http://hc.apache.org/httpcomponents-client: Apache HttpComponents Client (The Apache Software Foundation)
  • Julius Davies
  • Andrea Selva
  • Steffen Pingel
  • Quintin Beukes
  • Marc Beyerle
  • James Abley
  • Michajlo Matijkiw 
/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.http.impl.conn;

import java.io.IOException;
import java.net.ConnectException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.UnknownHostException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.http.HttpHost;
import org.apache.http.annotation.Contract;
import org.apache.http.annotation.ThreadingBehavior;
import org.apache.http.client.protocol.ClientContext;
import org.apache.http.conn.ClientConnectionOperator;
import org.apache.http.conn.ConnectTimeoutException;
import org.apache.http.conn.DnsResolver;
import org.apache.http.conn.HttpInetSocketAddress;
import org.apache.http.conn.OperatedClientConnection;
import org.apache.http.conn.scheme.Scheme;
import org.apache.http.conn.scheme.SchemeLayeredSocketFactory;
import org.apache.http.conn.scheme.SchemeRegistry;
import org.apache.http.conn.scheme.SchemeSocketFactory;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams;
import org.apache.http.protocol.HttpContext;
import org.apache.http.util.Args;
import org.apache.http.util.Asserts;


Default implementation of a ClientConnectionOperator. It uses a SchemeRegistry to look up SchemeSocketFactory objects. 
 This connection operator is multihome network aware and will attempt to retry failed connects against all known IP addresses sequentially until the connect is successful or all known addresses fail to respond. Please note the same CoreConnectionPNames.CONNECTION_TIMEOUT value will be used for each connection attempt, so in the worst case the total elapsed time before timeout can be CONNECTION_TIMEOUT * n where n is the number of IP addresses of the given host. One can disable multihome support by overriding the resolveHostname(String) method and returning only one IP address for the given host name. 

The following parameters can be used to customize the behavior of this
class:



Since:4.0
Deprecated:(4.3) use PoolingHttpClientConnectionManager.
/**
 * Default implementation of a {@link ClientConnectionOperator}. It uses a {@link SchemeRegistry}
 * to look up {@link SchemeSocketFactory} objects.
 * <p>
 * This connection operator is multihome network aware and will attempt to retry failed connects
 * against all known IP addresses sequentially until the connect is successful or all known
 * addresses fail to respond. Please note the same
 * {@link org.apache.http.params.CoreConnectionPNames#CONNECTION_TIMEOUT} value will be used
 * for each connection attempt, so in the worst case the total elapsed time before timeout
 * can be {@code CONNECTION_TIMEOUT * n} where {@code n} is the number of IP addresses
 * of the given host. One can disable multihome support by overriding
 * the {@link #resolveHostname(String)} method and returning only one IP address for the given
 * host name.
 * <p>
 * The following parameters can be used to customize the behavior of this
 * class:
 * <ul>
 *  <li>{@link org.apache.http.params.CoreProtocolPNames#HTTP_ELEMENT_CHARSET}</li>
 *  <li>{@link org.apache.http.params.CoreConnectionPNames#SO_TIMEOUT}</li>
 *  <li>{@link org.apache.http.params.CoreConnectionPNames#SO_LINGER}</li>
 *  <li>{@link org.apache.http.params.CoreConnectionPNames#SO_REUSEADDR}</li>
 *  <li>{@link org.apache.http.params.CoreConnectionPNames#TCP_NODELAY}</li>
 *  <li>{@link org.apache.http.params.CoreConnectionPNames#SOCKET_BUFFER_SIZE}</li>
 *  <li>{@link org.apache.http.params.CoreConnectionPNames#CONNECTION_TIMEOUT}</li>
 *  <li>{@link org.apache.http.params.CoreConnectionPNames#MAX_LINE_LENGTH}</li>
 * </ul>
 *
 * @since 4.0
 *
 * @deprecated (4.3) use {@link PoolingHttpClientConnectionManager}.
 */
@Deprecated
@Contract(threading = ThreadingBehavior.SAFE_CONDITIONAL)
public class DefaultClientConnectionOperator implements ClientConnectionOperator {

    private final Log log = LogFactory.getLog(getClass());

    
The scheme registry for looking up socket factories. 
/** The scheme registry for looking up socket factories. */
    protected final SchemeRegistry schemeRegistry; // @Contract(threading = ThreadingBehavior.SAFE)

    
the custom-configured DNS lookup mechanism. 
/** the custom-configured DNS lookup mechanism. */
    protected final DnsResolver dnsResolver;

    
Creates a new client connection operator for the given scheme registry.

Params:
  • schemes –   the scheme registry
Since:4.2
/**
     * Creates a new client connection operator for the given scheme registry.
     *
     * @param schemes   the scheme registry
     *
     * @since 4.2
     */
    public DefaultClientConnectionOperator(final SchemeRegistry schemes) {
        Args.notNull(schemes, "Scheme registry");
        this.schemeRegistry = schemes;
        this.dnsResolver = new SystemDefaultDnsResolver();
    }

    
Creates a new client connection operator for the given scheme registry
and the given custom DNS lookup mechanism.

