public abstract class AbstractSelectableChannel extends SelectableChannel
Base implementation class for selectable channels.
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 abstract protected methods defined in this class need not synchronize against other threads that might be engaged in the same operations.
protected AbstractSelectableChannel(SelectorProvider provider)
Initializes a new instance of this class.
provider - The provider that created this channelpublic final SelectorProvider provider()
Returns the provider that created this channel.
provider in class SelectableChannel
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.
isRegistered in class SelectableChannel
true if, and only if, this channel is registeredpublic final SelectionKey keyFor(Selector sel)
Description copied from class: SelectableChannel
Retrieves the key representing the channel's registration with the given selector.
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 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.
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 Closes this channel.
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 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.
IOException - If an I/O error occurspublic 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.
isBlocking in class SelectableChannel
true if, and only if, this channel is in blocking modepublic final Object blockingLock()
Description copied from class: SelectableChannel
Retrieves the object upon which the 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 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.
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 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.
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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