    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;
    028import java.util.function.Predicate;
    029import java.util.stream.Collectors;
    030
    031/**
    032 * Operations to assist when working with a {@link Locale}.
    033 *
    034 * <p>This class tries to handle {@code null} input gracefully.
    035 * An exception will not be thrown for a {@code null} input.
    036 * Each method documents its behavior in more detail.</p>
    037 *
    038 * @since 2.2
    039 */
    040public class LocaleUtils {
    041
    042    // class to avoid synchronization (Init on demand)
    043    static class SyncAvoid {
    044        /** Unmodifiable list of available locales. */
    045        private static final List<Locale> AVAILABLE_LOCALE_LIST;
    046        /** Unmodifiable set of available locales. */
    047        private static final Set<Locale> AVAILABLE_LOCALE_SET;
    048
    049        static {
    050            final List<Locale> list = new ArrayList<>(Arrays.asList(Locale.getAvailableLocales()));  // extra safe
    051            AVAILABLE_LOCALE_LIST = Collections.unmodifiableList(list);
    052            AVAILABLE_LOCALE_SET = Collections.unmodifiableSet(new HashSet<>(list));
    053        }
    054    }
    055    private static final char UNDERSCORE = '_';
    056    private static final String UNDETERMINED = "und";
    057
    058    private static final char DASH = '-';
    059
    060    /** Concurrent map of language locales by country. */
    061    private static final ConcurrentMap<String, List<Locale>> cLanguagesByCountry =
    062        new ConcurrentHashMap<>();
    063
    064    /** Concurrent map of country locales by language. */
    065    private static final ConcurrentMap<String, List<Locale>> cCountriesByLanguage =
    066        new ConcurrentHashMap<>();
    067
    068    /**
    069     * Obtains an unmodifiable list of installed locales.
    070     *
    071     * <p>This method is a wrapper around {@link Locale#getAvailableLocales()}.
    072     * It is more efficient, as the JDK method must create a new array each
    073     * time it is called.</p>
    074     *
    075     * @return the unmodifiable list of available locales
    076     */
    077    public static List<Locale> availableLocaleList() {
    078        return SyncAvoid.AVAILABLE_LOCALE_LIST;
    079    }
    080
    081    private static List<Locale> availableLocaleList(final Predicate<Locale> predicate) {
    082        return availableLocaleList().stream().filter(predicate).collect(Collectors.toList());
    083    }
    084
    085    /**
    086     * Obtains an unmodifiable set of installed locales.
    087     *
    088     * <p>This method is a wrapper around {@link Locale#getAvailableLocales()}.
    089     * It is more efficient, as the JDK method must create a new array each
    090     * time it is called.</p>
    091     *
    092     * @return the unmodifiable set of available locales
    093     */
    094    public static Set<Locale> availableLocaleSet() {
    095        return SyncAvoid.AVAILABLE_LOCALE_SET;
    096    }
    097
    098    /**
    099     * Obtains the list of countries supported for a given language.
    100     *
    101     * <p>This method takes a language code and searches to find the
    102     * countries available for that language. Variant locales are removed.</p>
    103     *
    104     * @param languageCode  the 2 letter language code, null returns empty
    105     * @return an unmodifiable List of Locale objects, not null
    106     */
    107    public static List<Locale> countriesByLanguage(final String languageCode) {
    108        if (languageCode == null) {
    109            return Collections.emptyList();
    110        }
    111        return cCountriesByLanguage.computeIfAbsent(languageCode, lc -> Collections.unmodifiableList(
    112            availableLocaleList(locale -> languageCode.equals(locale.getLanguage()) && !locale.getCountry().isEmpty() && locale.getVariant().isEmpty())));
    113    }
    114
    115    /**
    116     * Checks if the locale specified is in the set of available locales.
    117     *
    118     * @param locale the Locale object to check if it is available
    119     * @return true if the locale is a known locale
    120     */
    121    public static boolean isAvailableLocale(final Locale locale) {
    122        return availableLocaleSet().contains(locale);
    123    }
    124
    125    /**
    126     * Checks whether the given String is a ISO 3166 alpha-2 country code.
    127     *
    128     * @param str the String to check
    129     * @return true, is the given String is a ISO 3166 compliant country code.
    130     */
    131    private static boolean isISO3166CountryCode(final String str) {
    132        return StringUtils.isAllUpperCase(str) && str.length() == 2;
    133    }
    134
    135    /**
    136     * Checks whether the given String is a ISO 639 compliant language code.
    137     *
    138     * @param str the String to check.
    139     * @return true, if the given String is a ISO 639 compliant language code.
