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.asset;
016    
017    import org.apache.hivemind.ApplicationRuntimeException;
018    import org.apache.hivemind.Location;
019    import org.apache.hivemind.Resource;
020    import org.apache.hivemind.util.Defense;
021    import org.apache.tapestry.IAsset;
022    import org.apache.tapestry.IRequestCycle;
023    import org.apache.tapestry.Tapestry;
024    
025    import java.io.InputStream;
026    import java.net.URL;
027    
028    /**
029     * An asset whose path is relative to the {@link javax.servlet.ServletContext} containing the
030     * application.
031     *
032     * @author Howard Lewis Ship
033     */
034    
035    public class ContextAsset extends AbstractAsset implements IAsset
036    {
037        private String _contextPath;
038    
039        private String _resolvedURL;
040    
041        private IRequestCycle _requestCycle;
042    
043        public ContextAsset(String contextPath, Resource resource, Location location, IRequestCycle cycle)
044        {
045            super(resource, location);
046    
047            Defense.notNull(contextPath, "contextPath");
048    
049            _contextPath = contextPath;
050    
051            _requestCycle = cycle;
052        }
053    
054        /**
055         * Generates a URL for the client to retrieve the asset. The context path is prepended to the
056         * asset path, which means that assets deployed inside web applications will still work (if
057         * things are configured properly).
058         */
059    
060        public String buildURL()
061        {
062            if (_resolvedURL == null)
063                _resolvedURL = _contextPath + getResourceLocation().getPath();
064    
065            return _resolvedURL;
066        }
067    
068        public InputStream getResourceAsStream()
069        {
070            try
071            {
072                URL url = getResourceLocation().getResourceURL();
073    
074                return url.openStream();
075            }
076            catch (Exception ex)
077            {
078                throw new ApplicationRuntimeException(Tapestry.format(
079                  "ContextAsset.resource-missing",
080                  getResourceLocation()), ex);
081            }
082        }
083    }