1   /*
    2    * $HeadURL: https://svn.apache.org/repos/asf/httpcomponents/httpcore/tags/4.0.1/httpcore/src/main/java/org/apache/http/protocol/RequestExpectContinue.java $
    3    * $Revision: 744532 $
    4    * $Date: 2009-02-14 18:12:18 +0100 (Sat, 14 Feb 2009) $
    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    * RequestExpectContinue is responsible for enabling the 'expect-continue' 
   47    * handshake by adding <code>Expect</code> header. This interceptor is 
   48    * recommended for client side protocol processors. 
   49    *
   50    *
   51    * @version $Revision: 744532 $
   52    * 
   53    * @since 4.0
   54    */
   55   public class RequestExpectContinue implements HttpRequestInterceptor {
   56   
   57       public RequestExpectContinue() {
   58           super();
   59       }
   60       
   61       public void process(final HttpRequest request, final HttpContext context) 
   62               throws HttpException, IOException {
   63           if (request == null) {
   64               throw new IllegalArgumentException("HTTP request may not be null");
   65           }
   66           if (request instanceof HttpEntityEnclosingRequest) {
   67               HttpEntity entity = ((HttpEntityEnclosingRequest)request).getEntity();
   68               // Do not send the expect header if request body is known to be empty
   69               if (entity != null && entity.getContentLength() != 0) { 
   70                   ProtocolVersion ver = request.getRequestLine().getProtocolVersion();
   71                   if (HttpProtocolParams.useExpectContinue(request.getParams()) 
   72                           && !ver.lessEquals(HttpVersion.HTTP_1_0)) {
   73                       request.addHeader(HTTP.EXPECT_DIRECTIVE, HTTP.EXPECT_CONTINUE);
   74                   }
   75               }
   76           }
   77       }
   78       
   79   }