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1   // ========================================================================
2   // Copyright (c) 2004-2009 Mort Bay Consulting Pty. Ltd.
3   // ------------------------------------------------------------------------
4   // All rights reserved. This program and the accompanying materials
5   // are made available under the terms of the Eclipse Public License v1.0
6   // and Apache License v2.0 which accompanies this distribution.
7   // The Eclipse Public License is available at 
8   // http://www.eclipse.org/legal/epl-v10.html
9   // The Apache License v2.0 is available at
10  // http://www.opensource.org/licenses/apache2.0.php
11  // You may elect to redistribute this code under either of these licenses. 
12  // ========================================================================
13  
14  package org.eclipse.jetty.rewrite.handler;
15  
16  import java.io.IOException;
17  
18  import javax.servlet.http.HttpServletRequest;
19  import javax.servlet.http.HttpServletResponse;
20  
21  /**
22   * Abstract rule that matches against request headers.
23   */
24  
25  public abstract class HeaderRule extends Rule
26  {
27      private String _header;
28      private String _headerValue;
29  
30      /* ------------------------------------------------------------ */
31      public String getHeader()
32      {
33          return _header;
34      }
35  
36      /* ------------------------------------------------------------ */
37      /**
38       * @param header
39       *                the header name to check for
40       */
41      public void setHeader(String header)
42      {
43          _header = header;
44      }
45  
46      /* ------------------------------------------------------------ */
47      public String getHeaderValue()
48      {
49          return _headerValue;
50      }
51  
52      /* ------------------------------------------------------------ */
53      /**
54       * @param headerValue
55       *                the header value to match against. If null, then the
56       *                presence of the header is enough to match
57       */
58      public void setHeaderValue(String headerValue)
59      {
60          _headerValue = headerValue;
61      }
62  
63      /* ------------------------------------------------------------ */
64      @Override
65      public String matchAndApply(String target, HttpServletRequest request,
66              HttpServletResponse response) throws IOException
67      {
68          String requestHeaderValue = request.getHeader(_header);
69          
70          if (requestHeaderValue != null)
71              if (_headerValue == null || _headerValue.equals(requestHeaderValue))
72                  apply(target, requestHeaderValue, request, response);
73          
74          return null;
75      }
76  
77      /* ------------------------------------------------------------ */
78      /**
79       * Apply the rule to the request
80       * 
81       * @param target
82       *                field to attempt match
83       * @param value 
84       *                header value found
85       * @param request
86       *                request object
87       * @param response
88       *                response object
89       * @return The target (possible updated)
90       * @throws IOException
91       *                 exceptions dealing with operating on request or response
92       *                 objects
93       */
94      protected abstract String apply(String target, String value, HttpServletRequest request, HttpServletResponse response) throws IOException;
95  
96      /* ------------------------------------------------------------ */
97      public String toString()
98      {
99          return super.toString() + "[" + _header + ":" + _headerValue + "]";
100     }
101 
102 }