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Commons Net example source code file (SocketClient.java)

This example Commons Net source code file (SocketClient.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Commons Net tags/keywords

default_connect_timeout, inetaddress, inetaddress, inetsocketaddress, io, ioexception, ioexception, net, network, protocolcommandsupport, protocolcommandsupport, serversocketfactory, socketclient, socketexception, socketexception, socketfactory, string

The Commons Net SocketClient.java source code

/*
 * 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.
 */

package org.apache.commons.net;

import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.SocketException;
import java.net.UnknownHostException;

import javax.net.ServerSocketFactory;
import javax.net.SocketFactory;


/**
 * The SocketClient provides the basic operations that are required of
 * client objects accessing sockets.  It is meant to be
 * subclassed to avoid having to rewrite the same code over and over again
 * to open a socket, close a socket, set timeouts, etc.  Of special note
 * is the {@link #setSocketFactory  setSocketFactory }
 * method, which allows you to control the type of Socket the SocketClient
 * creates for initiating network connections.  This is especially useful
 * for adding SSL or proxy support as well as better support for applets.  For
 * example, you could create a
 * {@link javax.net.SocketFactory} that
 * requests browser security capabilities before creating a socket.
 * All classes derived from SocketClient should use the
 * {@link #_socketFactory_  _socketFactory_ } member variable to
 * create Socket and ServerSocket instances rather than instantiating
 * them by directly invoking a constructor.  By honoring this contract
 * you guarantee that a user will always be able to provide his own
 * Socket implementations by substituting his own SocketFactory.
 * @see SocketFactory
 */
public abstract class SocketClient
{
    /**
     * The end of line character sequence used by most IETF protocols.  That
     * is a carriage return followed by a newline: "\r\n"
     */
    public static final String NETASCII_EOL = "\r\n";

    /** The default SocketFactory shared by all SocketClient instances. */
    private static final SocketFactory __DEFAULT_SOCKET_FACTORY =
            SocketFactory.getDefault();

    /** The default {@link ServerSocketFactory} */
    private static final ServerSocketFactory __DEFAULT_SERVER_SOCKET_FACTORY =
            ServerSocketFactory.getDefault();

    /**
     * A ProtocolCommandSupport object used to manage the registering of
     * ProtocolCommandListeners and te firing of ProtocolCommandEvents.
     */
    private ProtocolCommandSupport __commandSupport;

    /** The timeout to use after opening a socket. */
    protected int _timeout_;

    /** The socket used for the connection. */
    protected Socket _socket_;

    /** The default port the client should connect to. */
    protected int _defaultPort_;

    /** The socket's InputStream. */
    protected InputStream _input_;

    /** The socket's OutputStream. */
    protected OutputStream _output_;

    /** The socket's SocketFactory. */
    protected SocketFactory _socketFactory_;

    /** The socket's ServerSocket Factory. */
    protected ServerSocketFactory _serverSocketFactory_;

    /** The socket's connect timeout (0 = infinite timeout) */
    private static final int DEFAULT_CONNECT_TIMEOUT = 0;
    protected int connectTimeout = DEFAULT_CONNECT_TIMEOUT;

    /** Hint for SO_RCVBUF size */
    private int receiveBufferSize = -1;

    /** Hint for SO_SNDBUF size */
    private int sendBufferSize = -1;

    /**
     * Default constructor for SocketClient.  Initializes
     * _socket_ to null, _timeout_ to 0, _defaultPort to 0,
     * _isConnected_ to false, and _socketFactory_ to a shared instance of
     * {@link org.apache.commons.net.DefaultSocketFactory}.
     */
    public SocketClient()
    {
        _socket_ = null;
        _input_ = null;
        _output_ = null;
        _timeout_ = 0;
        _defaultPort_ = 0;
        _socketFactory_ = __DEFAULT_SOCKET_FACTORY;
        _serverSocketFactory_ = __DEFAULT_SERVER_SOCKET_FACTORY;
    }


    /**
     * Because there are so many connect() methods, the _connectAction_()
     * method is provided as a means of performing some action immediately
     * after establishing a connection, rather than reimplementing all
     * of the connect() methods.  The last action performed by every
     * connect() method after opening a socket is to call this method.
     * <p>
     * This method sets the timeout on the just opened socket to the default
     * timeout set by {@link #setDefaultTimeout  setDefaultTimeout() },
     * sets _input_ and _output_ to the socket's InputStream and OutputStream
     * respectively, and sets _isConnected_ to true.
     * <p>
     * Subclasses overriding this method should start by calling
     * <code> super._connectAction_()  first to ensure the
     * initialization of the aforementioned protected variables.
     */
    protected void _connectAction_() throws IOException
    {
        _socket_.setSoTimeout(_timeout_);
        _input_ = _socket_.getInputStream();
        _output_ = _socket_.getOutputStream();
    }


