001/*
002 * ====================================================================
003 * Licensed to the Apache Software Foundation (ASF) under one
004 * or more contributor license agreements.  See the NOTICE file
005 * distributed with this work for additional information
006 * regarding copyright ownership.  The ASF licenses this file
007 * to you under the Apache License, Version 2.0 (the
008 * "License"); you may not use this file except in compliance
009 * with the License.  You may obtain a copy of the License at
010 *
011 *   http://www.apache.org/licenses/LICENSE-2.0
012 *
013 * Unless required by applicable law or agreed to in writing,
014 * software distributed under the License is distributed on an
015 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
016 * KIND, either express or implied.  See the License for the
017 * specific language governing permissions and limitations
018 * under the License.
019 * ====================================================================
020 *
021 * This software consists of voluntary contributions made by many
022 * individuals on behalf of the Apache Software Foundation.  For more
023 * information on the Apache Software Foundation, please see
024 * <http://www.apache.org/>.
025 *
026 */
027package org.apache.http.impl.client;
028
029import org.apache.http.HeaderElement;
030import org.apache.http.HeaderElementIterator;
031import org.apache.http.HttpResponse;
032import org.apache.http.annotation.Contract;
033import org.apache.http.annotation.ThreadingBehavior;
034import org.apache.http.conn.ConnectionKeepAliveStrategy;
035import org.apache.http.message.BasicHeaderElementIterator;
036import org.apache.http.protocol.HTTP;
037import org.apache.http.protocol.HttpContext;
038import org.apache.http.util.Args;
039
040/**
041 * Default implementation of a strategy deciding duration
042 * that a connection can remain idle.
043 *
044 * The default implementation looks solely at the 'Keep-Alive'
045 * header's timeout token.
046 *
047 * @since 4.0
048 */
049@Contract(threading = ThreadingBehavior.IMMUTABLE)
050public class DefaultConnectionKeepAliveStrategy implements ConnectionKeepAliveStrategy {
051
052    public static final DefaultConnectionKeepAliveStrategy INSTANCE = new DefaultConnectionKeepAliveStrategy();
053
054    @Override
055    public long getKeepAliveDuration(final HttpResponse response, final HttpContext context) {
056        Args.notNull(response, "HTTP response");
057        final HeaderElementIterator it = new BasicHeaderElementIterator(
058                response.headerIterator(HTTP.CONN_KEEP_ALIVE));
059        while (it.hasNext()) {
060            final HeaderElement he = it.nextElement();
061            final String param = he.getName();
062            final String value = he.getValue();
063            if (value != null && param.equalsIgnoreCase("timeout")) {
064                try {
065                    return Long.parseLong(value) * 1000;
066                } catch(final NumberFormatException ignore) {
067                }
068            }
069        }
070        return -1;
071    }
072
073}