// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// to you 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 com.cloud.servlet;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.io.IOUtils;
import org.apache.commons.lang.StringUtils;
/**
* Serves static resources with support for gzip compression and content
* caching.
*/
public class StaticResourceServlet extends HttpServlet {
private static final long serialVersionUID = -8833228931973461812L;
private File getRequestedFile(final HttpServletRequest req) {
return new File(getServletContext().getRealPath(req.getServletPath()));
}
@Override
protected void doGet(final HttpServletRequest req,
final HttpServletResponse resp) throws ServletException,
IOException {
final File requestedFile = getRequestedFile(req);
if (!requestedFile.exists() || !requestedFile.isFile()) {
resp.setStatus(HttpServletResponse.SC_NOT_FOUND);
return;
}
final String etag = getEtag(requestedFile);
if (etag.equals(req.getHeader("If-None-Match"))) {
resp.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
return;
}
// have to send data, either compressed or the original
final File compressedStatic = getCompressedVersion(requestedFile);
InputStream fileContent = null;
try {
resp.setContentType(getContentType(requestedFile.getName()));
resp.setHeader("ETag", etag);
resp.setStatus(HttpServletResponse.SC_OK);
if (isClientCompressionSupported(req) && compressedStatic.exists()) {
// gzip compressed
resp.setHeader("Content-Encoding", "gzip");
resp.setContentLength((int) compressedStatic.length());
fileContent = new FileInputStream(compressedStatic);
} else {
// uncompressed
resp.setContentLength((int) requestedFile.length());
fileContent = new FileInputStream(requestedFile);
}
IOUtils.copy(fileContent, resp.getOutputStream());
} finally {
IOUtils.closeQuietly(fileContent);
}
}
@SuppressWarnings("serial")
static final Map<String, String> contentTypes = Collections
.unmodifiableMap(new HashMap<String, String>() {
{
put("css", "text/css");
put("svg", "image/svg+xml");
put("js", "application/javascript");
put("htm", "text/html");
put("html", "text/html");
put("txt", "text/plain");
put("xml", "text/xml");
}
});
static String getContentType(final String fileName) {
return contentTypes.get(StringUtils.lowerCase(StringUtils
.substringAfterLast(fileName, ".")));
}
static File getCompressedVersion(final File requestedFile) {
return new File(requestedFile.getAbsolutePath() + ".gz");
}
static boolean isClientCompressionSupported(final HttpServletRequest req) {
return StringUtils.contains(req.getHeader("Accept-Encoding"), "gzip");
}
static String getEtag(final File resource) {
return "W/\"" + resource.length() + "-" + resource.lastModified();
}
}