    /**
     * Opens a Socket connected to a remote host at the specified port and
     * originating from the current host at a system assigned port.
     * Before returning, {@link #_connectAction_  _connectAction_() }
     * is called to perform connection initialization actions.
     * <p>
     * @param host  The remote host.
     * @param port  The port to connect to on the remote host.
     * @exception SocketException If the socket timeout could not be set.
     * @exception IOException If the socket could not be opened.  In most
     *  cases you will only want to catch IOException since SocketException is
     *  derived from it.
     */
    public void connect(InetAddress host, int port)
    throws SocketException, IOException
    {
        _socket_ = _socketFactory_.createSocket();
        if (receiveBufferSize != -1) _socket_.setReceiveBufferSize(receiveBufferSize);
        if (sendBufferSize != -1) _socket_.setSendBufferSize(sendBufferSize);
        _socket_.connect(new InetSocketAddress(host, port), connectTimeout);
        _connectAction_();
    }

    /**
     * Opens a Socket connected to a remote host at the specified port and
     * originating from the current host at a system assigned port.
     * Before returning, {@link #_connectAction_  _connectAction_() }
     * is called to perform connection initialization actions.
     * <p>
     * @param hostname  The name of the remote host.
     * @param port  The port to connect to on the remote host.
     * @exception SocketException If the socket timeout could not be set.
     * @exception IOException If the socket could not be opened.  In most
     *  cases you will only want to catch IOException since SocketException is
     *  derived from it.
     * @exception UnknownHostException If the hostname cannot be resolved.
     */
    public void connect(String hostname, int port)
    throws SocketException, IOException
    {
        connect(InetAddress.getByName(hostname), port);
    }


    /**
     * Opens a Socket connected to a remote host at the specified port and
     * originating from the specified local address and port.
     * Before returning, {@link #_connectAction_  _connectAction_() }
     * is called to perform connection initialization actions.
     * <p>
     * @param host  The remote host.
     * @param port  The port to connect to on the remote host.
     * @param localAddr  The local address to use.
     * @param localPort  The local port to use.
     * @exception SocketException If the socket timeout could not be set.
     * @exception IOException If the socket could not be opened.  In most
     *  cases you will only want to catch IOException since SocketException is
     *  derived from it.
     */
    public void connect(InetAddress host, int port,
                        InetAddress localAddr, int localPort)
    throws SocketException, IOException
    {
        _socket_ = _socketFactory_.createSocket();
        if (receiveBufferSize != -1) _socket_.setReceiveBufferSize(receiveBufferSize);
        if (sendBufferSize != -1) _socket_.setSendBufferSize(sendBufferSize);
        _socket_.bind(new InetSocketAddress(localAddr, localPort));
        _socket_.connect(new InetSocketAddress(host, port), connectTimeout);
        _connectAction_();
    }


    /**
     * Opens a Socket connected to a remote host at the specified port and
     * originating from the specified local address and port.
     * Before returning, {@link #_connectAction_  _connectAction_() }
     * is called to perform connection initialization actions.
     * <p>
     * @param hostname  The name of the remote host.
     * @param port  The port to connect to on the remote host.
     * @param localAddr  The local address to use.
     * @param localPort  The local port to use.
     * @exception SocketException If the socket timeout could not be set.
     * @exception IOException If the socket could not be opened.  In most
     *  cases you will only want to catch IOException since SocketException is
     *  derived from it.
     * @exception UnknownHostException If the hostname cannot be resolved.
     */
    public void connect(String hostname, int port,
                        InetAddress localAddr, int localPort)
    throws SocketException, IOException
    {
       connect(InetAddress.getByName(hostname), port, localAddr, localPort);
    }


    /**
     * Opens a Socket connected to a remote host at the current default port
     * and originating from the current host at a system assigned port.
     * Before returning, {@link #_connectAction_  _connectAction_() }
     * is called to perform connection initialization actions.
     * <p>
     * @param host  The remote host.
     * @exception SocketException If the socket timeout could not be set.
     * @exception IOException If the socket could not be opened.  In most
     *  cases you will only want to catch IOException since SocketException is
     *  derived from it.
     */
    public void connect(InetAddress host) throws SocketException, IOException
    {
        connect(host, _defaultPort_);
    }


