java.net

Class DatagramSocket

public class DatagramSocket extends Object

This class models a connectionless datagram socket that sends individual packets of data across the network. In the TCP/IP world, this means UDP. Datagram packets do not have guaranteed delivery, or any guarantee about the order the data will be received on the remote host.

UNKNOWN: May 3, 1999.

Constructor Summary
protected	DatagramSocket(DatagramSocketImpl impl) Creates a `DatagramSocket` from a specified `DatagramSocketImpl` instance
	DatagramSocket() Initializes a new instance of `DatagramSocket` that binds to a random port and every address on the local machine.
	DatagramSocket(int port) Initializes a new instance of `DatagramSocket` that binds to the specified port and every address on the local machine.
	DatagramSocket(int port, InetAddress addr) Initializes a new instance of `DatagramSocket` that binds to the specified local port and address.
	DatagramSocket(SocketAddress address) Initializes a new instance of `DatagramSocket` that binds to the specified local port and address.

Method Summary
void	bind(SocketAddress address) Binds the socket to the given socket address.
void	close() Closes this datagram socket.
void	connect(InetAddress address, int port) This method connects this socket to the specified address and port.
void	connect(SocketAddress address) Connects the datagram socket to a specified socket address.
void	disconnect() This method disconnects this socket from the address/port it was connected to.
boolean	getBroadcast() Checks if SO_BROADCAST is enabled
DatagramChannel	getChannel() Returns the datagram channel assoziated with this datagram socket.
InetAddress	getInetAddress() This method returns the remote address to which this socket is connected.
InetAddress	getLocalAddress() Returns the local address this datagram socket is bound to.
int	getLocalPort() Returns the local port this socket is bound to.
SocketAddress	getLocalSocketAddress() Returns the local SocketAddress this socket is bound to.
int	getPort() This method returns the remote port to which this socket is connected.
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.
SocketAddress	getRemoteSocketAddress() Returns the SocketAddress of the host this socket is conneted to or null if this socket is not connected.
boolean	getReuseAddress() Checks if SO_REUSEADDR is enabled.
int	getSendBufferSize() This method returns the value of the system level socket option SO_SNDBUF, which is used by the operating system to tune buffer sizes for data transfers.
int	getSoTimeout() Returns the value of the socket's SO_TIMEOUT setting.
int	getTrafficClass() Returns the current traffic class
boolean	isBound() Returns the binding state of the socket.
boolean	isClosed() Checks if the datagram socket is closed.
boolean	isConnected() Returns the connection state of the socket.
void	receive(DatagramPacket p) Reads a datagram packet from the socket.
void	send(DatagramPacket p) Sends the specified packet.
void	setBroadcast(boolean enable) Enables/Disables SO_BROADCAST
static void	setDatagramSocketImplFactory(DatagramSocketImplFactory fac) Sets the datagram socket implementation factory for the application
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 SO_REUSEADDR.
void	setSendBufferSize(int size) This method sets the value for the system level socket option SO_SNDBUF to the specified value.
void	setSoTimeout(int timeout) Sets the value of the socket's SO_TIMEOUT value.
void	setTrafficClass(int tc) Sets the traffic class value

Constructor Detail

DatagramSocket

protected DatagramSocket(DatagramSocketImpl impl)

Creates a DatagramSocket from a specified DatagramSocketImpl instance

Parameters: impl The DatagramSocketImpl the socket will be created from

Since: 1.4

DatagramSocket

public DatagramSocket()

Initializes a new instance of DatagramSocket that binds to a random port and every address on the local machine.

Throws: SocketException If an error occurs. SecurityException If a security manager exists and its checkListen method doesn't allow the operation.

DatagramSocket

public DatagramSocket(int port)

Initializes a new instance of DatagramSocket that binds to the specified port and every address on the local machine.

Parameters: port The local port number to bind to.

Throws: SecurityException If a security manager exists and its checkListen method doesn't allow the operation. SocketException If an error occurs.

DatagramSocket

public DatagramSocket(int port, InetAddress addr)

Initializes a new instance of DatagramSocket that binds to the specified local port and address.

Parameters: port The local port number to bind to. addr The local address to bind to.

Throws: SecurityException If a security manager exists and its checkListen method doesn't allow the operation. SocketException If an error occurs.

DatagramSocket

public DatagramSocket(SocketAddress address)

Initializes a new instance of DatagramSocket that binds to the specified local port and address.

Parameters: address The local address and port number to bind to.

Throws: SecurityException If a security manager exists and its checkListen method doesn't allow the operation. SocketException If an error occurs.

Since: 1.4

Method Detail

bind

public void bind(SocketAddress address)

Binds the socket to the given socket address.

Parameters: address The socket address to bind to.

Throws: SocketException If an error occurs. SecurityException If a security manager exists and its checkListen method doesn't allow the operation. IllegalArgumentException If address type is not supported.

Since: 1.4

close

public void close()

Closes this datagram socket.

connect

public void connect(InetAddress address, int port)

This method connects this socket to the specified address and port. When a datagram socket is connected, it will only send or receive packets to and from the host to which it is connected. A multicast socket that is connected may only send and not receive packets.

Parameters: address The address to connect this socket to. port The port to connect this socket to.

Throws: IllegalArgumentException If address or port are invalid. SecurityException If the caller is not allowed to send datagrams to or receive from this address and port.

Since: 1.2

connect

public void connect(SocketAddress address)

Connects the datagram socket to a specified socket address.

Parameters: address The socket address to connect to.

Throws: SocketException If an error occurs. IllegalArgumentException If address type is not supported.

Since: 1.4

disconnect

public void disconnect()

This method disconnects this socket from the address/port it was connected to. If the socket was not connected in the first place, this method does nothing.