    140     */
    141    private static boolean isISO639LanguageCode(final String str) {
    142        return StringUtils.isAllLowerCase(str) && (str.length() == 2 || str.length() == 3);
    143    }
    144
    145    /**
    146     * Tests whether a Locale's language is undetermined.
    147     * <p>
    148     * A Locale's language tag is undetermined if it's value is {@code "und"}. If a language is empty, or not well-formed (for example, "a" or"e2"), it will be
    149     * equal to {@code "und"}.
    150     * </p>
    151     *
    152     * @param locale the locale to test.
    153     * @return whether a Locale's language is undetermined.
    154     * @see Locale#toLanguageTag()
    155     * @since 3.14.0
    156     */
    157    public static boolean isLanguageUndetermined(final Locale locale) {
    158        return locale == null || UNDETERMINED.equals(locale.toLanguageTag());
    159    }
    160
    161    /**
    162     * Checks whether the given String is a UN M.49 numeric area code.
    163     *
    164     * @param str the String to check
    165     * @return true, is the given String is a UN M.49 numeric area code.
    166     */
    167    private static boolean isNumericAreaCode(final String str) {
    168        return StringUtils.isNumeric(str) && str.length() == 3;
    169    }
    170
    171    /**
    172     * Obtains the list of languages supported for a given country.
    173     *
    174     * <p>This method takes a country code and searches to find the
    175     * languages available for that country. Variant locales are removed.</p>
    176     *
    177     * @param countryCode  the 2-letter country code, null returns empty
    178     * @return an unmodifiable List of Locale objects, not null
    179     */
    180    public static List<Locale> languagesByCountry(final String countryCode) {
    181        if (countryCode == null) {
    182            return Collections.emptyList();
    183        }
    184        return cLanguagesByCountry.computeIfAbsent(countryCode,
    185            k -> Collections.unmodifiableList(availableLocaleList(locale -> countryCode.equals(locale.getCountry()) && locale.getVariant().isEmpty())));
    186    }
    187
    188    /**
    189     * Obtains the list of locales to search through when performing
    190     * a locale search.
    191     *
    192     * <pre>
    193     * localeLookupList(Locale("fr", "CA", "xxx"))
    194     *   = [Locale("fr", "CA", "xxx"), Locale("fr", "CA"), Locale("fr")]
    195     * </pre>
    196     *
    197     * @param locale  the locale to start from
    198     * @return the unmodifiable list of Locale objects, 0 being locale, not null
    199     */
    200    public static List<Locale> localeLookupList(final Locale locale) {
    201        return localeLookupList(locale, locale);
    202    }
    203
    204    /**
    205     * Obtains the list of locales to search through when performing
    206     * a locale search.
    207     *
    208     * <pre>
    209     * localeLookupList(Locale("fr", "CA", "xxx"), Locale("en"))
    210     *   = [Locale("fr", "CA", "xxx"), Locale("fr", "CA"), Locale("fr"), Locale("en"]
    211     * </pre>
    212     *
    213     * <p>The result list begins with the most specific locale, then the
    214     * next more general and so on, finishing with the default locale.
    215     * The list will never contain the same locale twice.</p>
    216     *
    217     * @param locale  the locale to start from, null returns empty list
    218     * @param defaultLocale  the default locale to use if no other is found
    219     * @return the unmodifiable list of Locale objects, 0 being locale, not null
    220     */
    221    public static List<Locale> localeLookupList(final Locale locale, final Locale defaultLocale) {
    222        final List<Locale> list = new ArrayList<>(4);
    223        if (locale != null) {
    224            list.add(locale);
    225            if (!locale.getVariant().isEmpty()) {
    226                list.add(new Locale(locale.getLanguage(), locale.getCountry()));
    227            }
    228            if (!locale.getCountry().isEmpty()) {
    229                list.add(new Locale(locale.getLanguage(), StringUtils.EMPTY));
    230            }
    231            if (!list.contains(defaultLocale)) {
    232                list.add(defaultLocale);
    233            }
    234        }
    235        return Collections.unmodifiableList(list);
    236    }
    237
    238    /**
    239     * Tries to parse a locale from the given String.
    240     *
    241     * @param str the String to parse a locale from.
    242     * @return a Locale instance parsed from the given String.
    243     * @throws IllegalArgumentException if the given String can not be parsed.
