com.google.gerrit.httpd.GwtCacheControlFilter Maven / Gradle / Ivy
// Copyright (C) 2008 The Android Open Source Project
//
// 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 com.google.gerrit.httpd;
import com.google.gerrit.util.http.CacheHeaders;
import com.google.inject.Singleton;
import java.io.IOException;
import java.util.concurrent.TimeUnit;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Forces GWT resources to cache for a very long time.
*
* GWT compiled JavaScript and ImageBundles can be cached indefinitely by a browser and/or an
* edge proxy, as they never contain user-specific data and are named by a unique checksum. If their
* content is ever modified then the URL changes, so user agents would request a different resource.
* We force these resources to have very long expiration times.
*
*
To use, add the following block to your {@code web.xml}:
*
*
* <filter>
* <filter-name>CacheControl</filter-name>
* <filter-class>com.google.gwtexpui.server.CacheControlFilter</filter-class>
* </filter>
* <filter-mapping>
* <filter-name>CacheControl</filter-name>
* <url-pattern>/*</url-pattern>
* </filter-mapping>
*
*/
@Singleton
class GwtCacheControlFilter implements Filter {
@Override
public void init(FilterConfig config) {}
@Override
public void destroy() {}
@Override
public void doFilter(final ServletRequest sreq, ServletResponse srsp, FilterChain chain)
throws IOException, ServletException {
final HttpServletRequest req = (HttpServletRequest) sreq;
final HttpServletResponse rsp = (HttpServletResponse) srsp;
final String pathInfo = pathInfo(req);
if (cacheForever(pathInfo, req)) {
CacheHeaders.setCacheable(req, rsp, 365, TimeUnit.DAYS);
} else if (nocache(pathInfo)) {
CacheHeaders.setNotCacheable(rsp);
}
chain.doFilter(req, rsp);
}
private static boolean cacheForever(String pathInfo, HttpServletRequest req) {
if (pathInfo.endsWith(".cache.html")
|| pathInfo.endsWith(".cache.gif")
|| pathInfo.endsWith(".cache.png")
|| pathInfo.endsWith(".cache.css")
|| pathInfo.endsWith(".cache.jar")
|| pathInfo.endsWith(".cache.swf")
|| pathInfo.endsWith(".cache.txt")
|| pathInfo.endsWith(".cache.js")) {
return true;
} else if (pathInfo.endsWith(".nocache.js")) {
final String v = req.getParameter("content");
return v != null && v.length() > 20;
}
return false;
}
private static boolean nocache(String pathInfo) {
if (pathInfo.endsWith(".nocache.js")) {
return true;
}
return false;
}
private static String pathInfo(HttpServletRequest req) {
final String uri = req.getRequestURI();
final String ctx = req.getContextPath();
return uri.startsWith(ctx) ? uri.substring(ctx.length()) : uri;
}
}