    001// Licensed under the Apache License, Version 2.0 (the "License");
    002// you may not use this file except in compliance with the License.
    003// You may obtain a copy of the License at
    004//
    005//     http://www.apache.org/licenses/LICENSE-2.0
    006//
    007// Unless required by applicable law or agreed to in writing, software
    008// distributed under the License is distributed on an "AS IS" BASIS,
    009// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    010// See the License for the specific language governing permissions and
    011// limitations under the License.
    012
    013package org.apache.tapestry5.internal.util;
    014
    015import java.util.Locale;
    016
    017/**
    018 * Contains code borrowed from <a href="http://commons.apache.org/lang/">commons-lang</a>.
    019 */
    020public class LocaleUtils
    021{
    022    /**
    023     * Converts a String to a Locale.  This method takes the string format of a locale and creates the
    024     * locale object from it.
    025     * <pre>
    026     *   LocaleUtils.toLocale("en")         = new Locale("en", "")
    027     *   LocaleUtils.toLocale("en_GB")      = new Locale("en", "GB")
    028     *   LocaleUtils.toLocale("en_GB_xxx")  = new Locale("en", "GB", "xxx")   (#)
    029     * </pre>
    030     *  (#) The behaviour of the JDK variant constructor changed between JDK1.3 and JDK1.4. In JDK1.3, the
    031     * constructor upper cases the variant, in JDK1.4, it doesn't. Thus, the result from getVariant() may vary depending
    032     * on your JDK.  This method validates the input strictly. The language code must be lowercase. The
    033     * country code must be uppercase. The separator must be an underscore. The length must be correct.
    034     *
    035     * @param input the locale String to convert, null returns null
    036     * @return a Locale, null if null input
    037     * @throws IllegalArgumentException if the string is an invalid format
    038     */
    039    public static Locale toLocale(String input)
    040    {
    041        if (input == null)
    042            return null;
    043
    044        int len = input.length();
    045        if (len != 2 && len != 5 && len < 7)
    046            fail(input);
    047
    048        char ch0 = input.charAt(0);
    049        char ch1 = input.charAt(1);
    050
    051        if (ch0 < 'a' || ch0 > 'z' || ch1 < 'a' || ch1 > 'z')
    052            fail(input);
    053
    054        if (len == 2)
    055            return new Locale(input, "");
    056
    057        if (input.charAt(2) != '_')
    058            fail(input);
    059
    060        char ch3 = input.charAt(3);
    061        if (ch3 == '_')
    062            return new Locale(input.substring(0, 2), "", input.substring(4));
    063
    064        char ch4 = input.charAt(4);
    065        if (ch3 < 'A' || ch3 > 'Z' || ch4 < 'A' || ch4 > 'Z')
    066            fail(input);
    067
    068        if (len == 5)
    069            return new Locale(input.substring(0, 2), input.substring(3, 5));
    070
    071        if (input.charAt(5) != '_')
    072            fail(input);
    073
    074        return new Locale(input.substring(0, 2), input.substring(3, 5), input.substring(6));
    075    }
    076
    077    private static void fail(String input)
    078    {
    079        throw new IllegalArgumentException(String.format("Unable to convert '%s' to a Locale instance.", input));
    080    }
    081
    082}