    /**
     * Opens a Socket connected to a remote host at the current default
     * port and originating from the current host at a system assigned port.
     * Before returning, {@link #_connectAction_  _connectAction_() }
     * is called to perform connection initialization actions.
     * <p>
     * @param hostname  The name of the remote host.
     * @exception SocketException If the socket timeout could not be set.
     * @exception IOException If the socket could not be opened.  In most
     *  cases you will only want to catch IOException since SocketException is
     *  derived from it.
     * @exception UnknownHostException If the hostname cannot be resolved.
     */
    public void connect(String hostname) throws SocketException, IOException
    {
        connect(hostname, _defaultPort_);
    }


    /**
     * Disconnects the socket connection.
     * You should call this method after you've finished using the class
     * instance and also before you call
     * {@link #connect connect() }
     * again.  _isConnected_ is set to false, _socket_ is set to null,
     * _input_ is set to null, and _output_ is set to null.
     * <p>
     * @exception IOException  If there is an error closing the socket.
     */
    public void disconnect() throws IOException
    {
        closeQuietly(_socket_);
        closeQuietly(_input_);
        closeQuietly(_output_);
        _socket_ = null;
        _input_ = null;
        _output_ = null;
    }

    private void closeQuietly(Socket socket) {
        if (socket != null){
            try {
                socket.close();
            } catch (IOException e) {
            }
        }
    }

    private void closeQuietly(Closeable close){
        if (close != null){
            try {
                close.close();
            } catch (IOException e) {
            }
        }
    }
    /**
     * Returns true if the client is currently connected to a server.
     * <p>
     * Delegates to {@link Socket#isConnected()}
     * @return True if the client is currently connected to a server,
     *         false otherwise.
     */
    public boolean isConnected()
    {
        if (_socket_ == null)
            return false;

        return _socket_.isConnected();
    }

    /**
     * Make various checks on the socket to test if it is available for use.
     * Note that the only sure test is to use it, but these checks may help
     * in some cases.
     * @see <a href="https://issues.apache.org/jira/browse/NET-350">NET-350
     * @return {@code true} if the socket appears to be available for use
     * @since 3.0
     */
    public boolean isAvailable(){
        if (isConnected()) {
            try
            {
                if (_socket_.getInetAddress() == null) return false;
                if (_socket_.getPort() == 0) return false;
                if (_socket_.getRemoteSocketAddress() == null) return false;
                if (_socket_.isClosed()) return false;
                /* these aren't exact checks (a Socket can be half-open),
                   but since we usually require two-way data transfer,
                   we check these here too: */
                if (_socket_.isInputShutdown()) return false;
                if (_socket_.isOutputShutdown()) return false;
                /* ignore the result, catch exceptions: */
                _socket_.getInputStream();
                _socket_.getOutputStream();
            }
            catch (IOException ioex)
            {
                return false;
            }
            return true;
        } else {
            return false;
        }
    }

    /**
     * Sets the default port the SocketClient should connect to when a port
     * is not specified.  The {@link #_defaultPort_  _defaultPort_ }
     * variable stores this value.  If never set, the default port is equal
     * to zero.
     * <p>
     * @param port  The default port to set.
     */
    public void setDefaultPort(int port)
    {
        _defaultPort_ = port;
    }

    /**
     * Returns the current value of the default port (stored in
     * {@link #_defaultPort_  _defaultPort_ }).
     * <p>
     * @return The current value of the default port.
     */
    public int getDefaultPort()
    {
        return _defaultPort_;
    }


    /**
     * Set the default timeout in milliseconds to use when opening a socket.
     * This value is only used previous to a call to
     * {@link #connect connect()}
     * and should not be confused with {@link #setSoTimeout setSoTimeout()}
     * which operates on an the currently opened socket.  _timeout_ contains
     * the new timeout value.
     * <p>
     * @param timeout  The timeout in milliseconds to use for the socket
     *                 connection.
     */
    public void setDefaultTimeout(int timeout)
    {
        _timeout_ = timeout;
    }


    /**
     * Returns the default timeout in milliseconds that is used when
     * opening a socket.
     * <p>
     * @return The default timeout in milliseconds that is used when
     *         opening a socket.
     */
    public int getDefaultTimeout()
    {
        return _timeout_;
    }


    /**
     * Set the timeout in milliseconds of a currently open connection.
     * Only call this method after a connection has been opened
     * by {@link #connect connect()}.
     * <p>
     * @param timeout  The timeout in milliseconds to use for the currently
     *                 open socket connection.
     * @exception SocketException If the operation fails.
     */
    public void setSoTimeout(int timeout) throws SocketException
    {
        _socket_.setSoTimeout(timeout);
    }


