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.HttpRequest;
34 import org.apache.http.HttpRequestInterceptor;
35 import org.apache.http.annotation.Immutable;
36 import org.apache.http.params.HttpProtocolParams;
37
38 /**
39 * RequestUserAgent is responsible for adding <code>User-Agent</code> header.
40 * This interceptor is recommended for client side protocol processors.
41 * <p>
42 * The following parameters can be used to customize the behavior of this
43 * class:
44 * <ul>
45 * <li>{@link org.apache.http.params.CoreProtocolPNames#USER_AGENT}</li>
46 * </ul>
47 *
48 * @since 4.0
49 */
50 @Immutable
51 public class RequestUserAgent implements HttpRequestInterceptor {
52
53 public RequestUserAgent() {
54 super();
55 }
56
57 public void process(final HttpRequest request, final HttpContext context)
58 throws HttpException, IOException {
59 if (request == null) {
60 throw new IllegalArgumentException("HTTP request may not be null");
61 }
62 if (!request.containsHeader(HTTP.USER_AGENT)) {
63 String useragent = HttpProtocolParams.getUserAgent(request.getParams());
64 if (useragent != null) {
65 request.addHeader(HTTP.USER_AGENT, useragent);
66 }
67 }
68 }
69
70 }