java.lang.Object | ||||
↳ | java.nio.channels.spi.AbstractInterruptibleChannel | |||
↳ | java.nio.channels.SelectableChannel | |||
↳ | java.nio.channels.spi.AbstractSelectableChannel | |||
↳ | java.nio.channels.DatagramChannel |
A selectable channel for datagram-oriented sockets.
Datagram channels are not a complete abstraction of network datagram
sockets. Binding and the manipulation of socket options must be done
through an associated DatagramSocket
object obtained by
invoking the socket
method. It is not possible to create
a channel for an arbitrary, pre-existing datagram socket, nor is it possible
to specify the DatagramSocketImpl
object to be used by a
datagram socket associated with a datagram channel.
A datagram channel is created by invoking the open
method
of this class. A newly-created datagram channel is open but not connected.
A datagram channel need not be connected in order for the send
and receive
methods to be used. A datagram channel may be
connected, by invoking its connect
method, in order to
avoid the overhead of the security checks are otherwise performed as part of
every send and receive operation. A datagram channel must be connected in
order to use the read
and write
methods, since those methods do not
accept or return socket addresses.
Once connected, a datagram channel remains connected until it is
disconnected or closed. Whether or not a datagram channel is connected may
be determined by invoking its isConnected
method.
Datagram channels are safe for use by multiple concurrent threads. They support concurrent reading and writing, though at most one thread may be reading and at most one thread may be writing at any given time.
Protected Constructors | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Initializes a new instance of this class.
|
Public Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Connects this channel's socket.
| |||||||||||
Disconnects this channel's socket.
| |||||||||||
Tells whether or not this channel's socket is connected.
| |||||||||||
Opens a datagram channel.
| |||||||||||
Reads a datagram from this channel.
| |||||||||||
Reads a datagram from this channel.
| |||||||||||
Reads a datagram from this channel.
| |||||||||||
Receives a datagram via this channel.
| |||||||||||
Sends a datagram via this channel.
| |||||||||||
Retrieves a datagram socket associated with this channel.
| |||||||||||
Returns an operation set identifying this channel's supported
operations.
| |||||||||||
Writes a datagram to this channel.
| |||||||||||
Writes a datagram to this channel.
| |||||||||||
Writes a datagram to this channel.
|
[Expand]
Inherited Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
From class
java.nio.channels.spi.AbstractSelectableChannel
| |||||||||||
From class
java.nio.channels.SelectableChannel
| |||||||||||
From class
java.nio.channels.spi.AbstractInterruptibleChannel
| |||||||||||
From class
java.lang.Object
| |||||||||||
From interface
java.io.Closeable
| |||||||||||
From interface
java.nio.channels.Channel
| |||||||||||
From interface
java.nio.channels.GatheringByteChannel
| |||||||||||
From interface
java.nio.channels.InterruptibleChannel
| |||||||||||
From interface
java.nio.channels.ReadableByteChannel
| |||||||||||
From interface
java.nio.channels.ScatteringByteChannel
| |||||||||||
From interface
java.nio.channels.WritableByteChannel
|
Connects this channel's socket.
The channel's socket is configured so that it only receives datagrams from, and sends datagrams to, the given remote peer address. Once connected, datagrams may not be received from or sent to any other address. A datagram socket remains connected until it is explicitly disconnected or until it is closed.
This method performs exactly the same security checks as the connect
method of the DatagramSocket
class. That is, if a security manager has been
installed then this method verifies that its checkAccept
and checkConnect
methods permit
datagrams to be received from and sent to, respectively, the given
remote address.
This method may be invoked at any time. It will not have any effect on read or write operations that are already in progress at the moment that it is invoked.
remote | The remote address to which this channel is to be connected |
---|
If this channel is closed | |
If another thread closes this channel while the connect operation is in progress | |
If another thread interrupts the current thread while the connect operation is in progress, thereby closing the channel and setting the current thread's interrupt status | |
SecurityException | If a security manager has been installed and it does not permit access to the given remote address |
IOException | If some other I/O error occurs |
Disconnects this channel's socket.
The channel's socket is configured so that it can receive datagrams from, and sends datagrams to, any remote address so long as the security manager, if installed, permits it.
This method may be invoked at any time. It will not have any effect on read or write operations that are already in progress at the moment that it is invoked.
If this channel's socket is not connected, or if the channel is closed, then invoking this method has no effect.
IOException | If some other I/O error occurs |
---|
Tells whether or not this channel's socket is connected.
Opens a datagram channel.
The new channel is created by invoking the openDatagramChannel
method of the system-wide default SelectorProvider
object. The channel will not be
connected.
IOException | If an I/O error occurs |
---|
Reads a datagram from this channel.
This method may only be invoked if this channel's socket is
connected, and it only accepts datagrams from the socket's peer. If
there are more bytes in the datagram than remain in the given buffer
then the remainder of the datagram is silently discarded. Otherwise
this method behaves exactly as specified in the ReadableByteChannel
interface.
dst | The buffer into which bytes are to be transferred |
---|
If this channel's socket is not connected | |
IOException |
Reads a datagram from this channel.