    /**
     * Set the underlying socket send buffer size.
     * <p>
     * @param size The size of the buffer in bytes.
     * @throws SocketException
     * @since 2.0
     */
    public void setSendBufferSize(int size) throws SocketException {
        sendBufferSize = size;
    }

    /**
     * Get the current sendBuffer size
     * @return the size, or -1 if not initialised
     * @since 3.0 
     */
    protected int getSendBufferSize(){
        return sendBufferSize;
    }

    /**
     * Sets the underlying socket receive buffer size.
     * <p>
     * @param size The size of the buffer in bytes.
     * @throws SocketException
     * @since 2.0
     */
    public void setReceiveBufferSize(int size) throws SocketException  {
        receiveBufferSize = size;
    }

    /**
     * Get the current receivedBuffer size
     * @return the size, or -1 if not initialised
     * @since 3.0 
     */
    protected int getReceiveBufferSize(){
        return receiveBufferSize;
    }

    /**
     * Returns the timeout in milliseconds of the currently opened socket.
     * <p>
     * @return The timeout in milliseconds of the currently opened socket.
     * @exception SocketException If the operation fails.
     */
    public int getSoTimeout() throws SocketException
    {
        return _socket_.getSoTimeout();
    }

    /**
     * Enables or disables the Nagle's algorithm (TCP_NODELAY) on the
     * currently opened socket.
     * <p>
     * @param on  True if Nagle's algorithm is to be enabled, false if not.
     * @exception SocketException If the operation fails.
     */
    public void setTcpNoDelay(boolean on) throws SocketException
    {
        _socket_.setTcpNoDelay(on);
    }


    /**
     * Returns true if Nagle's algorithm is enabled on the currently opened
     * socket.
     * <p>
     * @return True if Nagle's algorithm is enabled on the currently opened
     *        socket, false otherwise.
     * @exception SocketException If the operation fails.
     */
    public boolean getTcpNoDelay() throws SocketException
    {
        return _socket_.getTcpNoDelay();
    }

    /**
     * Sets the SO_KEEPALIVE flag on the currently opened socket.
     *
     * From the Javadocs, the default keepalive time is 2 hours (although this is
     * implementation  dependent). It looks as though the Windows WSA sockets implementation
     * allows a specific keepalive value to be set, although this seems not to be the case on
     * other systems.
     * @param  keepAlive If true, keepAlive is turned on
     * @throws SocketException
     * @since 2.2
     */
    public void setKeepAlive(boolean keepAlive) throws SocketException {
        _socket_.setKeepAlive(keepAlive);
    }

    /**
     * Returns the current value of the SO_KEEPALIVE flag on the currently opened socket.
     * Delegates to {@link Socket#getKeepAlive()}
     * @return True if SO_KEEPALIVE is enabled.
     * @throws SocketException
     * @since 2.2
     */
    public boolean getKeepAlive() throws SocketException {
        return _socket_.getKeepAlive();
    }

    /**
     * Sets the SO_LINGER timeout on the currently opened socket.
     * <p>
     * @param on  True if linger is to be enabled, false if not.
     * @param val The linger timeout (in hundredths of a second?)
     * @exception SocketException If the operation fails.
     */
    public void setSoLinger(boolean on, int val) throws SocketException
    {
        _socket_.setSoLinger(on, val);
    }


    /**
     * Returns the current SO_LINGER timeout of the currently opened socket.
     * <p>
     * @return The current SO_LINGER timeout.  If SO_LINGER is disabled returns
     *         -1.
     * @exception SocketException If the operation fails.
     */
    public int getSoLinger() throws SocketException
    {
        return _socket_.getSoLinger();
    }


    /**
     * Returns the port number of the open socket on the local host used
     * for the connection.
     * Delegates to {@link Socket#getLocalPort()}
     * <p>
     * @return The port number of the open socket on the local host used
     *         for the connection.
     */
    public int getLocalPort()
    {
        return _socket_.getLocalPort();
    }


    /**
     * Returns the local address  to which the client's socket is bound.
     * Delegates to {@link Socket#getLocalAddress()}
     * <p>
     * @return The local address to which the client's socket is bound.
     */
    public InetAddress getLocalAddress()
    {
        return _socket_.getLocalAddress();
    }

    /**
     * Returns the port number of the remote host to which the client is
     * connected.
     * Delegates to {@link Socket#getPort()}
     * <p>
     * @return The port number of the remote host to which the client is
     *         connected.
     */
    public int getRemotePort()
    {
        return _socket_.getPort();
    }


