// Copyright 2006, 2008 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package org.apache.tapestry.internal.services;
import org.apache.tapestry.TapestryConstants;
import org.apache.tapestry.ioc.Resource;
import org.apache.tapestry.ioc.internal.util.ClasspathResource;
import org.apache.tapestry.services.ClasspathAssetAliasManager;
import org.apache.tapestry.services.Dispatcher;
import org.apache.tapestry.services.Request;
import org.apache.tapestry.services.Response;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.net.URL;
/**
* Recognizes requests where the path begins with "/asset/" and delivers the content therein as a bytestream. Also
* handles requests that are simply polling for a change to the file.
*
* @see ResourceStreamer
* @see ClasspathAssetAliasManager
* @see ResourceCache
*/
public class AssetDispatcher implements Dispatcher
{
private final ResourceStreamer _streamer;
private final ClasspathAssetAliasManager _aliasManager;
private final ResourceCache _resourceCache;
static final String IF_MODIFIED_SINCE_HEADER = "If-Modified-Since";
public AssetDispatcher(ResourceStreamer streamer, ClasspathAssetAliasManager aliasManager,
ResourceCache resourceCache)
{
_streamer = streamer;
_aliasManager = aliasManager;
_resourceCache = resourceCache;
}
public boolean dispatch(Request request, Response response) throws IOException
{
String path = request.getPath();
// Remember that the request path does not include the context path, so we can simply start
// looking for the asset path prefix right off the bat.
if (!path.startsWith(TapestryConstants.ASSET_PATH_PREFIX)) return false;
// ClassLoaders like their paths to start with a leading slash.
String resourcePath = _aliasManager.toResourcePath(path);
Resource resource = findResourceAndValidateDigest(response, resourcePath);
if (resource == null) return true;
URL url = resource.toURL();
if (url == null)
{
response.sendError(HttpServletResponse.SC_NOT_FOUND, ServicesMessages
.assetDoesNotExist(resource));
return true;
}
long ifModifiedSince = 0;
try
{
ifModifiedSince = request.getDateHeader(IF_MODIFIED_SINCE_HEADER);
}
catch (IllegalArgumentException ex)
{
// Simulate the header being missing if it is poorly formatted.
ifModifiedSince = -1;
}
if (ifModifiedSince > 0)
{
long modified = _resourceCache.getTimeModified(resource);
if (ifModifiedSince >= modified)
{
response.sendError(HttpServletResponse.SC_NOT_MODIFIED, "");
return true;
}
}
_streamer.streamResource(resource);
return true;
}
/**
* @param response used to send errors back to the client
* @param resourcePath the path to the requested resource, from the request
* @return the resource for the path, with the digest stripped out of the URL, or null if the digest is invalid (and
* an error has been sent back to the client)
* @throws IOException
*/
private Resource findResourceAndValidateDigest(Response response, String resourcePath) throws IOException
{
Resource resource = new ClasspathResource(resourcePath);
if (!_resourceCache.requiresDigest(resource)) return resource;
String file = resource.getFile();
// Somehow this code got real ugly, but it's all about preventing NPEs when a resource
// that should have a digest doesn't.
boolean valid = false;
Resource result = resource;
int lastdotx = file.lastIndexOf('.');
if (lastdotx > 0)
{
int prevdotx = file.lastIndexOf('.', lastdotx - 1);
if (prevdotx > 0)
{
String requestDigest = file.substring(prevdotx + 1, lastdotx);
// Strip the digest out of the file name.
String realFile = file.substring(0, prevdotx) + file.substring(lastdotx);
result = resource.forFile(realFile);
String actualDigest = _resourceCache.getDigest(result);
valid = requestDigest.equals(actualDigest);
}
}
if (!valid)
{
response.sendError(HttpServletResponse.SC_FORBIDDEN, ServicesMessages
.wrongAssetDigest(result));
result = null;
}
return result;
}
}