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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.ThreadingBehavior;
40  import org.apache.http.annotation.Contract;
41  import org.apache.http.params.CoreProtocolPNames;
42  import org.apache.http.util.Args;
43  
44  /**
45   * RequestExpectContinue is responsible for enabling the 'expect-continue'
46   * handshake by adding {@code Expect} header. This interceptor is
47   * recommended for client side protocol processors.
48   *
49   * @since 4.0
50   */
51  @Contract(threading = ThreadingBehavior.IMMUTABLE)
52  @SuppressWarnings("deprecation")
53  public class RequestExpectContinue implements HttpRequestInterceptor {
54  
55      private final boolean activeByDefault;
56  
57      /**
58       * @deprecated (4.3) use {@link org.apache.http.protocol.RequestExpectContinue#RequestExpectContinue(boolean)}
59       */
60      @Deprecated
61      public RequestExpectContinue() {
62          this(false);
63      }
64  
65      /**
66       * @since 4.3
67       */
68      public RequestExpectContinue(final boolean activeByDefault) {
69          super();
70          this.activeByDefault = activeByDefault;
71      }
72  
73      @Override
74      public void process(final HttpRequest request, final HttpContext context)
75              throws HttpException, IOException {
76          Args.notNull(request, "HTTP request");
77  
78          if (!request.containsHeader(HTTP.EXPECT_DIRECTIVE)) {
79              if (request instanceof HttpEntityEnclosingRequest) {
80                  final ProtocolVersion ver = request.getRequestLine().getProtocolVersion();
81                  final HttpEntity entity = ((HttpEntityEnclosingRequest)request).getEntity();
82                  // Do not send the expect header if request body is known to be empty
83                  if (entity != null
84                          && entity.getContentLength() != 0 && !ver.lessEquals(HttpVersion.HTTP_1_0)) {
85                      final boolean active = request.getParams().getBooleanParameter(
86                              CoreProtocolPNames.USE_EXPECT_CONTINUE, this.activeByDefault);
87                      if (active) {
88                          request.addHeader(HTTP.EXPECT_DIRECTIVE, HTTP.EXPECT_CONTINUE);
89                      }
90                  }
91              }
92          }
93      }
94  
95  }