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      1 /*
      2  * $HeadURL: http://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk/module-main/src/main/java/org/apache/http/protocol/RequestExpectContinue.java $
      3  * $Revision: 573864 $
      4  * $Date: 2007-09-08 08:53:25 -0700 (Sat, 08 Sep 2007) $
      5  *
      6  * ====================================================================
      7  * Licensed to the Apache Software Foundation (ASF) under one
      8  * or more contributor license agreements.  See the NOTICE file
      9  * distributed with this work for additional information
     10  * regarding copyright ownership.  The ASF licenses this file
     11  * to you under the Apache License, Version 2.0 (the
     12  * "License"); you may not use this file except in compliance
     13  * with the License.  You may obtain a copy of the License at
     14  *
     15  *   http://www.apache.org/licenses/LICENSE-2.0
     16  *
     17  * Unless required by applicable law or agreed to in writing,
     18  * software distributed under the License is distributed on an
     19  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
     20  * KIND, either express or implied.  See the License for the
     21  * specific language governing permissions and limitations
     22  * under the License.
     23  * ====================================================================
     24  *
     25  * This software consists of voluntary contributions made by many
     26  * individuals on behalf of the Apache Software Foundation.  For more
     27  * information on the Apache Software Foundation, please see
     28  * <http://www.apache.org/>.
     29  *
     30  */
     31 
     32 package org.apache.http.protocol;
     33 
     34 import java.io.IOException;
     35 
     36 import org.apache.http.HttpEntity;
     37 import org.apache.http.HttpEntityEnclosingRequest;
     38 import org.apache.http.HttpException;
     39 import org.apache.http.HttpRequest;
     40 import org.apache.http.HttpRequestInterceptor;
     41 import org.apache.http.HttpVersion;
     42 import org.apache.http.ProtocolVersion;
     43 import org.apache.http.params.HttpProtocolParams;
     44 
     45 /**
     46  * A request interceptor that enables the expect-continue handshake.
     47  *
     48  * @author <a href="mailto:oleg at ural.ru">Oleg Kalnichevski</a>
     49  *
     50  * @version $Revision: 573864 $
     51  *
     52  * @since 4.0
     53  */
     54 public class RequestExpectContinue implements HttpRequestInterceptor {
     55 
     56     public RequestExpectContinue() {
     57         super();
     58     }
     59 
     60     public void process(final HttpRequest request, final HttpContext context)
     61             throws HttpException, IOException {
     62         if (request == null) {
     63             throw new IllegalArgumentException("HTTP request may not be null");
     64         }
     65         if (request instanceof HttpEntityEnclosingRequest) {
     66             HttpEntity entity = ((HttpEntityEnclosingRequest)request).getEntity();
     67             // Do not send the expect header if request body is known to be empty
     68             if (entity != null && entity.getContentLength() != 0) {
     69                 ProtocolVersion ver = request.getRequestLine().getProtocolVersion();
     70                 if (HttpProtocolParams.useExpectContinue(request.getParams())
     71                         && !ver.lessEquals(HttpVersion.HTTP_1_0)) {
     72                     request.addHeader(HTTP.EXPECT_DIRECTIVE, HTTP.EXPECT_CONTINUE);
     73                 }
     74             }
     75         }
     76     }
     77 
     78 }
     79