java.lang.Object | |
↳ | java.net.DatagramSocket |
Known Direct Subclasses |
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 are always enabled on a DatagramSocket. In order to receive broadcast packets a DatagramSocket should be bound to the wildcard address. In some implementations, broadcast packets may also be received when a DatagramSocket is bound to a more specific address.
Example:
DatagramSocket s = new DatagramSocket(null);
s.bind(new InetSocketAddress(8888));
Which is equivalent to:
DatagramSocket s = new DatagramSocket(8888);
Both cases will create a DatagramSocket able to receive broadcasts on
UDP port 8888.
Public Constructors | |||||||||||
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Constructs a datagram socket and binds it to any available port
on the local host machine.
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Creates a datagram socket, bound to the specified local
socket address.
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Constructs a datagram socket and binds it to the specified port
on the local host machine.
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Creates a datagram socket, bound to the specified local
address.
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Protected Constructors | |||||||||||
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Creates an unbound datagram socket with the specified
DatagramSocketImpl.
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Public Methods | |||||||||||
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Binds this DatagramSocket to a specific address & port.
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Closes this datagram socket.
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Connects this socket to a remote socket address (IP address + port number).
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Connects the socket to a remote address for this socket.
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Disconnects the socket.
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Tests if SO_BROADCAST is enabled.
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Returns the unique
DatagramChannel object
associated with this datagram socket, if any. | |||||||||||
Returns the address to which this socket is connected.
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Gets the local address to which the socket is bound.
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Returns the port number on the local host to which this socket
is bound.
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Returns the address of the endpoint this socket is bound to, or
null if it is not bound yet. | |||||||||||
Returns the port number to which this socket is connected.
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Get value of the SO_RCVBUF option for this DatagramSocket, that is the
buffer size used by the platform for input on this DatagramSocket.
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Returns the address of the endpoint this socket is connected to, or
null if it is unconnected. | |||||||||||
Tests if SO_REUSEADDR is enabled.
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Get value of the SO_SNDBUF option for this DatagramSocket, that is the
buffer size used by the platform for output on this DatagramSocket.
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Retrieve setting for SO_TIMEOUT.
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Gets traffic class or type-of-service in the IP datagram
header for packets sent from this DatagramSocket.
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Returns the binding state of the socket.
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Returns whether the socket is closed or not.
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Returns the connection state of the socket.
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Receives a datagram packet from this socket.
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Sends a datagram packet from this socket.
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Enable/disable SO_BROADCAST.
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Sets the datagram socket implementation factory for the
application.
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Sets the SO_RCVBUF option to the specified value for this
DatagramSocket.
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Enable/disable the SO_REUSEADDR socket option.
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Sets the SO_SNDBUF option to the specified value for this
DatagramSocket.
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Enable/disable SO_TIMEOUT with the specified timeout, in
milliseconds.
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Sets traffic class or type-of-service octet in the IP
datagram header for datagrams sent from this DatagramSocket.
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[Expand]
Inherited Methods | |||||||||||
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From class
java.lang.Object
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Constructs a datagram socket and binds it to any available port
on the local host machine. The socket will be bound to the
wildcard
address,
an IP address chosen by the kernel.
If there is a security manager,
its checkListen
method is first called
with 0 as its argument to ensure the operation is allowed.
This could result in a SecurityException.
SocketException | if the socket could not be opened, or the socket could not bind to the specified local port. |
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SecurityException | if a security manager exists and its
checkListen method doesn't allow the operation. |
Creates a datagram socket, bound to the specified local socket address.
If, if the address is null
, creates an unbound socket.
If there is a security manager,
its checkListen
method is first called
with the port from the socket address
as its argument to ensure the operation is allowed.
This could result in a SecurityException.
bindaddr | local socket address to bind, or null
for an unbound socket. |
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SocketException | if the socket could not be opened, or the socket could not bind to the specified local port. |
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SecurityException | if a security manager exists and its
checkListen method doesn't allow the operation. |
Constructs a datagram socket and binds it to the specified port
on the local host machine. The socket will be bound to the
wildcard
address,
an IP address chosen by the kernel.
If there is a security manager,
its checkListen
method is first called
with the port
argument
as its argument to ensure the operation is allowed.
This could result in a SecurityException.
port | port to use. |
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SocketException | if the socket could not be opened, or the socket could not bind to the specified local port. |
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SecurityException | if a security manager exists and its
checkListen method doesn't allow the operation. |
Creates a datagram socket, bound to the specified local
address. The local port must be between 0 and 65535 inclusive.
If the IP address is 0.0.0.0, the socket will be bound to the
wildcard
address,
an IP address chosen by the kernel.
If there is a security manager,
its checkListen
method is first called
with the port
argument
as its argument to ensure the operation is allowed.
This could result in a SecurityException.
port | local port to use |
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laddr | local address to bind |
SocketException | if the socket could not be opened, or the socket could not bind to the specified local port. |
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SecurityException | if a security manager exists and its
checkListen method doesn't allow the operation. |
Creates an unbound datagram socket with the specified DatagramSocketImpl.
impl | an instance of a DatagramSocketImpl the subclass wishes to use on the DatagramSocket. |
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Binds this DatagramSocket to a specific address & port.
