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.HttpEntity;
33 import org.apache.http.HttpEntityEnclosingRequest;
34 import org.apache.http.HttpException;
35 import org.apache.http.HttpRequest;
36 import org.apache.http.HttpRequestInterceptor;
37 import org.apache.http.HttpVersion;
38 import org.apache.http.ProtocolVersion;
39 import org.apache.http.annotation.Immutable;
40 import org.apache.http.params.HttpProtocolParams;
41
42 /**
43 * RequestExpectContinue is responsible for enabling the 'expect-continue'
44 * handshake by adding <code>Expect</code> header. This interceptor is
45 * recommended for client side protocol processors.
46 * <p>
47 * The following parameters can be used to customize the behavior of this
48 * class:
49 * <ul>
50 * <li>{@link org.apache.http.params.CoreProtocolPNames#USE_EXPECT_CONTINUE}</li>
51 * </ul>
52 *
53 * @since 4.0
54 */
55 @Immutable
56 public class RequestExpectContinue implements HttpRequestInterceptor {
57
58 public RequestExpectContinue() {
59 super();
60 }
61
62 public void process(final HttpRequest request, final HttpContext context)
63 throws HttpException, IOException {
64 if (request == null) {
65 throw new IllegalArgumentException("HTTP request may not be null");
66 }
67 if (request instanceof HttpEntityEnclosingRequest) {
68 HttpEntity entity = ((HttpEntityEnclosingRequest)request).getEntity();
69 // Do not send the expect header if request body is known to be empty
70 if (entity != null && entity.getContentLength() != 0) {
71 ProtocolVersion ver = request.getRequestLine().getProtocolVersion();
72 if (HttpProtocolParams.useExpectContinue(request.getParams())
73 && !ver.lessEquals(HttpVersion.HTTP_1_0)) {
74 request.addHeader(HTTP.EXPECT_DIRECTIVE, HTTP.EXPECT_CONTINUE);
75 }
76 }
77 }
78 }
79
80 }