Params:
  • schemes – 
           the scheme registry
  • dnsResolver – 
           the custom DNS lookup mechanism
/**
    * Creates a new client connection operator for the given scheme registry
    * and the given custom DNS lookup mechanism.
    *
    * @param schemes
    *            the scheme registry
    * @param dnsResolver
    *            the custom DNS lookup mechanism
    */
    public DefaultClientConnectionOperator(final SchemeRegistry schemes,final DnsResolver dnsResolver) {
        Args.notNull(schemes, "Scheme registry");

        Args.notNull(dnsResolver, "DNS resolver");

        this.schemeRegistry = schemes;
        this.dnsResolver = dnsResolver;
    }

    @Override
    public OperatedClientConnection createConnection() {
        return new DefaultClientConnection();
    }

    private SchemeRegistry getSchemeRegistry(final HttpContext context) {
        SchemeRegistry reg = (SchemeRegistry) context.getAttribute(
                ClientContext.SCHEME_REGISTRY);
        if (reg == null) {
            reg = this.schemeRegistry;
        }
        return reg;
    }

    @Override
    public void openConnection(
            final OperatedClientConnection conn,
            final HttpHost target,
            final InetAddress local,
            final HttpContext context,
            final HttpParams params) throws IOException {
        Args.notNull(conn, "Connection");
        Args.notNull(target, "Target host");
        Args.notNull(params, "HTTP parameters");
        Asserts.check(!conn.isOpen(), "Connection must not be open");

        final SchemeRegistry registry = getSchemeRegistry(context);
        final Scheme schm = registry.getScheme(target.getSchemeName());
        final SchemeSocketFactory sf = schm.getSchemeSocketFactory();

        final InetAddress[] addresses = resolveHostname(target.getHostName());
        final int port = schm.resolvePort(target.getPort());
        for (int i = 0; i < addresses.length; i++) {
            final InetAddress address = addresses[i];
            final boolean last = i == addresses.length - 1;

            Socket sock = sf.createSocket(params);
            conn.opening(sock, target);

            final InetSocketAddress remoteAddress = new HttpInetSocketAddress(target, address, port);
            InetSocketAddress localAddress = null;
            if (local != null) {
                localAddress = new InetSocketAddress(local, 0);
            }
            if (this.log.isDebugEnabled()) {
                this.log.debug("Connecting to " + remoteAddress);
            }
            try {
                final Socket connsock = sf.connectSocket(sock, remoteAddress, localAddress, params);
                if (sock != connsock) {
                    sock = connsock;
                    conn.opening(sock, target);
                }
                prepareSocket(sock, context, params);
                conn.openCompleted(sf.isSecure(sock), params);
                return;
            } catch (final ConnectException ex) {
                if (last) {
                    throw ex;
                }
            } catch (final ConnectTimeoutException ex) {
                if (last) {
                    throw ex;
                }
            }
            if (this.log.isDebugEnabled()) {
                this.log.debug("Connect to " + remoteAddress + " timed out. " +
                        "Connection will be retried using another IP address");
            }
        }
    }

    @Override
    public void updateSecureConnection(
            final OperatedClientConnection conn,
            final HttpHost target,
            final HttpContext context,
            final HttpParams params) throws IOException {
        Args.notNull(conn, "Connection");
        Args.notNull(target, "Target host");
        Args.notNull(params, "Parameters");
        Asserts.check(conn.isOpen(), "Connection must be open");

        final SchemeRegistry registry = getSchemeRegistry(context);
        final Scheme schm = registry.getScheme(target.getSchemeName());
        Asserts.check(schm.getSchemeSocketFactory() instanceof SchemeLayeredSocketFactory,
            "Socket factory must implement SchemeLayeredSocketFactory");
        final SchemeLayeredSocketFactory lsf = (SchemeLayeredSocketFactory) schm.getSchemeSocketFactory();
        final Socket sock = lsf.createLayeredSocket(
                conn.getSocket(), target.getHostName(), schm.resolvePort(target.getPort()), params);
        prepareSocket(sock, context, params);
        conn.update(sock, target, lsf.isSecure(sock), params);
    }

    
Performs standard initializations on a newly created socket.

Params:
  • sock –      the socket to prepare
  • context –   the context for the connection
  • params –    the parameters from which to prepare the socket
Throws:
/**
     * Performs standard initializations on a newly created socket.
     *
     * @param sock      the socket to prepare
     * @param context   the context for the connection
     * @param params    the parameters from which to prepare the socket
     *
     * @throws IOException      in case of an IO problem
     */
    protected void prepareSocket(
            final Socket sock,
            final HttpContext context,
            final HttpParams params) throws IOException {
        sock.setTcpNoDelay(HttpConnectionParams.getTcpNoDelay(params));
        sock.setSoTimeout(HttpConnectionParams.getSoTimeout(params));

        final int linger = HttpConnectionParams.getLinger(params);
        if (linger >= 0) {
            sock.setSoLinger(linger > 0, linger);
        }
    }

    
Resolves the given host name to an array of corresponding IP addresses, based on the
configured name service on the provided DNS resolver. If one wasn't provided, the system
configuration is used.

Params:
  • host – host name to resolve
Throws:
See Also:
Returns:array of IP addresses
Since:4.1
/**
     * Resolves the given host name to an array of corresponding IP addresses, based on the
     * configured name service on the provided DNS resolver. If one wasn't provided, the system
     * configuration is used.
     *
     * @param host host name to resolve
     * @return array of IP addresses
     * @throws  UnknownHostException  if no IP address for the host could be determined.
     *
     * @see DnsResolver
     * @see SystemDefaultDnsResolver
     *
     * @since 4.1
     */
    protected InetAddress[] resolveHostname(final String host) throws UnknownHostException {
            return dnsResolver.resolve(host);
    }

}