    244     */
    245    private static Locale parseLocale(final String str) {
    246        if (isISO639LanguageCode(str)) {
    247            return new Locale(str);
    248        }
    249
    250        final String[] segments = str.indexOf(UNDERSCORE) != -1
    251            ? str.split(String.valueOf(UNDERSCORE), -1)
    252            : str.split(String.valueOf(DASH), -1);
    253        final String language = segments[0];
    254        if (segments.length == 2) {
    255            final String country = segments[1];
    256            if (isISO639LanguageCode(language) && isISO3166CountryCode(country) ||
    257                    isNumericAreaCode(country)) {
    258                return new Locale(language, country);
    259            }
    260        } else if (segments.length == 3) {
    261            final String country = segments[1];
    262            final String variant = segments[2];
    263            if (isISO639LanguageCode(language) &&
    264                    (country.isEmpty() || isISO3166CountryCode(country) || isNumericAreaCode(country)) &&
    265                    !variant.isEmpty()) {
    266                return new Locale(language, country, variant);
    267            }
    268        }
    269        throw new IllegalArgumentException("Invalid locale format: " + str);
    270    }
    271
    272    /**
    273     * Returns the given locale if non-{@code null}, otherwise {@link Locale#getDefault()}.
    274     *
    275     * @param locale a locale or {@code null}.
    276     * @return the given locale if non-{@code null}, otherwise {@link Locale#getDefault()}.
    277     * @since 3.12.0
    278     */
    279    public static Locale toLocale(final Locale locale) {
    280        return locale != null ? locale : Locale.getDefault();
    281    }
    282
    283    /**
    284     * Converts a String to a Locale.
    285     *
    286     * <p>This method takes the string format of a locale and creates the
    287     * locale object from it.</p>
    288     *
    289     * <pre>
    290     *   LocaleUtils.toLocale("")           = new Locale("", "")
    291     *   LocaleUtils.toLocale("en")         = new Locale("en", "")
    292     *   LocaleUtils.toLocale("en_GB")      = new Locale("en", "GB")
    293     *   LocaleUtils.toLocale("en-GB")      = new Locale("en", "GB")
    294     *   LocaleUtils.toLocale("en_001")     = new Locale("en", "001")
    295     *   LocaleUtils.toLocale("en_GB_xxx")  = new Locale("en", "GB", "xxx")   (#)
    296     * </pre>
    297     *
    298     * <p>(#) The behavior of the JDK variant constructor changed between JDK1.3 and JDK1.4.
    299     * In JDK1.3, the constructor upper cases the variant, in JDK1.4, it doesn't.
    300     * Thus, the result from getVariant() may vary depending on your JDK.</p>
    301     *
    302     * <p>This method validates the input strictly.
    303     * The language code must be lowercase.
    304     * The country code must be uppercase.
    305     * The separator must be an underscore or a dash.
    306     * The length must be correct.
    307     * </p>
    308     *
    309     * @param str  the locale String to convert, null returns null
    310     * @return a Locale, null if null input
    311     * @throws IllegalArgumentException if the string is an invalid format
    312     * @see Locale#forLanguageTag(String)
    313     */
    314    public static Locale toLocale(final String str) {
    315        if (str == null) {
    316            // TODO Should this return the default locale?
    317            return null;
    318        }
    319        if (str.isEmpty()) { // LANG-941 - JDK 8 introduced an empty locale where all fields are blank
    320            return new Locale(StringUtils.EMPTY, StringUtils.EMPTY);
    321        }
    322        if (str.contains("#")) { // LANG-879 - Cannot handle Java 7 script & extensions
    323            throw new IllegalArgumentException("Invalid locale format: " + str);
    324        }
    325        final int len = str.length();
    326        if (len < 2) {
    327            throw new IllegalArgumentException("Invalid locale format: " + str);
    328        }
    329        final char ch0 = str.charAt(0);
    330        if (ch0 == UNDERSCORE || ch0 == DASH) {
    331            if (len < 3) {
    332                throw new IllegalArgumentException("Invalid locale format: " + str);
    333            }
    334            final char ch1 = str.charAt(1);
    335            final char ch2 = str.charAt(2);
    336            if (!Character.isUpperCase(ch1) || !Character.isUpperCase(ch2)) {
    337                throw new IllegalArgumentException("Invalid locale format: " + str);
    338            }
    339            if (len == 3) {
    340                return new Locale(StringUtils.EMPTY, str.substring(1, 3));
    341            }
    342            if (len < 5) {
    343                throw new IllegalArgumentException("Invalid locale format: " + str);
    344            }
    345            if (str.charAt(3) != ch0) {
    346                throw new IllegalArgumentException("Invalid locale format: " + str);
    347            }
    348            return new Locale(StringUtils.EMPTY, str.substring(1, 3), str.substring(4));
    349        }
    350
    351        return parseLocale(str);
    352    }
    353
    354    /**
    355     * {@link LocaleUtils} instances should NOT be constructed in standard programming.
    356     * Instead, the class should be used as {@code LocaleUtils.toLocale("en_GB");}.
    357     *
    358     * <p>This constructor is public to permit tools that require a JavaBean instance
    359     * to operate.</p>
    360     */
    361    public LocaleUtils() {
    362    }
    363
    364}