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1   /*
2    * ====================================================================
3    * Licensed to the Apache Software Foundation (ASF) under one
4    * or more contributor license agreements.  See the NOTICE file
5    * distributed with this work for additional information
6    * regarding copyright ownership.  The ASF licenses this file
7    * to you under the Apache License, Version 2.0 (the
8    * "License"); you may not use this file except in compliance
9    * with the License.  You may obtain a copy of the License at
10   *
11   *   http://www.apache.org/licenses/LICENSE-2.0
12   *
13   * Unless required by applicable law or agreed to in writing,
14   * software distributed under the License is distributed on an
15   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16   * KIND, either express or implied.  See the License for the
17   * specific language governing permissions and limitations
18   * under the License.
19   * ====================================================================
20   *
21   * This software consists of voluntary contributions made by many
22   * individuals on behalf of the Apache Software Foundation.  For more
23   * information on the Apache Software Foundation, please see
24   * <http://www.apache.org/>.
25   *
26   */
27  
28  package org.apache.http.protocol;
29  
30  import java.io.IOException;
31  
32  import org.apache.http.HttpException;
33  import org.apache.http.HttpResponse;
34  import org.apache.http.HttpResponseInterceptor;
35  import org.apache.http.annotation.ThreadingBehavior;
36  import org.apache.http.annotation.Contract;
37  import org.apache.http.util.Args;
38  
39  /**
40   * ResponseServer is responsible for adding {@code Server} header. This
41   * interceptor is recommended for server side protocol processors.
42   *
43   * @since 4.0
44   */
45  @Contract(threading = ThreadingBehavior.IMMUTABLE)
46  public class ResponseServer implements HttpResponseInterceptor {
47  
48      private final String originServer;
49  
50      /**
51       * @since 4.3
52       */
53      public ResponseServer(final String originServer) {
54          super();
55          this.originServer = originServer;
56      }
57  
58      public ResponseServer() {
59          this(null);
60      }
61  
62      @Override
63      public void process(final HttpResponse response, final HttpContext context)
64              throws HttpException, IOException {
65          Args.notNull(response, "HTTP response");
66          if (!response.containsHeader(HTTP.SERVER_HEADER)) {
67              if (this.originServer != null) {
68                  response.addHeader(HTTP.SERVER_HEADER, this.originServer);
69              }
70          }
71      }
72  
73  }