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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.HttpException;
33  import org.apache.http.HttpRequest;
34  import org.apache.http.HttpRequestInterceptor;
35  import org.apache.http.annotation.Immutable;
36  import org.apache.http.util.Args;
37  
38  /**
39   * RequestConnControl is responsible for adding <code>Connection</code> header
40   * to the outgoing requests, which is essential for managing persistence of
41   * <code>HTTP/1.0</code> connections. This interceptor is recommended for
42   * client side protocol processors.
43   *
44   * @since 4.0
45   */
46  @Immutable
47  public class RequestConnControl implements HttpRequestInterceptor {
48  
49      public RequestConnControl() {
50          super();
51      }
52  
53      public void process(final HttpRequest request, final HttpContext context)
54              throws HttpException, IOException {
55          Args.notNull(request, "HTTP request");
56  
57          final String method = request.getRequestLine().getMethod();
58          if (method.equalsIgnoreCase("CONNECT")) {
59              return;
60          }
61  
62          if (!request.containsHeader(HTTP.CONN_DIRECTIVE)) {
63              // Default policy is to keep connection alive
64              // whenever possible
65              request.addHeader(HTTP.CONN_DIRECTIVE, HTTP.CONN_KEEP_ALIVE);
66          }
67      }
68  
69  }