RequestUserAgent.java revision 069490a5ca2fd1988d29daf45d892f47ad665115 
1/*
2 * $HeadURL: http://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk/module-main/src/main/java/org/apache/http/protocol/RequestUserAgent.java $
3 * $Revision: 496070 $
4 * $Date: 2007-01-14 04:18:34 -0800 (Sun, 14 Jan 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.HttpRequest;
38import org.apache.http.HttpRequestInterceptor;
39import org.apache.http.params.HttpProtocolParams;
40
41/**
42 * A request interceptor that adds a User-Agent header.
43 *
44 * @author <a href="mailto:oleg at ural.ru">Oleg Kalnichevski</a>
45 *
46 * @version $Revision: 496070 $
47 *
48 * @since 4.0
49 */
50public class RequestUserAgent implements HttpRequestInterceptor {
51
52    public RequestUserAgent() {
53        super();
54    }
55
56    public void process(final HttpRequest request, final HttpContext context)
57        throws HttpException, IOException {
58        if (request == null) {
59            throw new IllegalArgumentException("HTTP request may not be null");
60        }
61        if (!request.containsHeader(HTTP.USER_AGENT)) {
62            String useragent = HttpProtocolParams.getUserAgent(request.getParams());
63            if (useragent != null) {
64                request.addHeader(HTTP.USER_AGENT, useragent);
65            }
66        }
67    }
68
69}
70