This method may only be invoked if this channel's socket is
connected, and it only accepts datagrams from the socket's peer. If
there are more bytes in the datagram than remain in the given buffers
then the remainder of the datagram is silently discarded. Otherwise
this method behaves exactly as specified in the ScatteringByteChannel
interface.
dsts | The buffers into which bytes are to be transferred |
---|---|
offset | The offset within the buffer array of the first buffer into which bytes are to be transferred; must be non-negative and no larger than dsts.length |
length | The maximum number of buffers to be accessed; must be non-negative and no larger than dsts.length - offset |
If this channel's socket is not connected | |
IOException |
Reads a datagram from this channel.
This method may only be invoked if this channel's socket is
connected, and it only accepts datagrams from the socket's peer. If
there are more bytes in the datagram than remain in the given buffers
then the remainder of the datagram is silently discarded. Otherwise
this method behaves exactly as specified in the ScatteringByteChannel
interface.
dsts | The buffers into which bytes are to be transferred |
---|
If this channel's socket is not connected | |
IOException |
Receives a datagram via this channel.
If a datagram is immediately available, or if this channel is in blocking mode and one eventually becomes available, then the datagram is copied into the given byte buffer and its source address is returned. If this channel is in non-blocking mode and a datagram is not immediately available then this method immediately returns null.
The datagram is transferred into the given byte buffer starting at
its current position, as if by a regular read
operation. If there
are fewer bytes remaining in the buffer than are required to hold the
datagram then the remainder of the datagram is silently discarded.
This method performs exactly the same security checks as the receive
method of the DatagramSocket
class. That is, if the socket is not connected
to a specific remote address and a security manager has been installed
then for each datagram received this method verifies that the source's
address and port number are permitted by the security manager's checkAccept
method. The overhead
of this security check can be avoided by first connecting the socket via
the connect
method.
This method may be invoked at any time. If another thread has already initiated a read operation upon this channel, however, then an invocation of this method will block until the first operation is complete.
dst | The buffer into which the datagram is to be transferred |
---|
If this channel is closed | |
If another thread closes this channel while the read operation is in progress | |
If another thread interrupts the current thread while the read operation is in progress, thereby closing the channel and setting the current thread's interrupt status | |
SecurityException | If a security manager has been installed and it does not permit datagrams to be accepted from the datagram's sender |
IOException | If some other I/O error occurs |
Sends a datagram via this channel.
If this channel is in non-blocking mode and there is sufficient room in the underlying output buffer, or if this channel is in blocking mode and sufficient room becomes available, then the remaining bytes in the given buffer are transmitted as a single datagram to the given target address.
The datagram is transferred from the byte buffer as if by a regular
write
operation.
This method performs exactly the same security checks as the send
method of the DatagramSocket
class. That is, if the socket is not connected
to a specific remote address and a security manager has been installed
then for each datagram sent this method verifies that the target address
and port number are permitted by the security manager's checkConnect
method. The
overhead of this security check can be avoided by first connecting the
socket via the connect
method.
This method may be invoked at any time. If another thread has already initiated a write operation upon this channel, however, then an invocation of this method will block until the first operation is complete.
src | The buffer containing the datagram to be sent |
---|---|
target | The address to which the datagram is to be sent |
If this channel is closed | |
If another thread closes this channel while the read operation is in progress | |
If another thread interrupts the current thread while the read operation is in progress, thereby closing the channel and setting the current thread's interrupt status | |
SecurityException | If a security manager has been installed and it does not permit datagrams to be sent to the given address |
IOException | If some other I/O error occurs |
Retrieves a datagram socket associated with this channel.
The returned object will not declare any public methods that are not
declared in the DatagramSocket
class.
Writes a datagram to this channel.
This method may only be invoked if this channel's socket is
connected, in which case it sends datagrams directly to the socket's
peer. Otherwise it behaves exactly as specified in the GatheringByteChannel
interface.
srcs | The buffers from which bytes are to be retrieved |
---|
If this channel's socket is not connected | |
IOException |
Writes a datagram to this channel.
This method may only be invoked if this channel's socket is
connected, in which case it sends datagrams directly to the socket's
peer. Otherwise it behaves exactly as specified in the GatheringByteChannel
interface.
srcs | The buffers from which bytes are to be retrieved |
---|---|
offset | The offset within the buffer array of the first buffer from which bytes are to be retrieved; must be non-negative and no larger than srcs.length |
length | The maximum number of buffers to be accessed; must be non-negative and no larger than srcs.length - offset |
If this channel's socket is not connected | |
IOException |
Writes a datagram to this channel.
This method may only be invoked if this channel's socket is
connected, in which case it sends datagrams directly to the socket's
peer. Otherwise it behaves exactly as specified in the WritableByteChannel
interface.
src | The buffer from which bytes are to be retrieved |
---|
If this channel's socket is not connected | |
IOException |