java.net
Class DatagramPacket

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

public class DatagramPacket

extends Object

This class represents a datagram packet. Datagram packets are used to implement a connectionless packet delivery service. Each message is routed from one machine to another based solely on information contained within that packet. Multiple packets sent from one machine to another might be routed differently, and might arrive in any order.

Constructor Summary

DatagramPacket(byte[] buf, int length)
Constructs a DatagramPacket for receiving packets of length length.

DatagramPacket(byte[] buf, int length, InetAddress address, int port)
Constructs a datagram packet for sending packets of length length to the specified port number on the specified host.

DatagramPacket(byte[] buf, int offset, int length)
Constructs a DatagramPacket for receiving packets of length length, specifying an offset into the buffer.

DatagramPacket(byte[] buf, int offset, int length, InetAddress address, int port)

Method Summary

InetAddress	getAddress() Returns the IP address of the machine to which this datagram is being sent or from which the datagram was received.
byte[]	getData() Returns the data received or the data to be sent.
int	getLength() Returns the length of the data to be sent or the length of the data received.
int	getOffset() Returns the offset of the data to be sent or the offset of the data received.
int	getPort() Returns the port number on the remote host to which this datagram is being sent or from which the datagram was received.
void	setAddress(InetAddress iaddr) Sets the IP address of the machine to which this datagram is being sent.
void	setData(byte[] buf) Set the data buffer for this packet.
void	setData(byte[] buf, int offset, int length) Set the data buffer for this packet.
void	setLength(int length) Set the length for this packet.
void	setPort(int port) Sets the port number on the remote host to which this datagram is being sent.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, toString

Constructor Detail

DatagramPacket

public DatagramPacket(byte[] buf,
                      int offset,
                      int length)

Constructs a DatagramPacket for receiving packets of length length, specifying an offset into the buffer. The length argument must be less than or equal to buf.length.

Parameters:

buf - buffer for holding the incoming datagram.

offset - the offset for the buffer

length - the number of bytes to read.

DatagramPacket

public DatagramPacket(byte[] buf,
                      int length)

Constructs a DatagramPacket for receiving packets of length length. The length argument must be less than or equal to buf.length.

Parameters:

buf - buffer for holding the incoming datagram.

length - the number of bytes to read.

DatagramPacket

public DatagramPacket(byte[] buf,
                      int offset,
                      int length,
                      InetAddress address,
                      int port)

DatagramPacket

public DatagramPacket(byte[] buf,
                      int length,
                      InetAddress address,
                      int port)

Constructs a datagram packet for sending packets of length length to the specified port number on the specified host. The length argument must be less than or equal to buf.length.

Parameters:

buf - the packet data.

length - the packet length.

address - the destination address.

port - the destination port number.

Method Detail

getAddress

public InetAddress getAddress()

Returns the IP address of the machine to which this datagram is being sent or from which the datagram was received.

Returns:

the IP address of the machine to which this datagram is being sent or from which the datagram was received.

getData

public byte[] getData()

Returns the data received or the data to be sent.

Returns:

the data received or the data to be sent.

getLength

public int getLength()

Returns the length of the data to be sent or the length of the data received.

Returns:

the length of the data to be sent or the length of the data received.

getOffset

public int getOffset()

Returns the offset of the data to be sent or the offset of the data received.

Returns:

the offset of the data to be sent or the offset of the data received.

getPort

public int getPort()

Returns the port number on the remote host to which this datagram is being sent or from which the datagram was received.

Returns:

the port number on the remote host to which this datagram is being sent or from which the datagram was received.

setAddress

public void setAddress(InetAddress iaddr)

Sets the IP address of the machine to which this datagram is being sent.

Parameters:

iaddr - the InetAddress

setData

public void setData(byte[] buf)
             throws NullPointerException

Set the data buffer for this packet. If the length of the packet length is greater than the length of argument to this method, the length is reset to the the length of the argument.

Parameters:

buf - the buffer to set for this packet.

Throws:

NullPointerException - if the argument is null.

setData

public void setData(byte[] buf,
                    int offset,
                    int length)
             throws NullPointerException

Set the data buffer for this packet. This sets the data, length and offset of the packet.

Parameters:

buf - the buffer to set for this packet

offset - the offset into the data

length - the length of the data

Throws:

NullPointerException - if the argument is null

setLength

public void setLength(int length)
               throws IllegalArgumentException

Set the length for this packet. The length of the packet is the number of bytes from the packet's data buffer that will be sent, or the number of bytes of the packet's data buffer that will be used for receiving data. The length must be lesser or equal to the length of the packet's buffer.

Parameters:

length - the length to set for this packet.

Throws:

IllegalArgumentException - if the length is negative of if the length is greater than the packet's data buffer length.

setPort

public void setPort(int port)

Sets the port number on the remote host to which this datagram is being sent.