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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  package org.apache.http.impl.client;
28  
29  import org.apache.http.HeaderElement;
30  import org.apache.http.HeaderElementIterator;
31  import org.apache.http.HttpResponse;
32  import org.apache.http.annotation.Immutable;
33  import org.apache.http.conn.ConnectionKeepAliveStrategy;
34  import org.apache.http.message.BasicHeaderElementIterator;
35  import org.apache.http.protocol.HTTP;
36  import org.apache.http.protocol.HttpContext;
37  import org.apache.http.util.Args;
38  
39  /**
40   * Default implementation of a strategy deciding duration
41   * that a connection can remain idle.
42   *
43   * The default implementation looks solely at the 'Keep-Alive'
44   * header's timeout token.
45   *
46   * @since 4.0
47   */
48  @Immutable
49  public class DefaultConnectionKeepAliveStrategy implements ConnectionKeepAliveStrategy {
50  
51      public static final DefaultConnectionKeepAliveStrategy INSTANCE = new DefaultConnectionKeepAliveStrategy();
52  
53      public long getKeepAliveDuration(final HttpResponse response, final HttpContext context) {
54          Args.notNull(response, "HTTP response");
55          final HeaderElementIterator it = new BasicHeaderElementIterator(
56                  response.headerIterator(HTTP.CONN_KEEP_ALIVE));
57          while (it.hasNext()) {
58              final HeaderElement he = it.nextElement();
59              final String param = he.getName();
60              final String value = he.getValue();
61              if (value != null && param.equalsIgnoreCase("timeout")) {
62                  try {
63                      return Long.parseLong(value) * 1000;
64                  } catch(final NumberFormatException ignore) {
65                  }
66              }
67          }
68          return -1;
69      }
70  
71  }