    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 *      https://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.Comparator;
    023import java.util.LinkedHashSet;
    024import java.util.List;
    025import java.util.Locale;
    026import java.util.Set;
    027import java.util.concurrent.ConcurrentHashMap;
    028import java.util.concurrent.ConcurrentMap;
    029import java.util.function.Predicate;
    030import java.util.stream.Collectors;
    031
    032/**
    033 * Operations to assist when working with a {@link Locale}.
    034 *
    035 * <p>This class tries to handle {@code null} input gracefully.
    036 * An exception will not be thrown for a {@code null} input.
    037 * Each method documents its behavior in more detail.</p>
    038 *
    039 * @since 2.2
    040 */
    041public class LocaleUtils {
    042
    043    /**
    044     * Avoids synchronization, inits on demand.
    045     */
    046    private static final class SyncAvoid {
    047
    048        /** Private unmodifiable and sorted list of available locales. */
    049        private static final List<Locale> AVAILABLE_LOCALE_ULIST;
    050
    051        /** Private unmodifiable set of available locales. */
    052        private static final Set<Locale> AVAILABLE_LOCALE_USET;
    053
    054        static {
    055            AVAILABLE_LOCALE_ULIST = Collections
    056                    .unmodifiableList(Arrays.asList(ArraySorter.sort(Locale.getAvailableLocales(), Comparator.comparing(Locale::toString))));
    057            AVAILABLE_LOCALE_USET = Collections.unmodifiableSet(new LinkedHashSet<>(AVAILABLE_LOCALE_ULIST));
    058        }
    059    }
    060
    061    /**
    062     * The underscore character {@code '}{@value}{@code '}.
    063     */
    064    private static final char UNDERSCORE = '_';
    065
    066    /**
    067     * The undetermined language {@value}.
    068     * <p>
    069     * If a language is empty, or not <em>well-formed</am> (for example "a" or "e2"), {@link Locale#toLanguageTag()} will return {@code "und"} (Undetermined).
    070     * </p>
    071     *
    072     * @see Locale#toLanguageTag()
    073     */
    074    private static final String UNDETERMINED = "und";
    075
    076    /**
    077     * The dash character {@code '}{@value}{@code '}.
    078     */
    079    private static final char DASH = '-';
    080
    081    /**
    082     * Concurrent map of language locales by country.
    083     */
    084    private static final ConcurrentMap<String, List<Locale>> cLanguagesByCountry = new ConcurrentHashMap<>();
    085
    086    /**
    087     * Concurrent map of country locales by language.
    088     */
    089    private static final ConcurrentMap<String, List<Locale>> cCountriesByLanguage = new ConcurrentHashMap<>();
    090
    091    /**
    092     * Obtains an unmodifiable and sorted list of installed locales.
    093     *
    094     * <p>This method is a wrapper around {@link Locale#getAvailableLocales()}.
    095     * It is more efficient, as the JDK method must create a new array each
    096     * time it is called.</p>
    097     *
    098     * @return the unmodifiable and sorted list of available locales
    099     */
    100    public static List<Locale> availableLocaleList() {
    101        return SyncAvoid.AVAILABLE_LOCALE_ULIST;
    102    }
    103
    104    private static List<Locale> availableLocaleList(final Predicate<Locale> predicate) {
    105        return availableLocaleList().stream().filter(predicate).collect(Collectors.toList());
    106    }
    107
    108    /**
    109     * Obtains an unmodifiable set of installed locales.
    110     *
    111     * <p>This method is a wrapper around {@link Locale#getAvailableLocales()}.
    112     * It is more efficient, as the JDK method must create a new array each
    113     * time it is called.</p>
    114     *
    115     * @return the unmodifiable set of available locales
    116     */
    117    public static Set<Locale> availableLocaleSet() {
    118        return SyncAvoid.AVAILABLE_LOCALE_USET;
    119    }
    120
    121    /**
    122     * Obtains the list of countries supported for a given language.
    123     *
    124     * <p>This method takes a language code and searches to find the
    125     * countries available for that language. Variant locales are removed.</p>
    126     *
    127     * @param languageCode  the 2 letter language code, null returns empty
    128     * @return an unmodifiable List of Locale objects, not null
    129     */
    130    public static List<Locale> countriesByLanguage(final String languageCode) {
    131        if (languageCode == null) {
    132            return Collections.emptyList();
    133        }
    134        return cCountriesByLanguage.computeIfAbsent(languageCode, lc -> Collections.unmodifiableList(
    135            availableLocaleList(locale -> languageCode.equals(locale.getLanguage()) && !locale.getCountry().isEmpty() && locale.getVariant().isEmpty())));
    136    }
    137
    138    /**
    139     * Checks if the locale specified is in the set of available locales.
    140     *
    141     * @param locale the Locale object to check if it is available
    142     * @return true if the locale is a known locale
    143     */
    144    public static boolean isAvailableLocale(final Locale locale) {
    145        return availableLocaleSet().contains(locale);
    146    }
    147
    148    /**
    149     * Tests whether the given String is a ISO 3166 alpha-2 country code.
