1/*
2 * $HeadURL: http://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk/module-main/src/main/java/org/apache/http/protocol/ResponseDate.java $
3 * $Revision: 555989 $
4 * $Date: 2007-07-13 06:33:39 -0700 (Fri, 13 Jul 2007) $
5 *
6 * ====================================================================
7 * Licensed to the Apache Software Foundation (ASF) under one
8 * or more contributor license agreements.  See the NOTICE file
9 * distributed with this work for additional information
10 * regarding copyright ownership.  The ASF licenses this file
11 * to you under the Apache License, Version 2.0 (the
12 * "License"); you may not use this file except in compliance
13 * with the License.  You may obtain a copy of the License at
14 *
15 *   http://www.apache.org/licenses/LICENSE-2.0
16 *
17 * Unless required by applicable law or agreed to in writing,
18 * software distributed under the License is distributed on an
19 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
20 * KIND, either express or implied.  See the License for the
21 * specific language governing permissions and limitations
22 * under the License.
23 * ====================================================================
24 *
25 * This software consists of voluntary contributions made by many
26 * individuals on behalf of the Apache Software Foundation.  For more
27 * information on the Apache Software Foundation, please see
28 * <http://www.apache.org/>.
29 *
30 */
31
32package org.apache.http.protocol;
33
34import java.io.IOException;
35
36import org.apache.http.HttpException;
37import org.apache.http.HttpResponse;
38import org.apache.http.HttpResponseInterceptor;
39import org.apache.http.HttpStatus;
40
41/**
42 * A response interceptor that adds a Date header.
43 * For use on the server side.
44 *
45 * @author <a href="mailto:oleg at ural.ru">Oleg Kalnichevski</a>
46 *
47 * @version $Revision: 555989 $
48 *
49 * @since 4.0
50 */
51public class ResponseDate implements HttpResponseInterceptor {
52
53    private static final HttpDateGenerator DATE_GENERATOR = new HttpDateGenerator();
54
55    public ResponseDate() {
56        super();
57    }
58
59    public void process(final HttpResponse response, final HttpContext context)
60            throws HttpException, IOException {
61        if (response == null) {
62            throw new IllegalArgumentException
63                ("HTTP response may not be null.");
64        }
65        int status = response.getStatusLine().getStatusCode();
66        if ((status >= HttpStatus.SC_OK) &&
67            !response.containsHeader(HTTP.DATE_HEADER)) {
68            String httpdate = DATE_GENERATOR.getCurrentDate();
69            response.setHeader(HTTP.DATE_HEADER, httpdate);
70        }
71    }
72
73}
74