socket.java

gcc3.2.1源代码

/* Socket.java -- Client socket implementation
   Copyright (C) 1998, 1999, 2000, 2002 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
 
GNU Classpath is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.

As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
module.  An independent module is a module which is not derived from
or based on this library.  If you modify this library, you may extend
this exception to your version of the library, but you are not
obligated to do so.  If you do not wish to do so, delete this
exception statement from your version. */

package java.net;

import java.io.*;

/* Written using on-line Java Platform 1.2 API Specification.
 * Status:  I believe all methods are implemented.
 */

/**
 * This class models a client site socket.  A socket is a TCP/IP endpoint
 * for network communications conceptually similar to a file handle.
 * <p>
 * This class does not actually do any work.  Instead, it redirects all of
 * its calls to a socket implementation object which implements the
 * <code>SocketImpl</code> interface.  The implementation class is 
 * instantiated by factory class that implements the 
 * <code>SocketImplFactory interface</code>.  A default
 * factory is provided, however the factory may be set by a call to
 * the <code>setSocketImplFactory</code> method.  Note that this may only be 
 * done once per virtual machine.  If a subsequent attempt is made to set the
 * factory, a <code>SocketException</code> will be thrown.
 *
 * @author Aaron M. Renn ([e-mail])
 * @author Per Bothner ([e-mail])
 */
public class Socket
{

  // Class Variables

  /**
   * This is the user SocketImplFactory for this class.  If this variable is
   * null, a default factory is used.
   */
  static SocketImplFactory factory;

  // Instance Variables

  /**
   * The implementation object to which calls are redirected
   */
  SocketImpl impl;

  // Constructors

  /**
   * Initializes a new instance of <code>Socket</code> object without 
   * connecting to a remote host.  This useful for subclasses of socket that 
   * might want this behavior.
   */
  protected Socket ()
  {
    if (factory != null)
      impl = factory.createSocketImpl();
    else
      impl = new PlainSocketImpl();
  }

  /**
   * Initializes a new instance of <code>Socket</code> object without
   * connecting to a remote host.  This is useful for subclasses of socket
   * that might want this behavior.  
   * <p>
   * Additionally, this socket will be created using the supplied
   * implementation class instead the default class or one returned by a
   * factory.  This value can be <code>null</code>, but if it is, all instance
   * methods in <code>Socket</code> should be overridden because most of them
   * rely on this value being populated.
   *
   * @param impl The <code>SocketImpl</code> to use for this
   *             <code>Socket</code>
   *
   * @exception SocketException If an error occurs
   */
  protected Socket (SocketImpl impl) throws SocketException
  {
    this.impl = impl;
  }

  /**
   * Initializes a new instance of <code>Socket</code> and connects to the 
   * hostname and port specified as arguments.
   *
   * @param host The name of the host to connect to
   * @param port The port number to connect to
   *
   * @exception UnknownHostException If the hostname cannot be resolved to a
   * network address.
   * @exception IOException If an error occurs
   */
  public Socket (String host, int port)
    throws UnknownHostException, IOException
  {
    this(InetAddress.getByName(host), port, null, 0, true);
  }

  /**
   * Initializes a new instance of <code>Socket</code> and connects to the 
   * address and port number specified as arguments.
   *
   * @param address The address to connect to
   * @param port The port number to connect to
   *
   * @exception IOException If an error occurs
   */
  public Socket (InetAddress address, int port)
    throws IOException 
  {
    this(address, port, null, 0, true);
  }

  /**
   * Initializes a new instance of <code>Socket</code> that connects to the 
   * named host on the specified port and binds to the specified local address 
   * and port.
   *
   * @param host The name of the remote host to connect to.
   * @param port The remote port to connect to.
   * @param loadAddr The local address to bind to.
   * @param localPort The local port to bind to.
   *
   * @exception SecurityException If the <code>SecurityManager</code>
   * exists and does not allow a connection to the specified host/port or
   * binding to the specified local host/port.
   * @exception IOException If a connection error occurs.
   */
  public Socket (String host, int port,
		 InetAddress localAddr, int localPort) throws IOException
  {
    this(InetAddress.getByName(host), port, localAddr, localPort, true);
  }

  /**
   * Initializes a new instance of <code>Socket</code> and connects to the 
   * address and port number specified as arguments, plus binds to the 
   * specified local address and port.
   *
   * @param address The remote address to connect to
   * @param port The remote port to connect to
   * @param localAddr The local address to connect to
   * @param localPort The local port to connect to
   *
   * @exception IOException If an error occurs
   */
  public Socket (InetAddress address, int port,
		 InetAddress localAddr, int localPort) throws IOException
  {
    this(address, port, localAddr, localPort, true);
  }

