getLocalSocketAddress

public SocketAddress getLocalSocketAddress()

Returns the address of the endpoint this socket is bound to, or null if it is not bound yet.

Returns:

a SocketAddress representing the local endpoint of this socket, or null if it is not bound yet.

Since:

1.4

See Also:

getLocalAddress(), getLocalPort(), bind(SocketAddress)

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.

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.

Parameters:

p - the DatagramPacket to be sent.

Throws:

IOException - if an I/O error occurs.

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.

See Also:

DatagramPacket, SecurityManager.checkMulticast(InetAddress), SecurityManager.checkConnect(java.lang.String, int)

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 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.

Parameters:

p - the DatagramPacket into which to place the incoming data.

Throws:

IOException - if an I/O error occurs.

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.

See Also:

DatagramPacket, DatagramSocket

getLocalAddress

public InetAddress getLocalAddress()

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.

Returns:

the local address to which the socket is bound, or an InetAddress representing any local address if either the socket is not bound, or the security manager checkConnect method does not allow the operation

Since:

1.1

See Also:

SecurityManager.checkConnect(java.lang.String, int)

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.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.

Parameters:

timeout - the specified timeout in milliseconds.

Throws:

SocketException - if there is an error in the underlying protocol, such as an UDP error.

Since:

JDK1.1

See Also:

getSoTimeout()

getSoTimeout

public int getSoTimeout()
                 throws SocketException

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

Returns:

the setting for SO_TIMEOUT

Throws:

SocketException - if there is an error in the underlying protocol, such as an UDP error.

Since:

JDK1.1

See Also:

setSoTimeout(int)

setSendBufferSize

public void setSendBufferSize(int size)
                       throws SocketException

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() 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.

Parameters:

size - the size to which to set the send buffer size. This value must be greater than 0.

Throws:

SocketException - if there is an error in the underlying protocol, such as an UDP error.

IllegalArgumentException - if the value is 0 or is negative.

See Also:

getSendBufferSize()

getSendBufferSize

public int getSendBufferSize()
                      throws SocketException

Get value of the SO_SNDBUF option for this DatagramSocket, that is the buffer size used by the platform for output on this DatagramSocket.

Returns:

the value of the SO_SNDBUF option for this DatagramSocket

Throws:

SocketException - if there is an error in the underlying protocol, such as an UDP error.

See Also:

setSendBufferSize(int)

setReceiveBufferSize

public void setReceiveBufferSize(int size)
                          throws SocketException

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().

Note: It is implementation specific if a packet larger than SO_RCVBUF can be received.

Parameters:

size - the size to which to set the receive buffer size. This value must be greater than 0.

Throws:

SocketException - if there is an error in the underlying protocol, such as an UDP error.

IllegalArgumentException - if the value is 0 or is negative.

See Also:

getReceiveBufferSize()

getReceiveBufferSize

public int getReceiveBufferSize()
                         throws SocketException

Get value of the SO_RCVBUF option for this DatagramSocket, that is the buffer size used by the platform for input on this DatagramSocket.

Returns:

the value of the SO_RCVBUF option for this DatagramSocket

Throws:

SocketException - if there is an error in the underlying protocol, such as an UDP error.

See Also:

setReceiveBufferSize(int)

setReuseAddress

public void setReuseAddress(boolean on)
                     throws SocketException

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 #java.net.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).

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.

Parameters:

on - whether to enable or disable the

Throws:

SocketException - if an error occurs enabling or disabling the SO_RESUEADDR socket option, or the socket is closed.

Since:

1.4

See Also:

getReuseAddress(), bind(SocketAddress), isBound(), isClosed()

getReuseAddress

public boolean getReuseAddress()
                        throws SocketException

Tests if SO_REUSEADDR is enabled.

Returns:

a boolean indicating whether or not SO_REUSEADDR is enabled.

Throws:

SocketException - if there is an error in the underlying protocol, such as an UDP error.

Since:

1.4

See Also:

setReuseAddress(boolean)

setBroadcast

public void setBroadcast(boolean on)
                  throws SocketException

Enable/disable SO_BROADCAST.

Parameters:

on - whether or not to have broadcast turned on.

Throws:

SocketException - if there is an error in the underlying protocol, such as an UDP error.

Since:

1.4

See Also:

getBroadcast()

getBroadcast

public boolean getBroadcast()
                     throws SocketException

Tests if SO_BROADCAST is enabled.

Returns:

a boolean indicating whether or not SO_BROADCAST is enabled.

Throws:

SocketException - if there is an error in the underlying protocol, such as an UDP error.

Since:

1.4

See Also:

setBroadcast(boolean)

setTrafficClass

public void setTrafficClass(int tc)
                     throws SocketException

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)

The last low order bit is always ignored as this corresponds to the MBZ (must be zero) bit.

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.

Parameters:

tc - an int value for the bitset.

Throws:

SocketException - if there is an error setting the traffic class or type-of-service

Since:

1.4

See Also:

getTrafficClass()

getTrafficClass

public int getTrafficClass()
                    throws SocketException

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() this method may return a different value than was previously set using the #setTrafficClass() method on this DatagramSocket.

Returns:

the traffic class or type-of-service already set

Throws:

SocketException - if there is an error obtaining the traffic class or type-of-service value.

Since:

1.4

See Also:

setTrafficClass(int)

close

public void close()

Closes this datagram socket.

Any thread currently blocked in {#link receive} upon this socket will throw a SocketException.

If this socket has an associated channel then the channel is closed as well.

isClosed

public boolean isClosed()

Returns wether the socket is closed or not.

Returns:

true if the socket has been closed

Since:

1.4

getChannel

public DatagramChannel getChannel()

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 datagram channel associated with this datagram socket, or null if this socket was not created for a channel

Since:

1.4

setDatagramSocketImplFactory

public static void setDatagramSocketImplFactory(DatagramSocketImplFactory fac)
                                         throws IOException

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.

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.

Parameters:

fac - the desired factory.

Throws:

IOException - if an I/O error occurs when setting the datagram socket factory.

SocketException - if the factory is already defined.

SecurityException - if a security manager exists and its checkSetFactory method doesn't allow the operation.

See Also:

DatagramSocketImplFactory.createDatagramSocketImpl(), SecurityManager.checkSetFactory()