1   /*
    2    * $HeadURL: https://svn.apache.org/repos/asf/httpcomponents/httpcore/tags/4.0.1/httpcore/src/main/java/org/apache/http/protocol/ResponseContent.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.HttpException;
   38   import org.apache.http.HttpResponse;
   39   import org.apache.http.HttpResponseInterceptor;
   40   import org.apache.http.HttpStatus;
   41   import org.apache.http.HttpVersion;
   42   import org.apache.http.ProtocolVersion;
   43   import org.apache.http.ProtocolException;
   44   
   45   /**
   46    * ResponseContent is the most important interceptor for outgoing responses. 
   47    * It is responsible for delimiting content length by adding 
   48    * <code>Content-Length</code> or <code>Transfer-Content</code> headers based 
   49    * on the properties of the enclosed entity and the protocol version. 
   50    * This interceptor is required for correct functioning of server side protocol 
   51    * processors.
   52    *
   53    *
   54    * @version $Revision: 744532 $
   55    * 
   56    * @since 4.0
   57    */
   58   public class ResponseContent implements HttpResponseInterceptor {
   59   
   60       public ResponseContent() {
   61           super();
   62       }
   63       
   64       public void process(final HttpResponse response, final HttpContext context) 
   65               throws HttpException, IOException {
   66           if (response == null) {
   67               throw new IllegalArgumentException("HTTP request may not be null");
   68           }
   69           if (response.containsHeader(HTTP.TRANSFER_ENCODING)) {
   70               throw new ProtocolException("Transfer-encoding header already present");
   71           }
   72           if (response.containsHeader(HTTP.CONTENT_LEN)) {
   73               throw new ProtocolException("Content-Length header already present");
   74           }
   75           ProtocolVersion ver = response.getStatusLine().getProtocolVersion();
   76           HttpEntity entity = response.getEntity();
   77           if (entity != null) {
   78               long len = entity.getContentLength();
   79               if (entity.isChunked() && !ver.lessEquals(HttpVersion.HTTP_1_0)) {
   80                   response.addHeader(HTTP.TRANSFER_ENCODING, HTTP.CHUNK_CODING);
   81               } else if (len >= 0) {
   82                   response.addHeader(HTTP.CONTENT_LEN, Long.toString(entity.getContentLength()));
   83               }
   84               // Specify a content type if known
   85               if (entity.getContentType() != null && !response.containsHeader(
   86                       HTTP.CONTENT_TYPE )) {
   87                   response.addHeader(entity.getContentType()); 
   88               }
   89               // Specify a content encoding if known
   90               if (entity.getContentEncoding() != null && !response.containsHeader(
   91                       HTTP.CONTENT_ENCODING)) {
   92                   response.addHeader(entity.getContentEncoding()); 
   93               }
   94           } else {
   95               int status = response.getStatusLine().getStatusCode();
   96               if (status != HttpStatus.SC_NO_CONTENT 
   97                       && status != HttpStatus.SC_NOT_MODIFIED
   98                       && status != HttpStatus.SC_RESET_CONTENT) {
   99                   response.addHeader(HTTP.CONTENT_LEN, "0");
  100               }
  101           }
  102       }
  103       
  104   }