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# Class java.net.ServerSocket

    java.lang.Object
       |
       +----java.net.ServerSocket

public class ServerSocket
extends Object

This class implements server sockets. A server socket waits for requests to come in over the network. It performs some operation based on that request, and then possibly returns a result to the requester.

The actual work of the server socket is performed by an instance of the `SocketImpl` class. An application can change the socket factory that creates the socket implementation to configure itself to create sockets appropriate to the local firewall.

See Also:
  SocketImpl, setSocketFactory

##

ServerSocket(int)
  Creates a server socket on a specified port.
ServerSocket(int, int)
  Creates a server socket and binds it to the specified local port number.
ServerSocket(int, int, InetAddress)
  Create a server with the specified port, listen backlog, and local IP address to bind to.

##

accept()
  Listens for a connection to be made to this socket and accepts it.
close()
  Closes this socket.
getInetAddress()
  Returns the local address of this server socket.
getLocalPort()
  Returns the port on which this socket is listening.
getSoTimeout()
  Retrive setting for SO_TIMEOUT.
implAccept(Socket)
  Subclasses of ServerSocket use this method to override accept() to return their own subclass of socket.
setSocketFactory(SocketImplFactory)
  Sets the server socket implementation factory for the application.
setSoTimeout(int)
  Enable/disable SO_TIMEOUT with the specified timeout, in milliseconds.
toString()
  Returns the implementation address and implementation port of this socket as a `String`.

##

ServerSocket

     public ServerSocket(int port) throws IOException

  Creates a server socket on a specified port. A port of `0` creates a socket on any free port.

  The maximum queue length for incoming connection indications (a request to connect) is set to `50`. If a connection indication arrives when the queue is full, the connection is refused.

  If the application has specified a server socket factory, that factory's `createSocketImpl` method is called to create the actual socket implementation. Otherwise a "plain" socket is created.

  Parameters:
    port - the port number, or `0` to use any free port.
  Throws: IOException
    if an I/O error occurs when opening the socket.
  See Also:
    SocketImpl, createSocketImpl, setSocketFactory

ServerSocket

     public ServerSocket(int port,
                         int backlog) throws IOException

  Creates a server socket and binds it to the specified local port number. A port number of `0` creates a socket on any free port.

  The maximum queue length for incoming connection indications (a request to connect) is set to the `count` parameter. If a connection indication arrives when the queue is full, the connection is refused.

  If the application has specified a server socket factory, that factory's `createSocketImpl` method is called to create the actual socket implementation. Otherwise a "plain" socket is created.

  Parameters:
    port - the specified port, or `0` to use any free port.
    backlog - the maximum length of the queue.
  Throws: IOException
    if an I/O error occurs when opening the socket.
  See Also:
    SocketImpl, createSocketImpl, setSocketFactory

ServerSocket

     public ServerSocket(int port,
                         int backlog,
                         InetAddress bindAddr) throws IOException

  Create a server with the specified port, listen backlog, and local IP address to bind to. The bindAddr argument can be used on a multi-homed host for a ServerSocket that will only accept connect requests to one of its addresses. If bindAddr is null, it will default accepting connections on any/all local addresses. The port must be between 0 and 65535, inclusive.

  Parameters:
    port - the local TCP port
    backlog - the listen backlog
    bindAddr - the local InetAddress the server will bind to
  See Also:
    SocketConstants, SocketOption, SocketImpl, 1

##

getInetAddress

     public InetAddress getInetAddress()

  Returns the local address of this server socket.

  Returns:
    the address to which this socket is connected, or `null` if the socket is not yet connected.

getLocalPort

     public int getLocalPort()

  Returns the port on which this socket is listening.

  Returns:
    the port number to which this socket is listening.

accept

     public Socket accept() throws IOException

  Listens for a connection to be made to this socket and accepts it. The method blocks until a connection is made.

  Throws: IOException
    if an I/O error occurs when waiting for a connection.

implAccept

     protected final void implAccept(Socket s) throws IOException

  Subclasses of ServerSocket use this method to override accept() to return their own subclass of socket. So a FooServerSocket will typically hand this method an empty FooSocket(). On return from implAccept the FooSocket will be connected to a client.

close

     public void close() throws IOException

  Closes this socket.

  Throws: IOException
    if an I/O error occurs when closing the socket.

setSoTimeout

     public synchronized void setSoTimeout(int timeout) throws SocketException

  Enable/disable SO_TIMEOUT with the specified timeout, in milliseconds. With this option set to a non-zero timeout, a call to accept() for this ServerSocket will block for only this amount of time. If the timeout expires, a java.io.InterruptedIOException is raised, though the ServerSocket is still valid. The option must be enabled prior to entering the blocking operation to have effect. The timeout must be > 0. A timeout of zero is interpreted as an infinite timeout.

getSoTimeout

     public synchronized int getSoTimeout() throws IOException

  Retrive setting for SO_TIMEOUT. 0 returns implies that the option is disabled (i.e., timeout of infinity).

toString

     public String toString()

  Returns the implementation address and implementation port of this socket as a `String`.

  Returns:
    a string representation of this socket.
  Overrides:
    toString in class Object

setSocketFactory

     public static synchronized void setSocketFactory(SocketImplFactory fac) throws IOException

  Sets the server socket implementation factory for the application. The factory can be specified only once.

  When an application creates a new server socket, the socket implementation factory's `createSocketImpl` method is called to create the actual socket implementation.

  Parameters:
    fac - the desired factory.
  Throws: IOException
    if an I/O error occurs when setting the socket factory.
  Throws: SocketException
    if the factory has already been defined.
  See Also:
    createSocketImpl

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