102 lines
3.5 KiB
Java
102 lines
3.5 KiB
Java
// Copyright (C) 2008 The Android Open Source Project
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package com.google.gwtexpui.server;
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import java.io.IOException;
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import java.util.concurrent.TimeUnit;
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import javax.servlet.Filter;
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import javax.servlet.FilterChain;
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import javax.servlet.FilterConfig;
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import javax.servlet.ServletException;
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import javax.servlet.ServletRequest;
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import javax.servlet.ServletResponse;
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import javax.servlet.http.HttpServletRequest;
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import javax.servlet.http.HttpServletResponse;
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/**
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* Forces GWT resources to cache for a very long time.
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*
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* <p>GWT compiled JavaScript and ImageBundles can be cached indefinitely by a browser and/or an
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* edge proxy, as they never contain user-specific data and are named by a unique checksum. If their
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* content is ever modified then the URL changes, so user agents would request a different resource.
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* We force these resources to have very long expiration times.
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*
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* <p>To use, add the following block to your {@code web.xml}:
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*
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* <pre>
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* <filter>
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* <filter-name>CacheControl</filter-name>
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* <filter-class>com.google.gwtexpui.server.CacheControlFilter</filter-class>
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* </filter>
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* <filter-mapping>
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* <filter-name>CacheControl</filter-name>
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* <url-pattern>/*</url-pattern>
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* </filter-mapping>
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* </pre>
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*/
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public class CacheControlFilter implements Filter {
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@Override
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public void init(FilterConfig config) {}
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@Override
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public void destroy() {}
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@Override
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public void doFilter(final ServletRequest sreq, ServletResponse srsp, FilterChain chain)
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throws IOException, ServletException {
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final HttpServletRequest req = (HttpServletRequest) sreq;
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final HttpServletResponse rsp = (HttpServletResponse) srsp;
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final String pathInfo = pathInfo(req);
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if (cacheForever(pathInfo, req)) {
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CacheHeaders.setCacheable(req, rsp, 365, TimeUnit.DAYS);
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} else if (nocache(pathInfo)) {
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CacheHeaders.setNotCacheable(rsp);
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}
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chain.doFilter(req, rsp);
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}
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private static boolean cacheForever(String pathInfo, HttpServletRequest req) {
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if (pathInfo.endsWith(".cache.html")
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|| pathInfo.endsWith(".cache.gif")
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|| pathInfo.endsWith(".cache.png")
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|| pathInfo.endsWith(".cache.css")
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|| pathInfo.endsWith(".cache.jar")
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|| pathInfo.endsWith(".cache.swf")
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|| pathInfo.endsWith(".cache.txt")
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|| pathInfo.endsWith(".cache.js")) {
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return true;
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} else if (pathInfo.endsWith(".nocache.js")) {
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final String v = req.getParameter("content");
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return v != null && v.length() > 20;
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}
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return false;
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}
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private static boolean nocache(String pathInfo) {
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if (pathInfo.endsWith(".nocache.js")) {
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return true;
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}
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return false;
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}
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private static String pathInfo(HttpServletRequest req) {
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final String uri = req.getRequestURI();
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final String ctx = req.getContextPath();
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return uri.startsWith(ctx) ? uri.substring(ctx.length()) : uri;
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}
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}
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