    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
    015package org.apache.tapestry5.internal.util;
    016
    017import java.util.Locale;
    018
    019/**
    020 * Contains code borrowed from <a href="http://commons.apache.org/lang/">commons-lang</a>.
    021 */
    022public 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}