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1   /**
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  package org.apache.hadoop.hbase.http;
19  
20  import javax.servlet.Filter;
21  import javax.servlet.FilterChain;
22  import javax.servlet.FilterConfig;
23  import javax.servlet.ServletException;
24  import javax.servlet.ServletRequest;
25  import javax.servlet.ServletResponse;
26  import javax.servlet.http.HttpServletResponse;
27  import java.io.IOException;
28  
29  import org.apache.hadoop.hbase.classification.InterfaceAudience;
30  import org.apache.hadoop.hbase.HBaseInterfaceAudience;
31  
32  @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.CONFIG)
33  public class NoCacheFilter implements Filter {
34  
35    @Override
36    public void init(FilterConfig filterConfig) throws ServletException {
37    }
38  
39    @Override
40    public void doFilter(ServletRequest req, ServletResponse res,
41                         FilterChain chain)
42      throws IOException, ServletException {
43      HttpServletResponse httpRes = (HttpServletResponse) res;
44      httpRes.setHeader("Cache-Control", "no-cache");
45      long now = System.currentTimeMillis();
46      httpRes.addDateHeader("Expires", now);
47      httpRes.addDateHeader("Date", now);
48      httpRes.addHeader("Pragma", "no-cache");
49      chain.doFilter(req, res);
50    }
51  
52    @Override
53    public void destroy() {
54    }
55  
56  }