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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.HttpStatus;
36  import org.apache.http.annotation.ThreadSafe;
37  
38  /**
39   * ResponseDate is responsible for adding <code>Date<c/ode> header to the
40   * outgoing responses. This interceptor is recommended for server side protocol
41   * processors.
42   *
43   * @since 4.0
44   */
45  @ThreadSafe
46  public class ResponseDate implements HttpResponseInterceptor {
47  
48      private static final HttpDateGenerator DATE_GENERATOR = new HttpDateGenerator();
49  
50      public ResponseDate() {
51          super();
52      }
53  
54      public void process(final HttpResponse response, final HttpContext context)
55              throws HttpException, IOException {
56          if (response == null) {
57              throw new IllegalArgumentException
58                  ("HTTP response may not be null.");
59          }
60          int status = response.getStatusLine().getStatusCode();
61          if ((status >= HttpStatus.SC_OK) &&
62              !response.containsHeader(HTTP.DATE_HEADER)) {
63              String httpdate = DATE_GENERATOR.getCurrentDate();
64              response.setHeader(HTTP.DATE_HEADER, httpdate);
65          }
66      }
67  
68  }