    001    // Copyright 2008 The Apache Software Foundation
    002    //
    003    // Licensed under the Apache License, Version 2.0 (the "License");
    004    // you may not use this file except in compliance with the License.
    005    // You may obtain a copy of the License at
    006    //
    007    //     http://www.apache.org/licenses/LICENSE-2.0
    008    //
    009    // Unless required by applicable law or agreed to in writing, software
    010    // distributed under the License is distributed on an "AS IS" BASIS,
    011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    012    // See the License for the specific language governing permissions and
    013    // limitations under the License.
    014
    015    package org.apache.tapestry5.internal.util;
    016
    017    import java.util.Locale;
    018
    019    /**
    020     * Contains code borrowed from <a href="http://commons.apache.org/lang/">commons-lang</a>.
    021     */
    022    public class LocaleUtils
    023    {
    024        /**
    025         * <p>Converts a String to a Locale.</p> <p/> <p>This method takes the string format of a locale and creates the
    026         * locale object from it.</p> <p/>
    027         * <pre>
    028         *   LocaleUtils.toLocale("en")         = new Locale("en", "")
    029         *   LocaleUtils.toLocale("en_GB")      = new Locale("en", "GB")
    030         *   LocaleUtils.toLocale("en_GB_xxx")  = new Locale("en", "GB", "xxx")   (#)
    031         * </pre>
    032         * <p/> <p>(#) The behaviour of the JDK variant constructor changed between JDK1.3 and JDK1.4. In JDK1.3, the
    033         * constructor upper cases the variant, in JDK1.4, it doesn't. Thus, the result from getVariant() may vary depending
    034         * on your JDK.</p> <p/> <p>This method validates the input strictly. The language code must be lowercase. The
    035         * country code must be uppercase. The separator must be an underscore. The length must be correct. </p>
    036         *
    037         * @param input the locale String to convert, null returns null
    038         * @return a Locale, null if null input
    039         * @throws IllegalArgumentException if the string is an invalid format
    040         */
    041        public static Locale toLocale(String input)
    042        {
    043            if (input == null)
    044                return null;
    045
    046            int len = input.length();
    047            if (len != 2 && len != 5 && len < 7)
    048                fail(input);
    049
    050            char ch0 = input.charAt(0);
    051            char ch1 = input.charAt(1);
    052
    053            if (ch0 < 'a' || ch0 > 'z' || ch1 < 'a' || ch1 > 'z')
    054                fail(input);
    055
    056            if (len == 2)
    057                return new Locale(input, "");
    058
    059            if (input.charAt(2) != '_')
    060                fail(input);
    061
    062            char ch3 = input.charAt(3);
    063            if (ch3 == '_')
    064                return new Locale(input.substring(0, 2), "", input.substring(4));
    065
    066            char ch4 = input.charAt(4);
    067            if (ch3 < 'A' || ch3 > 'Z' || ch4 < 'A' || ch4 > 'Z')
    068                fail(input);
    069
    070            if (len == 5)
    071                return new Locale(input.substring(0, 2), input.substring(3, 5));
    072
    073            if (input.charAt(5) != '_')
    074                fail(input);
    075
    076            return new Locale(input.substring(0, 2), input.substring(3, 5), input.substring(6));
    077        }
    078
    079        private static void fail(String input)
    080        {
    081            throw new IllegalArgumentException(String.format("Unable to convert '%s' to a Locale instance.", input));
    082        }
    083
    084    }