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1   /*
2    * ====================================================================
3    *
4    *  Licensed to the Apache Software Foundation (ASF) under one or more
5    *  contributor license agreements.  See the NOTICE file distributed with
6    *  this work for additional information regarding copyright ownership.
7    *  The ASF licenses this file to You under the Apache License, Version 2.0
8    *  (the "License"); you may not use this file except in compliance with
9    *  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, software
14   *  distributed under the License is distributed on an "AS IS" BASIS,
15   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16   *  See the License for the specific language governing permissions and
17   *  limitations under the License.
18   * ====================================================================
19   *
20   * This software consists of voluntary contributions made by many
21   * individuals on behalf of the Apache Software Foundation.  For more
22   * information on the Apache Software Foundation, please see
23   * <http://www.apache.org/>.
24   */
25  package org.apache.http.client.protocol;
26  
27  import java.io.IOException;
28  
29  import org.apache.http.HttpException;
30  import org.apache.http.HttpRequest;
31  import org.apache.http.HttpRequestInterceptor;
32  import org.apache.http.annotation.Immutable;
33  import org.apache.http.protocol.HttpContext;
34  
35  /**
36   * Class responsible for handling Content Encoding requests in HTTP.
37   * <p>
38   * Instances of this class are stateless, therefore they're thread-safe and immutable.
39   *
40   * @see "http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.5"
41   *
42   * @since 4.1
43   */
44  @Immutable
45  public class RequestAcceptEncoding implements HttpRequestInterceptor {
46  
47      /**
48       * Adds the header {@code "Accept-Encoding: gzip,deflate"} to the request.
49       */
50      public void process(
51              final HttpRequest request,
52              final HttpContext context) throws HttpException, IOException {
53  
54          /* Signal support for Accept-Encoding transfer encodings. */
55          if (!request.containsHeader("Accept-Encoding")) {
56              request.addHeader("Accept-Encoding", "gzip,deflate");
57          } 
58      }
59  
60  }