Since: 1.2

getBroadcast

public boolean getBroadcast()

Checks if SO_BROADCAST is enabled

Returns: Whether SO_BROADCAST is set

Throws: SocketException If an error occurs

Since: 1.4

getChannel

public DatagramChannel getChannel()

Returns the datagram channel assoziated with this datagram socket.

Returns: The associated DatagramChannel object or null

Since: 1.4

getInetAddress

public InetAddress getInetAddress()

This method returns the remote address to which this socket is connected. If this socket is not connected, then this method will return null.

Returns: The remote address.

Since: 1.2

getLocalAddress

public InetAddress getLocalAddress()

Returns the local address this datagram socket is bound to.

Returns: The local address is the socket is bound or null

Since: 1.1

getLocalPort

public int getLocalPort()

Returns the local port this socket is bound to.

Returns: The local port number.

getLocalSocketAddress

public SocketAddress getLocalSocketAddress()

Returns the local SocketAddress this socket is bound to.

Returns: The local SocketAddress or null if the socket is not bound.

Since: 1.4

getPort

public int getPort()

This method returns the remote port to which this socket is connected. If this socket is not connected, then this method will return -1.

Returns: The remote port.

Since: 1.2

getReceiveBufferSize

public 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.

Returns: The receive buffer size.

Throws: SocketException If an error occurs.

Since: 1.2

getRemoteSocketAddress

public SocketAddress getRemoteSocketAddress()

Returns the SocketAddress of the host this socket is conneted to or null if this socket is not connected.

Returns: The socket address of the remote host if connected or null

Since: 1.4

getReuseAddress

public boolean getReuseAddress()

Checks if SO_REUSEADDR is enabled.

Returns: True if SO_REUSEADDR is set on the socket, false otherwise.

Throws: SocketException If an error occurs.

Since: 1.4

getSendBufferSize

public int getSendBufferSize()

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

Returns: The send buffer size.

Throws: SocketException If an error occurs.

Since: 1.2

getSoTimeout

public int getSoTimeout()

Returns the value of the socket's SO_TIMEOUT setting. If this method returns 0 then SO_TIMEOUT is disabled.

Returns: The current timeout in milliseconds.

Throws: SocketException If an error occurs.

Since: 1.1

getTrafficClass

public int getTrafficClass()

Returns the current traffic class

Returns: The current traffic class.

Throws: SocketException If an error occurs

Since: 1.4

isBound

public boolean isBound()

Returns the binding state of the socket.

Returns: True if socket bound, false otherwise.

Since: 1.4

isClosed

public boolean isClosed()

Checks if the datagram socket is closed.

Returns: True if socket is closed, false otherwise.

Since: 1.4

isConnected

public boolean isConnected()

Returns the connection state of the socket.

Returns: True if socket is connected, false otherwise.

Since: 1.4

receive

public void receive(DatagramPacket p)

Reads a datagram packet from the socket. Note that this method will block until a packet is received from the network. On return, the passed in DatagramPacket is populated with the data received and all the other information about the packet.

Parameters: p A DatagramPacket for storing the data

Throws: IOException If an error occurs. SocketTimeoutException If setSoTimeout was previously called and the timeout has expired. PortUnreachableException If the socket is connected to a currently unreachable destination. Note, there is no guarantee that the exception will be thrown. IllegalBlockingModeException If this socket has an associated channel, and the channel is in non-blocking mode. SecurityException If a security manager exists and its checkAccept method doesn't allow the receive.

send

public void send(DatagramPacket p)

Sends the specified packet. The host and port to which the packet are to be sent should be set inside the packet.

Parameters: p The datagram packet to send.

Throws: IOException If an error occurs. SecurityException If a security manager exists and its checkMulticast or checkConnect method doesn't allow the send. PortUnreachableException If the socket is connected to a currently unreachable destination. Note, there is no guarantee that the exception will be thrown. IllegalBlockingModeException If this socket has an associated channel, and the channel is in non-blocking mode.

setBroadcast

public void setBroadcast(boolean enable)

Enables/Disables SO_BROADCAST

Parameters: enable True if SO_BROADCAST should be enabled, false otherwise.

Throws: SocketException If an error occurs

Since: 1.4

setDatagramSocketImplFactory

public static void setDatagramSocketImplFactory(DatagramSocketImplFactory fac)

Sets the datagram socket implementation factory for the application

Parameters: fac The factory to set

Throws: IOException If an error occurs SocketException If the factory is already defined SecurityException If a security manager exists and its checkSetFactory method doesn't allow the operation

setReceiveBufferSize

public void setReceiveBufferSize(int size)

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. IllegalArgumentException If size is 0 or negative.

Since: 1.2

setReuseAddress

public void setReuseAddress(boolean on)

Enables/Disables SO_REUSEADDR.

Parameters: on Whether or not to have SO_REUSEADDR turned on.

Throws: SocketException If an error occurs.

Since: 1.4

setSendBufferSize

public void setSendBufferSize(int size)

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

Parameters: size The new send buffer size.

Throws: SocketException If an error occurs. IllegalArgumentException If size is 0 or negative.

Since: 1.2

setSoTimeout

public void setSoTimeout(int timeout)

Sets the value of the socket's SO_TIMEOUT value. A value of 0 will disable SO_TIMEOUT. Any other value is the number of milliseconds a socket read/write will block before timing out.

Parameters: timeout The new SO_TIMEOUT value in milliseconds.

Throws: SocketException If an error occurs.

Since: 1.1

setTrafficClass

public void setTrafficClass(int tc)

Sets the traffic class value

Parameters: tc The traffic class

Throws: SocketException If an error occurs IllegalArgumentException If tc value is illegal

Since: 1.4