty()) {
    179                    langs.add(locale);
    180                }
    181            }
    182            langs = Collections.unmodifiableList(langs);
    183            cLanguagesByCountry.putIfAbsent(countryCode, langs);
    184            langs = cLanguagesByCountry.get(countryCode);
    185        }
    186        return langs;
    187    }
    188
    189    /**
    190     * <p>Obtains the list of locales to search through when performing
    191     * a locale search.</p>
    192     *
    193     * <pre>
    194     * localeLookupList(Locale("fr", "CA", "xxx"))
    195     *   = [Locale("fr", "CA", "xxx"), Locale("fr", "CA"), Locale("fr")]
    196     * </pre>
    197     *
    198     * @param locale  the locale to start from
    199     * @return the unmodifiable list of Locale objects, 0 being locale, not null
    200     */
    201    public static List<Locale> localeLookupList(final Locale locale) {
    202        return localeLookupList(locale, locale);
    203    }
    204
    205    /**
    206     * <p>Obtains the list of locales to search through when performing
    207     * a locale search.</p>
    208     *
    209     * <pre>
    210     * localeLookupList(Locale("fr", "CA", "xxx"), Locale("en"))
    211     *   = [Locale("fr", "CA", "xxx"), Locale("fr", "CA"), Locale("fr"), Locale("en"]
    212     * </pre>
    213     *
    214     * <p>The result list begins with the most specific locale, then the
    215     * next more general and so on, finishing with the default locale.
    216     * The list will never contain the same locale twice.</p>
    217     *
    218     * @param locale  the locale to start from, null returns empty list
    219     * @param defaultLocale  the default locale to use if no other is found
    220     * @return the unmodifiable list of Locale objects, 0 being locale, not null
    221     */
    222    public static List<Locale> localeLookupList(final Locale locale, final Locale defaultLocale) {
    223        final List<Locale> list = new ArrayList<>(4);
    224        if (locale != null) {
    225            list.add(locale);
    226            if (!locale.getVariant().isEmpty()) {
    227                list.add(new Locale(locale.getLanguage(), locale.getCountry()));
    228            }
    229            if (!locale.getCountry().isEmpty()) {
    230                list.add(new Locale(locale.getLanguage(), StringUtils.EMPTY));
    231            }
    232            if (!list.contains(defaultLocale)) {
    233                list.add(defaultLocale);
    234            }
    235        }
    236        return Collections.unmodifiableList(list);
    237    }
    238
    239    /**
    240     * Tries to parse a locale from the given String.
    241     *
    242     * @param str the String to parse a locale from.
    243     * @return a Locale instance parsed from the given String.
    244     * @throws IllegalArgumentException if the given String can not be parsed.
    245     */
    246    private static Locale parseLocale(final String str) {
    247        if (isISO639LanguageCode(str)) {
    248            return new Locale(str);
    249        }
    250
    251        final String[] segments = str.split("_", -1);
    252        final String language = segments[0];
    253        if (segments.length == 2) {
    254            final String country = segments[1];
    255            if (isISO639LanguageCode(language) && isISO3166CountryCode(country) ||
    256                    isNumericAreaCode(country)) {
    257                return new Locale(language, country);
    258            }
    259        } else if (segments.length == 3) {
    260            final String country = segments[1];
    261            final String variant = segments[2];
    262            if (isISO639LanguageCode(language) &&
    263                    (country.isEmpty() || isISO3166CountryCode(country) || isNumericAreaCode(country)) &&
    264                    !variant.isEmpty()) {
    265                return new Locale(language, country, variant);
    266            }
    267        }
    268        throw new IllegalArgumentException("Invalid locale format: " + str);
    269    }
    270
    271    /**
    272     * Returns the given locale if non-{@code null}, otherwise {@link Locale#getDefault()}.
    273     *
    274     * @param locale a locale or {@code null}.
    275     * @return the given locale if non-{@code null}, otherwise {@link Locale#getDefault()}.
    276     * @since 3.12.0
    277     */
    278    public static Locale toLocale(final Locale locale) {
    279        return locale != null ? locale : Locale.getDefault();
    280    }
    281
    282    /**
    283     * <p>Converts a String to a Locale.</p>
    284     *
    285     * <p>This method takes the string format of a locale and creates the
    286     * locale object from it.</p>
    287     *
    288     * <pre>
    289     *   LocaleUtils.toLocale("")           = new Locale("", "")
    290     *   LocaleUtils.toLocale("en")         = new Locale("en", "")
    291     *   LocaleUtils.toLocale("en_GB")      = new Locale("en", "GB")
    292     *   LocaleUtils.toLocale("en_001")     = new Locale("en", "001")
    293     *   LocaleUtils.toLocale("en_GB_xxx")  = new Locale("en", "GB", "xxx")   (#)
    294     * </pre>
    295     *
    296     * <p>(#) The behavior of the JDK variant constructor changed between JDK1.3 and JDK1.4.
    297     * In JDK1.3, the constructor upper cases the variant, in JDK1.4, it doesn't.
    298     * Thus, the result from getVariant() may vary depending on your JDK.</p>
    299     *
    300     * <p>This method validates the input strictly.
    301     * The language code must be lowercase.
    302     * The country code must be uppercase.
    303     * The separator must be an underscore.
    304     * The length must be correct.
    305     * </p>
    306     *
    307     * @param str  the locale String to convert, null returns null
    308     * @return a Locale, null if null input
    309     * @throws IllegalArgumentException if the string is an invalid format
    310     * @see Locale#forLanguageTag(String)
    311     */
    312    public static Locale toLocale(final String str) {
    313        if (str == null) {
    314            return null;
    315        }
    316        if (str.isEmpty()) { // LANG-941 - JDK 8 introduced an empty locale where all fields are blank
    317            return new Locale(StringUtils.EMPTY, StringUtils.EMPTY);
    318        }
    319        if (str.contains("#")) { // LANG-879 - Cannot handle Java 7 script & extensions
    320            throw new IllegalArgumentException("Invalid locale format: " + str);
    321        }
    322        final int len = str.length();
    323        if (len < 2) {
    324            throw new IllegalArgumentException("Invalid locale format: " + str);
    325        }
    326        final char ch0 = str.charAt(0);
    327        if (ch0 == '_') {
    328            if (len < 3) {
    329                throw new IllegalArgumentException("Invalid locale format: " + str);
    330            }
    331            final char ch1 = str.charAt(1);
    332            final char ch2 = str.charAt(2);
    333            if (!Character.isUpperCase(ch1) || !Character.isUpperCase(ch2)) {
    334                throw new IllegalArgumentException("Invalid locale format: " + str);
    335            }
    336            if (len == 3) {
    337                return new Locale(StringUtils.EMPTY, str.substring(1, 3));
    338            }
    339            if (len < 5) {
    340                throw new IllegalArgumentException("Invalid locale format: " + str);
    341            }
    342            if (str.charAt(3) != '_') {
    343                throw new IllegalArgumentException("Invalid locale format: " + str);
    344            }
    345            return new Locale(StringUtils.EMPTY, str.substring(1, 3), str.substring(4));
    346        }
    347
    348        return parseLocale(str);
    349    }
    350
    351    /**
    352     * <p>{@code LocaleUtils} instances should NOT be constructed in standard programming.
    353     * Instead, the class should be used as {@code LocaleUtils.toLocale("en_GB");}.</p>
    354     *
    355     * <p>This constructor is public to permit tools that require a JavaBean instance
    356     * to operate.</p>
    357     */
    358    public LocaleUtils() {
    359    }
    360
    361}