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Class java.net.DatagramSocket

java.lang.Object
    |
    +----java.net.DatagramSocket
Subclasses:
MulticastSocket

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 connectionless 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.

Since:
JDK1.0
See Also:
DatagramPacket

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.
InetAddress  getLocalAddress()
Gets the local address to which the socket is bound.
int  getLocalPort()
Returns the port number on the local host to which this socket is bound.
int  getSoTimeout()
Retrive setting for SO_TIMEOUT.
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
 clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

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 - if 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:
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
Method Detail

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.
See Also:
DatagramPacket

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 buffer length, the message is truncated.

Parameters:
p - the DatagramPacket into which to place the incoming data.
Throws:
IOException - if an I/O error occurs.
See Also:
DatagramPacket, DatagramSocket

getLocalAddress

public InetAddress getLocalAddress()
Gets the local address to which the socket is bound.

getLocalPort

public int getLocalPort()
Returns the port number on the local host to which this socket is bound.
Returns:
the port number on the local host to which this socket is bound.

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.

getSoTimeout

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

close

public void close()
Closes this datagram socket.

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