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
015package org.apache.tapestry.asset;
016
017import java.io.InputStream;
018import java.net.URL;
019
020import org.apache.hivemind.ApplicationRuntimeException;
021import org.apache.hivemind.Location;
022import org.apache.hivemind.Resource;
023import org.apache.hivemind.util.Defense;
024import org.apache.tapestry.IAsset;
025import org.apache.tapestry.IRequestCycle;
026import org.apache.tapestry.Tapestry;
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
035public 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 _requestCycle.encodeURL(_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}