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.ThreadingBehavior;
36 import org.apache.http.annotation.Contract;
37 import org.apache.http.params.CoreProtocolPNames;
38 import org.apache.http.params.HttpParams;
39 import org.apache.http.util.Args;
40
41 /**
42 * RequestUserAgent is responsible for adding {@code User-Agent} header.
43 * This interceptor is recommended for client side protocol processors.
44 *
45 * @since 4.0
46 */
47 @SuppressWarnings("deprecation")
48 @Contract(threading = ThreadingBehavior.IMMUTABLE)
49 public class RequestUserAgent implements HttpRequestInterceptor {
50
51 private final String userAgent;
52
53 public RequestUserAgent(final String userAgent) {
54 super();
55 this.userAgent = userAgent;
56 }
57
58 public RequestUserAgent() {
59 this(null);
60 }
61
62 @Override
63 public void process(final HttpRequest request, final HttpContext context)
64 throws HttpException, IOException {
65 Args.notNull(request, "HTTP request");
66 if (!request.containsHeader(HTTP.USER_AGENT)) {
67 String s = null;
68 final HttpParams params = request.getParams();
69 if (params != null) {
70 s = (String) params.getParameter(CoreProtocolPNames.USER_AGENT);
71 }
72 if (s == null) {
73 s = this.userAgent;
74 }
75 if (s != null) {
76 request.addHeader(HTTP.USER_AGENT, s);
77 }
78 }
79 }
80
81 }