Source code
Description: source: package: org.apache.commons.lang3, class: LocaleUtils

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