java.net

Class ServerSocket

java.lang.Object

java.net.ServerSocket

All Implemented Interfaces:

AutoCloseable

public class ServerSocket
extends Object
implements AutoCloseable

This class models server side sockets. The basic model is that the server socket is created and bound to some well known port. It then listens for and accepts connections. At that point the client and server sockets are ready to communicate with one another utilizing whatever application layer protocol they desire. As with the Socket class, most instance methods of this class simply redirect their calls to an implementation class.

Author:

Aaron M. Renn (arenn@urbanophile.com), Per Bothner (bothner@cygnus.com)

Constructor Summary

Constructors

Constructor and Description
ServerSocket() Constructor that simply sets the implementation.
ServerSocket(int port) Creates a server socket and binds it to the specified port.
ServerSocket(int port, int backlog) Creates a server socket and binds it to the specified port.
ServerSocket(int port, int backlog, InetAddress bindAddr) Creates a server socket and binds it to the specified port.

Method Summary

Modifier and Type	Method and Description
Socket	accept() Accepts a new connection and returns a connected Socket instance representing that connection.
void	bind(SocketAddress endpoint) Binds the server socket to a specified socket address
void	bind(SocketAddress endpoint, int backlog) Binds the server socket to a specified socket address
void	close() Closes this socket and stops listening for connections
InetAddress	getInetAddress() This method returns the local address to which this socket is bound
int	getLocalPort() This method returns the local port number to which this socket is bound
SocketAddress	getLocalSocketAddress() Returns the local socket address
int	getReceiveBufferSize() This method returns the value of the system level socket option SO_RCVBUF, which is used by the operating system to tune buffer sizes for data transfers.
boolean	getReuseAddress() Checks if the SO_REUSEADDR option is enabled
int	getSoTimeout() Retrieves the current value of the SO_TIMEOUT setting.
boolean	isBound() Returns true when the socket is bound, otherwise false
boolean	isClosed() Returns true if the socket is closed, otherwise false
void	setReceiveBufferSize(int size) This method sets the value for the system level socket option SO_RCVBUF to the specified value.
void	setReuseAddress(boolean on) Enables/Disables the SO_REUSEADDR option
void	setSoTimeout(int timeout) Sets the value of SO_TIMEOUT.
String	toString() Returns the value of this socket as a String.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

ServerSocket

public ServerSocket()
             throws IOException

Constructor that simply sets the implementation.

Throws:

IOException - If an error occurs

ServerSocket

public ServerSocket(int port)
             throws IOException

Creates a server socket and binds it to the specified port. If the port number is 0, a random free port will be chosen. The pending connection queue on this socket will be set to 50.

Parameters:

port - The port number to bind to

Throws:

IOException - If an error occurs

ServerSocket

public ServerSocket(int port,
                    int backlog)
             throws IOException

Creates a server socket and binds it to the specified port. If the port number is 0, a random free port will be chosen. The pending connection queue on this socket will be set to the value passed as arg2.

Parameters:

port - The port number to bind to

backlog - The length of the pending connection queue

Throws:

IOException - If an error occurs

ServerSocket

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

Creates a server socket and binds it to the specified port. If the port number is 0, a random free port will be chosen. The pending connection queue on this socket will be set to the value passed as backlog. The third argument specifies a particular local address to bind t or null to bind to all local address.

Parameters:

port - The port number to bind to

backlog - The length of the pending connection queue

bindAddr - The address to bind to, or null to bind to all addresses

Throws:

IOException - If an error occurs

Since:

1.1

Method Detail

accept

public Socket accept()
              throws IOException

Accepts a new connection and returns a connected Socket instance representing that connection. This method will block until a connection is available.

Returns:

socket object for the just accepted connection

Throws:

IOException - If an error occurs

SocketTimeoutException - If a timeout was previously set with setSoTimeout and the timeout has been reached

bind

public void bind(SocketAddress endpoint)
          throws IOException

Binds the server socket to a specified socket address

Parameters:

endpoint - The socket address to bind to

Throws:

IOException - If an error occurs

IllegalArgumentException - If address type is not supported

Since:

1.4

bind

public void bind(SocketAddress endpoint,
                 int backlog)
          throws IOException

Binds the server socket to a specified socket address

Parameters:

endpoint - The socket address to bind to

backlog - The length of the pending connection queue

Throws:

IOException - If an error occurs

IllegalArgumentException - If address type is not supported

Since:

1.4

close

public void close()
           throws IOException

Closes this socket and stops listening for connections

Specified by:

close in interface AutoCloseable

Throws:

IOException - If an error occurs

getInetAddress

public InetAddress getInetAddress()

This method returns the local address to which this socket is bound

Returns:

The socket's local address

getLocalPort

public int getLocalPort()

This method returns the local port number to which this socket is bound

Returns:

The socket's port number

getLocalSocketAddress

public SocketAddress getLocalSocketAddress()

Returns the local socket address

Returns:

the local socket address, null if not bound

Since:

1.4

getReceiveBufferSize

public int getReceiveBufferSize()
                         throws SocketException

This method returns the value of the system level socket option SO_RCVBUF, which is used by the operating system to tune buffer sizes for data transfers.

Returns:

The receive buffer size.

Throws:

SocketException - If an error occurs or Socket is not connected

Since:

1.4

getReuseAddress

public boolean getReuseAddress()
                        throws SocketException

Checks if the SO_REUSEADDR option is enabled

Returns:

true if SO_REUSEADDR is set, false otherwise

Throws:

SocketException - If an error occurs

Since:

1.4

getSoTimeout

public int getSoTimeout()
                 throws IOException

Retrieves the current value of the SO_TIMEOUT setting. A value of 0 implies that SO_TIMEOUT is disabled (ie, operations never time out). This is the number of milliseconds a socket operation can block before an InterruptedIOException is thrown.

Returns:

The value of SO_TIMEOUT

Throws:

IOException - If an error occurs

Since:

1.1

isBound

public boolean isBound()

Returns true when the socket is bound, otherwise false

Returns:

true if socket is bound, false otherwise

Since:

1.4

isClosed

public boolean isClosed()

Returns true if the socket is closed, otherwise false

Returns:

true if socket is closed, false otherwise

Since:

1.4

setReceiveBufferSize

public void setReceiveBufferSize(int size)
                          throws SocketException

This method sets the value for the system level socket option SO_RCVBUF to the specified value. Note that valid values for this option are specific to a given operating system.

Parameters:

size - The new receive buffer size.

Throws:

SocketException - If an error occurs or Socket is not connected

IllegalArgumentException - If size is 0 or negative

Since:

1.4

setReuseAddress

public void setReuseAddress(boolean on)
                     throws SocketException

Enables/Disables the SO_REUSEADDR option

Parameters:

on - true if SO_REUSEADDR should be enabled, false otherwise

Throws:

SocketException - If an error occurs

Since:

1.4

setSoTimeout

public void setSoTimeout(int timeout)
                  throws SocketException

Sets the value of SO_TIMEOUT. A value of 0 implies that SO_TIMEOUT is disabled (ie, operations never time out). This is the number of milliseconds a socket operation can block before an InterruptedIOException is thrown.

Parameters:

timeout - The new SO_TIMEOUT value

Throws:

SocketException - If an error occurs

Since:

1.1

toString

public String toString()

Returns the value of this socket as a String.

Overrides:

toString in class Object

Returns:

This socket represented as a String.