    150     *
    151     * @param str the String to check
    152     * @return true, is the given String is a ISO 3166 compliant country code.
    153     */
    154    private static boolean isISO3166CountryCode(final String str) {
    155        return StringUtils.isAllUpperCase(str) && str.length() == 2;
    156    }
    157
    158    /**
    159     * Tests whether the given String is a ISO 639 compliant language code.
    160     *
    161     * @param str the String to check.
    162     * @return true, if the given String is a ISO 639 compliant language code.
    163     */
    164    private static boolean isISO639LanguageCode(final String str) {
    165        return StringUtils.isAllLowerCase(str) && (str.length() == 2 || str.length() == 3);
    166    }
    167
    168    /**
    169     * Tests whether a Locale's language is undetermined.
    170     * <p>
    171     * 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
    172     * equal to {@code "und"}.
    173     * </p>
    174     *
    175     * @param locale the locale to test.
    176     * @return whether a Locale's language is undetermined.
    177     * @see Locale#toLanguageTag()
    178     * @since 3.14.0
    179     */
    180    public static boolean isLanguageUndetermined(final Locale locale) {
    181        return locale == null || UNDETERMINED.equals(locale.toLanguageTag());
    182    }
    183
    184    /**
    185     * TestsNo whether the given String is a UN M.49 numeric area code.
    186     *
    187     * @param str the String to check
    188     * @return true, is the given String is a UN M.49 numeric area code.
    189     */
    190    private static boolean isNumericAreaCode(final String str) {
    191        return StringUtils.isNumeric(str) && str.length() == 3;
    192    }
    193
    194    /**
    195     * Obtains the list of languages supported for a given country.
    196     *
    197     * <p>This method takes a country code and searches to find the
    198     * languages available for that country. Variant locales are removed.</p>
    199     *
    200     * @param countryCode  the 2-letter country code, null returns empty
    201     * @return an unmodifiable List of Locale objects, not null
    202     */
    203    public static List<Locale> languagesByCountry(final String countryCode) {
    204        if (countryCode == null) {
    205            return Collections.emptyList();
    206        }
    207        return cLanguagesByCountry.computeIfAbsent(countryCode,
    208            k -> Collections.unmodifiableList(availableLocaleList(locale -> countryCode.equals(locale.getCountry()) && locale.getVariant().isEmpty())));
    209    }
    210
    211    /**
    212     * Obtains the list of locales to search through when performing
    213     * a locale search.
    214     *
    215     * <pre>
    216     * localeLookupList(Locale("fr", "CA", "xxx"))
    217     *   = [Locale("fr", "CA", "xxx"), Locale("fr", "CA"), Locale("fr")]
    218     * </pre>
    219     *
    220     * @param locale  the locale to start from
    221     * @return the unmodifiable list of Locale objects, 0 being locale, not null
    222     */
    223    public static List<Locale> localeLookupList(final Locale locale) {
    224        return localeLookupList(locale, locale);
    225    }
    226
    227    /**
    228     * Obtains the list of locales to search through when performing
    229     * a locale search.
    230     *
    231     * <pre>
    232     * localeLookupList(Locale("fr", "CA", "xxx"), Locale("en"))
    233     *   = [Locale("fr", "CA", "xxx"), Locale("fr", "CA"), Locale("fr"), Locale("en"]
    234     * </pre>
    235     *
    236     * <p>The result list begins with the most specific locale, then the
    237     * next more general and so on, finishing with the default locale.
    238     * The list will never contain the same locale twice.</p>
    239     *
    240     * @param locale  the locale to start from, null returns empty list
    241     * @param defaultLocale  the default locale to use if no other is found
    242     * @return the unmodifiable list of Locale objects, 0 being locale, not null
    243     */
    244    public static List<Locale> localeLookupList(final Locale locale, final Locale defaultLocale) {
    245        final List<Locale> list = new ArrayList<>(4);
    246        if (locale != null) {
    247            list.add(locale);
    248            if (!locale.getVariant().isEmpty()) {
    249                list.add(new Locale(locale.getLanguage(), locale.getCountry()));
    250            }
    251            if (!locale.getCountry().isEmpty()) {
    252                list.add(new Locale(locale.getLanguage(), StringUtils.EMPTY));
    253            }
    254            if (!list.contains(defaultLocale)) {
    255                list.add(defaultLocale);
    256            }
    257        }
    258        return Collections.unmodifiableList(list);
    259    }
    260
    261    /**
    262     * Tries to parse a Locale from the given String.
    263     * <p>
    264     * See {@link Locale} for the format.
    265     * </p>
    266     *
    267     * @param str the String to parse as a Locale.
    268     * @return a Locale parsed from the given String.
    269     * @throws IllegalArgumentException if the given String cannot be parsed.
