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 }