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.wicket.extensions.util.encoding;
018
019import java.io.IOException;
020import java.io.InputStream;
021
022import javax.servlet.ServletContext;
023
024import org.apache.wicket.Application;
025import org.apache.wicket.Session;
026import org.apache.wicket.WicketRuntimeException;
027import org.apache.wicket.protocol.http.WebApplication;
028import org.apache.wicket.request.cycle.RequestCycle;
029import org.slf4j.Logger;
030import org.slf4j.LoggerFactory;
031
032
033/**
034 * Utility class. Initialize Locale to character encoding mapping based on defaults and optionally a
035 * properties file CharSetMap.CHARSET_RESOURCE to be found in WEB-INF.
036 * 
037 * @author Jonathan Locke
038 * @author Juergen Donnerstag
039 */
040public class CharSetUtil
041{
042        /** Logging */
043        private static final Logger log = LoggerFactory.getLogger(CharSetUtil.class);
044
045        /** Locale to character encoding mapping */
046        private static CharSetMap charSetMap;
047
048        /**
049         * Constructor
050         */
051        public CharSetUtil()
052        {
053        }
054
055        /**
056         * Initialize the mapping table based on defaults and optionally modified by entries from a
057         * properties file to be found in WEB-INF.
058         * 
059         * @param application
060         *            Wicket application object
061         */
062        private synchronized static void initialize(final WebApplication application)
063        {
064                if (charSetMap == null)
065                {
066                        // Get servlet context
067                        final ServletContext context = application.getServletContext();
068
069                        final InputStream inputStream = context.getResourceAsStream("/WEB-INF/" +
070                                CharSetMap.CHARSET_RESOURCE);
071
072                        if (inputStream == null)
073                        {
074                                charSetMap = new CharSetMap();
075                                if (log.isDebugEnabled())
076                                {
077                                        log.debug("File '" + CharSetMap.CHARSET_RESOURCE + "' not found");
078                                }
079                        }
080                        else
081                        {
082                                try
083                                {
084                                        charSetMap = new CharSetMap(inputStream);
085                                }
086                                catch (IOException ex)
087                                {
088                                        throw new WicketRuntimeException("Error while reading CharSetMap", ex);
089                                }
090                        }
091                }
092        }
093
094        /**
095         * Based on the Session's locale determine the associated character encoding.
096         * 
097         * @param cycle
098         * @return Char set to use for response.
099         */
100        public static String getEncoding(final RequestCycle cycle)
101        {
102                if (charSetMap == null)
103                {
104                        initialize((WebApplication)Application.get());
105                }
106
107                return charSetMap.getCharSet(Session.get().getLocale());
108        }
109}