    /**
     * @return The remote address to which the client is connected.
     * Delegates to {@link Socket#getInetAddress()}
     */
    public InetAddress getRemoteAddress()
    {
        return _socket_.getInetAddress();
    }


    /**
     * Verifies that the remote end of the given socket is connected to the
     * the same host that the SocketClient is currently connected to.  This
     * is useful for doing a quick security check when a client needs to
     * accept a connection from a server, such as an FTP data connection or
     * a BSD R command standard error stream.
     * <p>
     * @return True if the remote hosts are the same, false if not.
     */
    public boolean verifyRemote(Socket socket)
    {
        InetAddress host1, host2;

        host1 = socket.getInetAddress();
        host2 = getRemoteAddress();

        return host1.equals(host2);
    }


    /**
     * Sets the SocketFactory used by the SocketClient to open socket
     * connections.  If the factory value is null, then a default
     * factory is used (only do this to reset the factory after having
     * previously altered it).
     * <p>
     * @param factory  The new SocketFactory the SocketClient should use.
     */
    public void setSocketFactory(SocketFactory factory)
    {
        if (factory == null)
            _socketFactory_ = __DEFAULT_SOCKET_FACTORY;
        else
            _socketFactory_ = factory;
    }

    /**
     * Sets the ServerSocketFactory used by the SocketClient to open ServerSocket
     * connections.  If the factory value is null, then a default
     * factory is used (only do this to reset the factory after having
     * previously altered it).
     * <p>
     * @param factory  The new ServerSocketFactory the SocketClient should use.
     * @since 2.0
     */
    public void setServerSocketFactory(ServerSocketFactory factory) {
        if (factory == null)
            _serverSocketFactory_ = __DEFAULT_SERVER_SOCKET_FACTORY;
        else
            _serverSocketFactory_ = factory;
    }

    /**
     * Sets the connection timeout in milliseconds, which will be passed to the {@link Socket} object's
     * connect() method.
     * @param connectTimeout The connection timeout to use (in ms)
     * @since 2.0
     */
    public void setConnectTimeout(int connectTimeout) {
        this.connectTimeout = connectTimeout;
    }

    /**
     * Get the underlying socket connection timeout.
     * @return timeout (in ms)
     * @since 2.0
     */
    public int getConnectTimeout() {
        return connectTimeout;
    }

    /**
     * Get the underlying {@link ServerSocketFactory}
     * @return The server socket factory
     * @since 2.2
     */
    public ServerSocketFactory getServerSocketFactory() {
        return _serverSocketFactory_;
    }


    /**
     * Adds a ProtocolCommandListener. 
     *
     * @param listener  The ProtocolCommandListener to add.
     * @since 3.0
     */
    public void addProtocolCommandListener(ProtocolCommandListener listener) {
        getCommandSupport().addProtocolCommandListener(listener);
    }

    /**
     * Removes a ProtocolCommandListener.
     *
     * @param listener  The ProtocolCommandListener to remove.
     * @since 3.0
     */
    public void removeProtocolCommandListener(ProtocolCommandListener listener) {
        getCommandSupport().removeProtocolCommandListener(listener);
    }

    /**
     * If there are any listeners, send them the reply details.
     * 
     * @param replyCode the code extracted from the reply
     * @param reply the full reply text
     * @since 3.0
     */
    protected void fireReplyReceived(int replyCode, String reply) {
        if (getCommandSupport().getListenerCount() > 0) {
            getCommandSupport().fireReplyReceived(replyCode, reply);
        }
    }

    /**
     * If there are any listeners, send them the command details.
     * 
     * @param command the command name
     * @param message the complete message, including command name
     * @since 3.0
     */
    protected void fireCommandSent(String command, String message) {
        if (getCommandSupport().getListenerCount() > 0) {
            getCommandSupport().fireCommandSent(command, message);
        }
    }

    /**
     * Create the CommandSupport instance if required
     */
    protected void createCommandSupport(){
        __commandSupport = new ProtocolCommandSupport(this);
    }

    /**
     * Subclasses can override this if they need to provide their own
     * instance field for backwards compatibilty.
     * 
     * @return the CommandSupport instance, may be {@code null}
     * @since 3.0
     */
    protected ProtocolCommandSupport getCommandSupport() {
        return __commandSupport;
    }

    /*
     *  N.B. Fields cannot be pulled up into a super-class without breaking binary compatibility,
     *  so the abstract method is needed to pass the instance to the methods which were moved here.
     */
}


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