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Added in API level 1

AbstractSelectableChannel

public abstract class AbstractSelectableChannel
extends SelectableChannel

java.lang.Object
   ↳ java.nio.channels.spi.AbstractInterruptibleChannel
     ↳ java.nio.channels.SelectableChannel
       ↳ java.nio.channels.spi.AbstractSelectableChannel
Known Direct Subclasses


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.

Summary

Protected constructors

AbstractSelectableChannel(SelectorProvider provider)

Initializes a new instance of this class.

Public methods

final Object blockingLock()

Retrieves the object upon which the configureBlocking and register methods synchronize.

final SelectableChannel configureBlocking(boolean block)

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(Selector sel)

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(Selector sel, int ops, Object att)

Registers this channel with the given selector, returning a selection key.

Protected methods

final void implCloseChannel()

Closes this channel.

abstract void implCloseSelectableChannel()

Closes this selectable channel.

abstract void implConfigureBlocking(boolean block)

Adjusts this channel's blocking mode.

Inherited methods

From class java.nio.channels.SelectableChannel
From class java.nio.channels.spi.AbstractInterruptibleChannel
From class java.lang.Object
From interface java.nio.channels.Channel
From interface java.nio.channels.InterruptibleChannel
From interface java.io.Closeable
From interface java.lang.AutoCloseable

Protected constructors

AbstractSelectableChannel

Added in API level 1
AbstractSelectableChannel (SelectorProvider provider)

Initializes a new instance of this class.

Parameters
provider SelectorProvider

Public methods

blockingLock

Added in API level 1
Object blockingLock ()

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.

Returns
Object The blocking-mode lock object

configureBlocking

Added in API level 1
SelectableChannel configureBlocking (boolean block)

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.

Parameters
block boolean: If true then this channel will be placed in blocking mode; if false then it will be placed non-blocking mode
Returns
SelectableChannel This selectable channel
Throws
IOException

isBlocking

Added in API level 1
boolean isBlocking ()

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.

Returns
boolean true if, and only if, this channel is in blocking mode

isRegistered

Added in API level 1
boolean isRegistered ()

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.

Returns
boolean true if, and only if, this channel is registered

keyFor

Added in API level 1
SelectionKey keyFor (Selector sel)

Retrieves the key representing the channel's registration with the given selector.

Parameters
sel Selector
Returns
SelectionKey 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

provider

Added in API level 1
SelectorProvider provider ()

Returns the provider that created this channel.

Returns
SelectorProvider The provider that created this channel

register

Added in API level 1
SelectionKey register (Selector sel, 
                int ops, 
                Object att)

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.

Parameters
sel Selector: The selector with which this channel is to be registered
ops int: The interest set for the resulting key
att Object: The attachment for the resulting key; may be null
Returns
SelectionKey A key representing the registration of this channel with the given selector
Throws
ClosedSelectorException
IllegalBlockingModeException
IllegalSelectorException
CancelledKeyException
IllegalArgumentException
ClosedChannelException

Protected methods

implCloseChannel

Added in API level 1
void implCloseChannel ()

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.

Throws
IOException

implCloseSelectableChannel

Added in API level 1
void 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

implConfigureBlocking

Added in API level 1
void implConfigureBlocking (boolean block)

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 boolean
Throws
IOException If an I/O error occurs
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