If the address is null
, then the system will pick up
an ephemeral port and a valid local address to bind the socket.
addr | The address & port to bind to. |
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SocketException | if any error happens during the bind, or if the socket is already bound. |
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SecurityException | if a security manager exists and its
checkListen method doesn't allow the operation. |
IllegalArgumentException | if addr is a SocketAddress subclass not supported by this socket. |
Closes this datagram socket.
Any thread currently blocked in receive(DatagramPacket)
upon this socket
will throw a SocketException
.
If this socket has an associated channel then the channel is closed as well.
Connects this socket to a remote socket address (IP address + port number).
addr | The remote address. |
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SocketException | if the connect fails |
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IllegalArgumentException | if addr is null or addr is a SocketAddress subclass not supported by this socket |
Connects the socket to a remote address for this socket. When a socket is connected to a remote address, packets may only be sent to or received from that address. By default a datagram socket is not connected.
If the remote destination to which the socket is connected does not exist, or is otherwise unreachable, and if an ICMP destination unreachable packet has been received for that address, then a subsequent call to send or receive may throw a PortUnreachableException. Note, there is no guarantee that the exception will be thrown.
A caller's permission to send and receive datagrams to a given host and port are checked at connect time. When a socket is connected, receive and send will not perform any security checks on incoming and outgoing packets, other than matching the packet's and the socket's address and port. On a send operation, if the packet's address is set and the packet's address and the socket's address do not match, an IllegalArgumentException will be thrown. A socket connected to a multicast address may only be used to send packets.
address | the remote address for the socket |
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port | the remote port for the socket. |
IllegalArgumentException | if the address is null, or the port is out of range. |
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SecurityException | if the caller is not allowed to send datagrams to and receive datagrams from the address and port. |
Disconnects the socket. This does nothing if the socket is not connected.
Tests if SO_BROADCAST is enabled.
boolean
indicating whether or not SO_BROADCAST is enabled.SocketException | if there is an error in the underlying protocol, such as an UDP error. |
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Returns the unique DatagramChannel
object
associated with this datagram socket, if any.
A datagram socket will have a channel if, and only if, the channel
itself was created via the DatagramChannel.open
method.
Returns the address to which this socket is connected. Returns
null
if the socket is not connected.
Gets the local address to which the socket is bound.
If there is a security manager, its
checkConnect
method is first called
with the host address and -1
as its arguments to see if the operation is allowed.
InetAddress
representing any local
address if either the socket is not bound, or
the security manager checkConnect
method does not allow the operationReturns the port number on the local host to which this socket is bound.
Returns the address of the endpoint this socket is bound to, or
null
if it is not bound yet.
SocketAddress
representing the local endpoint of this
socket, or null
if it is not bound yet.Returns the port number to which this socket is connected.
Returns -1
if the socket is not connected.
Get value of the SO_RCVBUF option for this DatagramSocket, that is the buffer size used by the platform for input on this DatagramSocket.
SocketException | if there is an error in the underlying protocol, such as an UDP error. |
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Returns the address of the endpoint this socket is connected to, or
null
if it is unconnected.
SocketAddress
representing the remote
endpoint of this socket, or null
if it is
not connected yet.Tests if SO_REUSEADDR is enabled.
boolean
indicating whether or not SO_REUSEADDR is enabled.SocketException | if there is an error in the underlying protocol, such as an UDP error. |
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Get value of the SO_SNDBUF option for this DatagramSocket, that is the buffer size used by the platform for output on this DatagramSocket.
SocketException | if there is an error in the underlying protocol, such as an UDP error. |
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Retrieve setting for SO_TIMEOUT. 0 returns implies that the option is disabled (i.e., timeout of infinity).
SocketException | if there is an error in the underlying protocol, such as an UDP error. |
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Gets traffic class or type-of-service in the IP datagram header for packets sent from this DatagramSocket.
As the underlying network implementation may ignore the
traffic class or type-of-service set using setTrafficClass(int)
this method may return a different value than was previously
set using the setTrafficClass(int)
method on this
DatagramSocket.
SocketException | if there is an error obtaining the traffic class or type-of-service value. |
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Returns the binding state of the socket.
Returns whether the socket is closed or not.
Returns the connection state of the socket.
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.
If there is a security manager, a packet cannot be received if the
security manager's checkAccept
method
does not allow it.
p | the DatagramPacket into which to place
the incoming data. |
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IOException | if an I/O error occurs. |
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SocketTimeoutException | if setSoTimeout was previously called and the timeout has expired. |
PortUnreachableException | may be thrown 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. |
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.
If there is a security manager, and the socket is not currently
connected to a remote address, this method first performs some
security checks. First, if p.getAddress().isMulticastAddress()
is true, this method calls the
security manager's checkMulticast
method
with p.getAddress()
as its argument.
