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java.net

Class DatagramSocket

Known Direct Subclasses:
MulticastSocket
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.

Constructor Summary

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(DatagramSocketImpl impl)
Creates a DatagramSocket from a specified DatagramSocketImpl instance
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

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

DatagramSocket

public DatagramSocket()
            throws SocketException
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)
            throws SocketException
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)
            throws SocketException
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

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(SocketAddress address)
            throws SocketException
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 Details

bind

public void bind(SocketAddress address)
            throws SocketException
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)
            throws SocketException
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()
            throws SocketException
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()
            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.
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()
            throws SocketException
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()
            throws SocketException
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()
            throws SocketException
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()
            throws SocketException
Returns the current traffic class
Returns:
The current traffic class.
Throws:
SocketException - If an error occurs
Since:
1.4
See Also:
DatagramSocket.setTrafficClass(int tc)

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)
            throws IOException
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.
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)
            throws IOException
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.
IllegalBlockingModeException - If this socket has an associated channel, and the channel is in non-blocking mode.

setBroadcast

public void setBroadcast(boolean enable)
            throws SocketException
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)
            throws IOException
Sets the datagram socket implementation factory for the application
Parameters:
fac - The factory to set
Throws:
IOException - If an error occurs
SecurityException - If a security manager exists and its checkSetFactory method doesn't allow the operation

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.
IllegalArgumentException - If size is 0 or negative.
Since:
1.2

setReuseAddress

public void setReuseAddress(boolean on)
            throws SocketException
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)
            throws SocketException
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)
            throws SocketException
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)
            throws SocketException
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
See Also:
getTrafficClass()
DatagramSocket.java -- A class to model UDP sockets Copyright (C) 1998, 1999, 2000, 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.

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