1 /*
2 * Copyright 2010 University Corporation for Advanced Internet Development, Inc.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 package edu.internet2.middleware.shibboleth.idp.util;
18
19 import java.io.IOException;
20
21 import javax.servlet.Filter;
22 import javax.servlet.FilterChain;
23 import javax.servlet.FilterConfig;
24 import javax.servlet.ServletException;
25 import javax.servlet.ServletRequest;
26 import javax.servlet.ServletResponse;
27 import javax.servlet.http.HttpServletResponse;
28
29 /**
30 * An HTTP filter that adds the following headers/values to the {@link HttpServletResponse} and thus, hopefully,
31 * prevents caching of the response on all browser.
32 * <ul>
33 * <li>Expires: 0</li>
34 * <li>Cache-Control: no-cache, no-store, must-revalidate, max-age=0
35 * <li>
36 * <li>Pragma: no-cache</li>
37 * </ul>
38 */
39 public class NoCacheFilter implements Filter {
40
41 /** {@inheritDoc} */
42 public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException,
43 ServletException {
44 HttpServletResponse httpResponse = (HttpServletResponse) response;
45
46 httpResponse.setHeader("Expires", "0");
47 httpResponse.setHeader("Cache-Control", "no-cache, no-store, must-revalidate, max-age=0");
48 httpResponse.setHeader("Pragma", "no-cache");
49 chain.doFilter(request, response);
50 }
51
52 /** {@inheritDoc} */
53 public void init(FilterConfig filterConfig) throws ServletException {
54 // nothing to do here
55 }
56
57 /** {@inheritDoc} */
58 public void destroy() {
59 // nothing to do here
60 }
61 }