If the evaluation of that expression is false,
this method instead calls the security manager's
checkConnect
method with arguments
p.getAddress().getHostAddress()
and
p.getPort()
. Each call to a security manager method
could result in a SecurityException if the operation is not allowed.
p | the DatagramPacket to be sent. |
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IOException | if an I/O error occurs. |
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SecurityException | if a security manager exists and its
checkMulticast or checkConnect
method doesn't allow the send. |
PortUnreachableException | may be thrown 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. |
Enable/disable SO_BROADCAST.
on | whether or not to have broadcast turned on. |
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SocketException | if there is an error in the underlying protocol, such as an UDP error. |
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Sets the datagram socket implementation factory for the application. The factory can be specified only once.
When an application creates a new datagram socket, the socket
implementation factory's createDatagramSocketImpl
method is
called to create the actual datagram socket implementation.
Passing null
to the method is a no-op unless the factory
was already set.
If there is a security manager, this method first calls
the security manager's checkSetFactory
method
to ensure the operation is allowed.
This could result in a SecurityException.
fac | the desired factory. |
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IOException | if an I/O error occurs when setting the datagram socket factory. |
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SocketException | if the factory is already defined. |
SecurityException | if a security manager exists and its
checkSetFactory method doesn't allow the
operation. |
Sets the SO_RCVBUF option to the specified value for this DatagramSocket. The SO_RCVBUF option is used by the the network implementation as a hint to size the underlying network I/O buffers. The SO_RCVBUF setting may also be used by the network implementation to determine the maximum size of the packet that can be received on this socket.
Because SO_RCVBUF is a hint, applications that want to
verify what size the buffers were set to should call
getReceiveBufferSize()
.
Increasing SO_RCVBUF may allow the network implementation
to buffer multiple packets when packets arrive faster than
are being received using receive(DatagramPacket)
.
Note: It is implementation specific if a packet larger than SO_RCVBUF can be received.
size | the size to which to set the receive buffer size. This value must be greater than 0. |
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SocketException | if there is an error in the underlying protocol, such as an UDP error. |
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IllegalArgumentException | if the value is 0 or is negative. |
Enable/disable the SO_REUSEADDR socket option.
For UDP sockets it may be necessary to bind more than one
socket to the same socket address. This is typically for the
purpose of receiving multicast packets
(See MulticastSocket
). The
SO_REUSEADDR socket option allows multiple
sockets to be bound to the same socket address if the
SO_REUSEADDR socket option is enabled prior
to binding the socket using bind(SocketAddress)
.
Note: This functionality is not supported by all existing platforms,
so it is implementation specific whether this option will be ignored
or not. However, if it is not supported then
getReuseAddress()
will always return false
.
When a DatagramSocket is created the initial setting of SO_REUSEADDR is disabled.
The behaviour when SO_REUSEADDR is enabled or
disabled after a socket is bound (See isBound()
)
is not defined.
on | whether to enable or disable the |
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SocketException | if an error occurs enabling or disabling the SO_RESUEADDR socket option, or the socket is closed. |
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Sets the SO_SNDBUF option to the specified value for this DatagramSocket. The SO_SNDBUF option is used by the network implementation as a hint to size the underlying network I/O buffers. The SO_SNDBUF setting may also be used by the network implementation to determine the maximum size of the packet that can be sent on this socket.
As SO_SNDBUF is a hint, applications that want to verify
what size the buffer is should call getSendBufferSize()
.
Increasing the buffer size may allow multiple outgoing packets to be queued by the network implementation when the send rate is high.
Note: If send(DatagramPacket)
is used to send a
DatagramPacket
that is larger than the setting
of SO_SNDBUF then it is implementation specific if the
packet is sent or discarded.
size | the size to which to set the send buffer size. This value must be greater than 0. |
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SocketException | if there is an error in the underlying protocol, such as an UDP error. |
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IllegalArgumentException | if the value is 0 or is negative. |
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.net.SocketTimeoutException is raised, though the DatagramSocket 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.
timeout | the specified timeout in milliseconds. |
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SocketException | if there is an error in the underlying protocol, such as an UDP error. |
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Sets traffic class or type-of-service octet in the IP datagram header for datagrams sent from this DatagramSocket. As the underlying network implementation may ignore this value applications should consider it a hint.
The tc must be in the range 0 <= tc <=
255
or an IllegalArgumentException will be thrown.
Notes:
for Internet Protocol v4 the value consists of an octet with precedence and TOS fields as detailed in RFC 1349. The TOS field is bitset created by bitwise-or'ing values such the following :-
IPTOS_LOWCOST (0x02)
IPTOS_RELIABILITY (0x04)
IPTOS_THROUGHPUT (0x08)
IPTOS_LOWDELAY (0x10)
Setting bits in the precedence field may result in a SocketException indicating that the operation is not permitted.
for Internet Protocol v6 tc
is the value that
would be placed into the sin6_flowinfo field of the IP header.
tc | an int value for the bitset. |
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SocketException | if there is an error setting the traffic class or type-of-service |
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