  /**
   * Initializes a new instance of <code>Socket</code> and connects to the 
   * hostname and port specified as arguments.  If the stream argument is set 
   * to <code>true</code>, then a stream socket is created.  If it is 
   * <code>false</code>, a datagram socket is created.
   *
   * @param host The name of the host to connect to
   * @param port The port to connect to
   * @param stream <code>true</code> for a stream socket, <code>false</code>
   * for a datagram socket
   *
   * @exception IOException If an error occurs
   *
   * @deprecated Use the <code>DatagramSocket</code> class to create
   * datagram oriented sockets.
   */
  public Socket (String host, int port, boolean stream) throws IOException
  {
    this(InetAddress.getByName(host), port, null, 0, stream);
  }

  /**
   * Initializes a new instance of <code>Socket</code> and connects to the 
   * address and port number specified as arguments.  If the stream param is 
   * <code>true</code>, a stream socket will be created, otherwise a datagram 
   * socket is created.
   *
   * @param host The address to connect to
   * @param port The port number to connect to
   * @param stream <code>true</code> to create a stream socket, 
   * <code>false</code> to create a datagram socket.
   *
   * @exception IOException If an error occurs
   *
   * @deprecated Use the <code>DatagramSocket</code> class to create
   * datagram oriented sockets.
   */
  public Socket (InetAddress host, int port, boolean stream) throws IOException
  {
    this(host, port, null, 0, stream);
  }

  /**
   * This constructor is where the real work takes place.  Connect to the
   * specified address and port.  Use default local values if not specified,
   * otherwise use the local host and port passed in.  Create as stream or
   * datagram based on "stream" argument.
   * <p>
   *
   * @param raddr The remote address to connect to
   * @param rport The remote port to connect to
   * @param laddr The local address to connect to
   * @param lport The local port to connect to
   * @param stream true for a stream socket, false for a datagram socket
   *
   * @exception IOException If an error occurs
   */
  private Socket(InetAddress raddr, int rport, InetAddress laddr, int lport,
                 boolean stream) throws IOException
  {
    this();
    if (impl == null)
      throw new IOException("Cannot initialize Socket implementation");

    SecurityManager sm = System.getSecurityManager();
    if (sm != null)
      sm.checkConnect(raddr.getHostName(), rport);

    impl.create(stream);

    // FIXME: JCL p. 1586 says if localPort is unspecified, bind to any port,
    // i.e. '0' and if localAddr is unspecified, use getLocalAddress() as
    // that default.  JDK 1.2 doc infers not to do a bind.
    if (laddr != null)
      impl.bind(laddr, lport);

    if (raddr != null)
      impl.connect(raddr, rport);
  }

  /**
   * Returns the address of the remote end of the socket.  If this socket
   * is not connected, then <code>null</code> is returned.
   *
   * @return The remote address this socket is connected to
   */
  public InetAddress getInetAddress ()
  {
    if (impl != null)
      return impl.getInetAddress();

    return null;
  }

  /**
   * Returns the local address to which this socket is bound.  If this socket
   * is not connected, then <code>null</code> is returned.
   *
   * @return The local address
   */
  public InetAddress getLocalAddress ()
  {
    if (impl == null)
      return null;

    InetAddress addr = null;
    try
      {
        addr = (InetAddress)impl.getOption(SocketOptions.SO_BINDADDR);
      }
    catch(SocketException e)
      {
        // (hopefully) shouldn't happen
        // throw new java.lang.InternalError
        //      ("Error in PlainSocketImpl.getOption");
        return null;
      }

    // FIXME: According to libgcj, checkConnect() is supposed to be called
    // before performing this operation.  Problems: 1) We don't have the
    // addr until after we do it, so we do a post check.  2). The docs I
    // see don't require this in the Socket case, only DatagramSocket, but
    // we'll assume they mean both.
    SecurityManager sm = System.getSecurityManager();
    if (sm != null)
      sm.checkConnect(addr.getHostName(), getLocalPort());

    return addr;
  }

  /**
   * Returns the port number of the remote end of the socket connection.  If
   * this socket is not connected, then -1 is returned.
   *
   * @return The remote port this socket is connected to
   */
  public int getPort ()
  {
    if (impl != null)
      return impl.getPort();

    return -1;
  }

  /**
   * Returns the local port number to which this socket is bound.  If this
   * socket is not connected, then -1 is returned.
   *
   * @return The local port