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