| // 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.gwtexpui.server; |
| |
| 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. |
| * |
| * <p>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. |
| * |
| * <p>To use, add the following block to your {@code web.xml}: |
| * |
| * <pre> |
| * <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> |
| * </pre> |
| */ |
| public class CacheControlFilter implements Filter { |
| @Override |
| public void init(final FilterConfig config) {} |
| |
| @Override |
| public void destroy() {} |
| |
| @Override |
| public void doFilter( |
| final ServletRequest sreq, final ServletResponse srsp, final 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(final String pathInfo, final 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(final String pathInfo) { |
| if (pathInfo.endsWith(".nocache.js")) { |
| return true; |
| } |
| return false; |
| } |
| |
| private static String pathInfo(final HttpServletRequest req) { |
| final String uri = req.getRequestURI(); |
| final String ctx = req.getContextPath(); |
| return uri.startsWith(ctx) ? uri.substring(ctx.length()) : uri; |
| } |
| } |