001    // Copyright 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.engine.encoders;
016    
017    import org.apache.tapestry.Tapestry;
018    import org.apache.tapestry.asset.AssetService;
019    import org.apache.tapestry.engine.ServiceEncoder;
020    import org.apache.tapestry.engine.ServiceEncoding;
021    import org.apache.tapestry.services.ServiceConstants;
022    
023    /**
024     * Encoder for the {@link org.apache.tapestry.asset.AssetService} that uses servlet path info
025     * to store the resource digest and the path to the resource.
026     * 
027     * @author Howard M. Lewis Ship
028     * @since 4.0
029     */
030    public class AssetEncoder implements ServiceEncoder
031    {
032        public static final String DIGEST_STATIC = "static";
033        
034        private String _path;
035    
036        public void setPath(String path)
037        {
038            _path = path;
039        }
040    
041        public void encode(ServiceEncoding encoding)
042        {
043            if (!encoding.getParameterValue(ServiceConstants.SERVICE).equals(Tapestry.ASSET_SERVICE))
044                return;
045    
046            String path = encoding.getParameterValue(AssetService.PATH);
047            String digest = encoding.getParameterValue(AssetService.DIGEST);
048    
049            // _path ends with a slash, path starts with one.
050            
051            String fullPath = _path + ((digest != null) ? "/" + digest : "/" + DIGEST_STATIC) + path;
052            
053            encoding.setServletPath(fullPath);
054            encoding.setParameterValue(AssetService.PATH, null);
055            encoding.setParameterValue(AssetService.DIGEST, null);
056            encoding.setParameterValue(ServiceConstants.SERVICE, null);
057        }
058    
059        public void decode(ServiceEncoding encoding)
060        {
061            if (!encoding.getServletPath().equals(_path))
062                return;
063            
064            String pathInfo = encoding.getPathInfo();
065            
066            // The lead character is a slash, so find the next slash (the divider between the
067            // digest and the path).
068            int slashx = pathInfo.indexOf('/', 1);
069            
070            encoding.setParameterValue(ServiceConstants.SERVICE, Tapestry.ASSET_SERVICE);
071            encoding.setParameterValue(AssetService.DIGEST, pathInfo.substring(1, slashx));
072            encoding.setParameterValue(AssetService.PATH, pathInfo.substring(slashx));
073        }
074        
075    }