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1   /*
2    * Licensed to the University Corporation for Advanced Internet Development, 
3    * Inc. (UCAID) under one or more contributor license agreements.  See the 
4    * NOTICE file distributed with this work for additional information regarding
5    * copyright ownership. The UCAID licenses this file to You under the Apache 
6    * License, Version 2.0 (the "License"); you may not use this file except in 
7    * compliance with the License.  You may obtain a copy of the License at
8    *
9    *    http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  
18  package edu.internet2.middleware.shibboleth.idp.util;
19  
20  import java.io.IOException;
21  
22  import javax.servlet.Filter;
23  import javax.servlet.FilterChain;
24  import javax.servlet.FilterConfig;
25  import javax.servlet.ServletException;
26  import javax.servlet.ServletRequest;
27  import javax.servlet.ServletResponse;
28  import javax.servlet.http.HttpServletResponse;
29  
30  /**
31   * An HTTP filter that adds the following headers/values to the {@link HttpServletResponse} and thus, hopefully,
32   * prevents caching of the response on all browser.
33   * <ul>
34   * <li>Expires: 0</li>
35   * <li>Cache-Control: no-cache, no-store, must-revalidate, max-age=0
36   * <li>
37   * <li>Pragma: no-cache</li>
38   * </ul>
39   */
40  public class NoCacheFilter implements Filter {
41  
42      /** {@inheritDoc} */
43      public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException,
44              ServletException {
45          HttpServletResponse httpResponse = (HttpServletResponse) response;
46  
47          httpResponse.setHeader("Expires", "0");
48          httpResponse.setHeader("Cache-Control", "no-cache, no-store, must-revalidate, max-age=0");
49          httpResponse.setHeader("Pragma", "no-cache");
50          chain.doFilter(request, response);
51      }
52  
53      /** {@inheritDoc} */
54      public void init(FilterConfig filterConfig) throws ServletException {
55          // nothing to do here
56      }
57  
58      /** {@inheritDoc} */
59      public void destroy() {
60          // nothing to do here
61      }
62  }