001    // Copyright 2004, 2005 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.tapestry.web;
016    
017    import org.apache.hivemind.util.Defense;
018    import org.apache.hivemind.util.LocalizedNameGenerator;
019    import org.apache.hivemind.util.LocalizedResource;
020    
021    import java.util.Locale;
022    
023    /**
024     * Finds localized resources within a {@link org.apache.tapestry.web.WebContext}..
025     * 
026     * @author Howard Lewis Ship
027     * @since 4.0
028     */
029    
030    public class LocalizedWebContextResourceFinder
031    {
032    
033        private WebContext _context;
034    
035        public LocalizedWebContextResourceFinder(WebContext context)
036        {
037            Defense.notNull(context, "context");
038    
039            _context = context;
040        }
041    
042        /**
043         * Resolves the resource, returning a path representing the closest match
044         * (with respect to the provided locale). Returns null if no match.
045         * <p>
046         * The provided path is split into a base path and a suffix (at the last
047         * period character). The locale will provide different suffixes to the base
048         * path and the first match is returned.
049         */
050    
051        public LocalizedResource resolve(String contextPath, Locale locale)
052        {
053            int dotx = contextPath.lastIndexOf('.');
054            String basePath;
055            String suffix;
056            if (dotx >= 0)
057            {
058                basePath = contextPath.substring(0, dotx);
059                suffix = contextPath.substring(dotx);
060            }
061            else
062            {
063                // Resource without extension
064                basePath = contextPath;
065                suffix = "";
066            }
067    
068            LocalizedNameGenerator generator = new LocalizedNameGenerator(basePath,
069                    locale, suffix);
070    
071            while(generator.more())
072            {
073                String candidatePath = generator.next();
074    
075                if (isExistingResource(candidatePath))
076                    return new LocalizedResource(candidatePath, generator.getCurrentLocale());
077            }
078    
079            return null;
080        }
081    
082        private boolean isExistingResource(String path)
083        {
084            return _context.getResource(path) != null;
085        }
086    }