Closeable
, AutoCloseable
, Channel
, InterruptibleChannel
DatagramChannel
, Pipe.SinkChannel
, Pipe.SourceChannel
, SctpChannel
, SctpMultiChannel
, SctpServerChannel
, ServerSocketChannel
, SocketChannel
public abstract class AbstractSelectableChannel extends SelectableChannel
This class defines methods that handle the mechanics of channel registration, deregistration, and closing. It maintains the current blocking mode of this channel as well as its current set of selection keys. It performs all of the synchronization required to implement the SelectableChannel
specification. Implementations of the protected abstract methods defined in this class need not synchronize against other threads that might be engaged in the same operations.
Modifier | Constructor | Description |
---|---|---|
protected |
Initializes a new instance of this class. |
Modifier and Type | Method | Description |
---|---|---|
final Object |
blockingLock() |
Retrieves the object upon which the configureBlocking and register methods synchronize. |
final SelectableChannel |
configureBlocking |
Adjusts this channel's blocking mode. |
protected final void |
implCloseChannel() |
Closes this channel. |
protected abstract void |
implCloseSelectableChannel() |
Closes this selectable channel. |
protected abstract void |
implConfigureBlocking |
Adjusts this channel's blocking mode. |
final boolean |
isBlocking() |
Tells whether or not every I/O operation on this channel will block until it completes. |
final boolean |
isRegistered() |
Tells whether or not this channel is currently registered with any selectors. |
final SelectionKey |
keyFor |
Retrieves the key representing the channel's registration with the given selector. |
final SelectorProvider |
provider() |
Returns the provider that created this channel. |
final SelectionKey |
register |
Registers this channel with the given selector, returning a selection key. |
register, validOps
begin, close, end, isOpen
protected AbstractSelectableChannel(SelectorProvider provider)
provider
- The provider that created this channelpublic final SelectorProvider provider()
provider
in class SelectableChannel
public final boolean isRegistered()
SelectableChannel
Due to the inherent delay between key cancellation and channel deregistration, a channel may remain registered for some time after all of its keys have been cancelled. A channel may also remain registered for some time after it is closed.
isRegistered
in class SelectableChannel
true
if, and only if, this channel is registeredpublic final SelectionKey keyFor(Selector sel)
SelectableChannel
keyFor
in class SelectableChannel
sel
- The selectornull
if this channel is not currently registered with that selectorpublic final SelectionKey register(Selector sel, int ops, Object att) throws ClosedChannelException
This method first verifies that this channel is open and that the given initial interest set is valid.
If this channel is already registered with the given selector then the selection key representing that registration is returned after setting its interest set to the given value.
Otherwise this channel has not yet been registered with the given selector, so the register
method of the selector is invoked while holding the appropriate locks. The resulting key is added to this channel's key set before being returned.
register
in class SelectableChannel
sel
- The selector with which this channel is to be registeredops
- The interest set for the resulting keyatt
- The attachment for the resulting key; may be null
ClosedSelectorException
- If the selector is closedIllegalBlockingModeException
- If this channel is in blocking modeIllegalSelectorException
- If this channel was not created by the same provider as the given selectorCancelledKeyException
- If this channel is currently registered with the given selector but the corresponding key has already been cancelledIllegalArgumentException
- If a bit in the ops
set does not correspond to an operation that is supported by this channel, that is, if set & ~validOps() != 0
ClosedChannelException
- If this channel is closedprotected final void implCloseChannel() throws IOException
This method, which is specified in the AbstractInterruptibleChannel
class and is invoked by the close
method, in turn invokes the implCloseSelectableChannel
method in order to perform the actual work of closing this channel. It then cancels all of this channel's keys.
implCloseChannel
in class AbstractInterruptibleChannel
IOException
- If an I/O error occurs while closing the channelprotected abstract void implCloseSelectableChannel() throws IOException
This method is invoked by the close
method in order to perform the actual work of closing the channel. This method is only invoked if the channel has not yet been closed, and it is never invoked more than once.
An implementation of this method must arrange for any other thread that is blocked in an I/O operation upon this channel to return immediately, either by throwing an exception or by returning normally.
IOException
- If an I/O error occurspublic final boolean isBlocking()
SelectableChannel
If this channel is closed then the value returned by this method is not specified.
isBlocking
in class SelectableChannel
true
if, and only if, this channel is in blocking modepublic final Object blockingLock()
SelectableChannel
configureBlocking
and register
methods synchronize. This is often useful in the implementation of adaptors that require a specific blocking mode to be maintained for a short period of time.blockingLock
in class SelectableChannel
public final SelectableChannel configureBlocking(boolean block) throws IOException
If the given blocking mode is different from the current blocking mode then this method invokes the implConfigureBlocking
method, while holding the appropriate locks, in order to change the mode.
configureBlocking
in class SelectableChannel
block
- If true
then this channel will be placed in blocking mode; if false
then it will be placed non-blocking modeClosedChannelException
- If this channel is closedIOException
- If an I/O error occursprotected abstract void implConfigureBlocking(boolean block) throws IOException
This method is invoked by the configureBlocking
method in order to perform the actual work of changing the blocking mode. This method is only invoked if the new mode is different from the current mode.
block
- If true
then this channel will be placed in blocking mode; if false
then it will be placed non-blocking modeIOException
- If an I/O error occurs
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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/nio/channels/spi/AbstractSelectableChannel.html