    270     * @see Locale
    271     */
    272    private static Locale parseLocale(final String str) {
    273        if (isISO639LanguageCode(str)) {
    274            return new Locale(str);
    275        }
    276        final int limit = 3;
    277        final char separator = str.indexOf(UNDERSCORE) != -1 ? UNDERSCORE : DASH;
    278        final String[] segments = str.split(String.valueOf(separator), 3);
    279        final String language = segments[0];
    280        if (segments.length == 2) {
    281            final String country = segments[1];
    282            if (isISO639LanguageCode(language) && isISO3166CountryCode(country) || isNumericAreaCode(country)) {
    283                return new Locale(language, country);
    284            }
    285        } else if (segments.length == limit) {
    286            final String country = segments[1];
    287            final String variant = segments[2];
    288            if (isISO639LanguageCode(language) &&
    289                    (country.isEmpty() || isISO3166CountryCode(country) || isNumericAreaCode(country)) &&
    290                    !variant.isEmpty()) {
    291                return new Locale(language, country, variant);
    292            }
    293        }
    294        throw new IllegalArgumentException("Invalid locale format: " + str);
    295    }
    296
    297    /**
    298     * Returns the given locale if non-{@code null}, otherwise {@link Locale#getDefault()}.
    299     *
    300     * @param locale a locale or {@code null}.
    301     * @return the given locale if non-{@code null}, otherwise {@link Locale#getDefault()}.
    302     * @since 3.12.0
    303     */
    304    public static Locale toLocale(final Locale locale) {
    305        return locale != null ? locale : Locale.getDefault();
    306    }
    307
    308    /**
    309     * Converts a String to a Locale.
    310     *
    311     * <p>This method takes the string format of a locale and creates the
    312     * locale object from it.</p>
    313     *
    314     * <pre>
    315     *   LocaleUtils.toLocale("")           = new Locale("", "")
    316     *   LocaleUtils.toLocale("en")         = new Locale("en", "")
    317     *   LocaleUtils.toLocale("en_GB")      = new Locale("en", "GB")
    318     *   LocaleUtils.toLocale("en-GB")      = new Locale("en", "GB")
    319     *   LocaleUtils.toLocale("en_001")     = new Locale("en", "001")
    320     *   LocaleUtils.toLocale("en_GB_xxx")  = new Locale("en", "GB", "xxx")   (#)
    321     * </pre>
    322     *
    323     * <p>(#) The behavior of the JDK variant constructor changed between JDK1.3 and JDK1.4.
    324     * In JDK1.3, the constructor upper cases the variant, in JDK1.4, it doesn't.
    325     * Thus, the result from getVariant() may vary depending on your JDK.</p>
    326     *
    327     * <p>This method validates the input strictly.
    328     * The language code must be lowercase.
    329     * The country code must be uppercase.
    330     * The separator must be an underscore or a dash.
    331     * The length must be correct.
    332     * </p>
    333     *
    334     * @param str  the locale String to convert, null returns null
    335     * @return a Locale, null if null input
    336     * @throws IllegalArgumentException if the string is an invalid format
    337     * @see Locale#forLanguageTag(String)
    338     */
    339    public static Locale toLocale(final String str) {
    340        if (str == null) {
    341            // TODO Should this return the default locale?
    342            return null;
    343        }
    344        if (str.isEmpty()) { // LANG-941 - JDK 8 introduced an empty locale where all fields are blank
    345            return new Locale(StringUtils.EMPTY, StringUtils.EMPTY);
    346        }
    347        if (str.contains("#")) { // LANG-879 - Cannot handle Java 7 script & extensions
    348            throw new IllegalArgumentException("Invalid locale format: " + str);
    349        }
    350        final int len = str.length();
    351        if (len < 2) {
    352            throw new IllegalArgumentException("Invalid locale format: " + str);
    353        }
    354        final char ch0 = str.charAt(0);
    355        if (ch0 == UNDERSCORE || ch0 == DASH) {
    356            if (len < 3) {
    357                throw new IllegalArgumentException("Invalid locale format: " + str);
    358            }
    359            final char ch1 = str.charAt(1);
    360            final char ch2 = str.charAt(2);
    361            if (!Character.isUpperCase(ch1) || !Character.isUpperCase(ch2)) {
    362                throw new IllegalArgumentException("Invalid locale format: " + str);
    363            }
    364            if (len == 3) {
    365                return new Locale(StringUtils.EMPTY, str.substring(1, 3));
    366            }
    367            if (len < 5) {
    368                throw new IllegalArgumentException("Invalid locale format: " + str);
    369            }
    370            if (str.charAt(3) != ch0) {
    371                throw new IllegalArgumentException("Invalid locale format: " + str);
    372            }
    373            return new Locale(StringUtils.EMPTY, str.substring(1, 3), str.substring(4));
    374        }
    375
    376        return parseLocale(str);
    377    }
    378
    379    /**
    380     * {@link LocaleUtils} instances should NOT be constructed in standard programming.
    381     * Instead, the class should be used as {@code LocaleUtils.toLocale("en_GB");}.
    382     *
    383     * <p>This constructor is public to permit tools that require a JavaBean instance
    384     * to operate.</p>
    385     *
    386     * @deprecated TODO Make private in 4.0.
    387     */
    388    @Deprecated
    389    public LocaleUtils() {
    390        // empty
    391    }
    392
    393}