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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.common.log;
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  
28  import org.slf4j.MDC;
29  
30  /**
31   * A Servlet filter which clears all the MDC state that has been accumulated during the processing of a request. It
32   * should be installed as near as possible to the beginning of the effective filter chain - and in particular prior to
33   * any filters which make use of MDC in their own logging - so that this filter will be last when the request stack
34   * unwinds.
35   */
36  public class SLF4JMDCCleanupFilter implements Filter {
37  
38      /** {@inheritDoc} */
39      public void destroy() {
40      }
41  
42      /** {@inheritDoc} */
43      public void init(FilterConfig filterConfig) throws ServletException {
44      }
45  
46      /** {@inheritDoc} */
47      public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException,
48              ServletException {
49  
50          try {
51              chain.doFilter(request, response);
52          } finally {
53              MDC.clear();
54          }
55  
56      }
57  
58  }