java.net
Class DatagramSocket

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

public class DatagramSocket

extends Object

This class represents a socket for sending and receiving datagram packets. A datagram socket is the sending or receiving point for a packet delivery service. Each packet sent or received on a datagram socket is individually addressed and routed. Multiple packets sent from one machine to another may be routed differently, and may arrive in any order. UDP broadcasts sends and receives are always enabled on a DatagramSocket.

Constructor Summary

DatagramSocket()
Constructs a datagram socket and binds it to any available port on the local host machine.

DatagramSocket(int port)
Constructs a datagram socket and binds it to the specified port on the local host machine.

DatagramSocket(int port, InetAddress laddr)
Creates a datagram socket, bound to the specified local address.

Method Summary

void	close() Closes this datagram socket.
void	connect(InetAddress address, int port)
void	disconnect()
InetAddress	getInetAddress()
InetAddress	getLocalAddress()
int	getLocalPort()
int	getPort()
int	getSoTimeout()
void	receive(DatagramPacket p) Receives a datagram packet from this socket.
void	send(DatagramPacket p) Sends a datagram packet from this socket.
void	setSoTimeout(int timeout) Enable/disable SO_TIMEOUT with the specified timeout, in milliseconds.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, toString

Constructor Detail

DatagramSocket

public DatagramSocket()
               throws SocketException

Constructs a datagram socket and binds it to any available port on the local host machine.

Throws:

SocketException - f the socket could not be opened, or the socket could not bind to the specified local port.

DatagramSocket

public DatagramSocket(int port)
               throws SocketException

Constructs a datagram socket and binds it to the specified port on the local host machine.

Parameters:

port - local port to use.

Throws:

SocketException - if the socket could not be opened, or the socket could not bind to the specified local port.

DatagramSocket

public DatagramSocket(int port,
                      InetAddress laddr)
               throws SocketException

Creates a datagram socket, bound to the specified local address. The local port must be between 0 and 65535 inclusive.

Parameters:

port - local port to use

laddr - local address to bind

Throws:

SocketException - if the socket could not be opened, or the socket could not bind to the specified local port.

Method Detail

connect

public void connect(InetAddress address,
                    int port)

disconnect

public void disconnect()

close

public void close()

Closes this datagram socket.

receive

public void receive(DatagramPacket p)
             throws IOException

Receives a datagram packet from this socket. When this method returns, the DatagramPacket's buffer is filled with the data received. The datagram packet also contains the sender's IP address, and the port number on the sender's machine. This method blocks until a datagram is received. The length field of the datagram packet object contains the length of the received message. If the message is longer than the packet's length, the message is truncated.

Parameters:

p - the DatagramPacket into which to place the incoming data.

Throws:

IOException - if an I/O error occurs.

send

public void send(DatagramPacket p)
          throws IOException

Sends a datagram packet from this socket. The DatagramPacket includes information indicating the data to be sent, its length, the IP address of the remote host, and the port number on the remote host.

Parameters:

p - the DatagramPacket to be sent.

Throws:

IOException - if an I/O error occurs.

setSoTimeout

public 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 receive() for this DatagramSocket 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.

Parameters:

timeout - the specified timeout in milliseconds.

Throws:

SocketException - if there is an error in the underlying protocol, such as a TCP error.

getSoTimeout

public int getSoTimeout()
                 throws SocketException

SocketException

getPort

public int getPort()

getLocalPort

public int getLocalPort()

getInetAddress

public InetAddress getInetAddress()

getLocalAddress

public InetAddress getLocalAddress()