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