- All Implemented Interfaces:
Closeable
,AutoCloseable
,Channel
,InterruptibleChannel
- Direct Known Subclasses:
DatagramChannel
,Pipe.SinkChannel
,Pipe.SourceChannel
,ServerSocketChannel
,SocketChannel
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.
- Since:
- 1.4
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Constructor Summary
ModifierConstructorDescriptionprotected
AbstractSelectableChannel
(SelectorProvider provider) Initializes a new instance of this class. -
Method Summary
Modifier and TypeMethodDescriptionfinal Object
Retrieves the object upon which theconfigureBlocking
andregister
methods synchronize.final SelectableChannel
configureBlocking
(boolean block) Adjusts this channel's blocking mode.protected final void
Closes this channel.protected abstract void
Closes this selectable channel.protected abstract void
implConfigureBlocking
(boolean block) Adjusts this channel's blocking mode.final boolean
Tells whether or not every I/O operation on this channel will block until it completes.final boolean
Tells whether or not this channel is currently registered with any selectors.final SelectionKey
Retrieves the key representing the channel's registration with the given selector.final SelectorProvider
provider()
Returns the provider that created this channel.final SelectionKey
Registers this channel with the given selector, returning a selection key.Methods declared in class java.nio.channels.SelectableChannel
register, validOps
Methods declared in class java.nio.channels.spi.AbstractInterruptibleChannel
begin, close, end, isOpen
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Constructor Details
-
AbstractSelectableChannel
Initializes a new instance of this class.- Parameters:
provider
- The provider that created this channel
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-
Method Details
-
provider
Returns the provider that created this channel.- Specified by:
provider
in classSelectableChannel
- Returns:
- The provider that created this channel
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isRegistered
public final boolean isRegistered()Description copied from class:SelectableChannel
Tells whether or not this channel is currently registered with any selectors. A newly-created channel is not registered.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.
- Specified by:
isRegistered
in classSelectableChannel
- Returns:
true
if, and only if, this channel is registered
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keyFor
Description copied from class:SelectableChannel
Retrieves the key representing the channel's registration with the given selector.- Specified by:
keyFor
in classSelectableChannel
- Parameters:
sel
- The selector- Returns:
- The key returned when this channel was last registered with the
given selector, or
null
if this channel is not currently registered with that selector
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register
Registers this channel with the given selector, returning a selection key.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.- Specified by:
register
in classSelectableChannel
- Parameters:
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 benull
- Returns:
- A key representing the registration of this channel with the given selector
- Throws:
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 theops
set does not correspond to an operation that is supported by this channel, that is, ifset & ~validOps() != 0
ClosedChannelException
- If this channel is closed
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implCloseChannel
Closes this channel.This method, which is specified in the
AbstractInterruptibleChannel
class and is invoked by theclose
method, in turn invokes theimplCloseSelectableChannel
method in order to perform the actual work of closing this channel. It then cancels all of this channel's keys.- Specified by:
implCloseChannel
in classAbstractInterruptibleChannel
- Throws:
IOException
- If an I/O error occurs while closing the channel
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implCloseSelectableChannel
Closes this selectable channel.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.
- Throws:
IOException
- If an I/O error occurs
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isBlocking
public final boolean isBlocking()Description copied from class:SelectableChannel
Tells whether or not every I/O operation on this channel will block until it completes. A newly-created channel is always in blocking mode.If this channel is closed then the value returned by this method is not specified.
- Specified by:
isBlocking
in classSelectableChannel
- Returns:
true
if, and only if, this channel is in blocking mode
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blockingLock
Description copied from class:SelectableChannel
Retrieves the object upon which theconfigureBlocking
andregister
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.- Specified by:
blockingLock
in classSelectableChannel
- Returns:
- The blocking-mode lock object
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configureBlocking
Adjusts this channel's blocking mode.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.- Specified by:
configureBlocking
in classSelectableChannel
- Parameters:
block
- Iftrue
then this channel will be placed in blocking mode; iffalse
then it will be placed non-blocking mode- Returns:
- This selectable channel
- Throws:
ClosedChannelException
- If this channel is closedIOException
- If an I/O error occurs
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implConfigureBlocking
Adjusts this channel's blocking mode.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.- Parameters:
block
- Iftrue
then this channel will be placed in blocking mode; iffalse
then it will be placed non-blocking mode- Throws:
IOException
- If an I/O error occurs
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