Class AbstractSelectableChannel
- java.lang.Object
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- java.nio.channels.spi.AbstractInterruptibleChannel
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- java.nio.channels.SelectableChannel
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- java.nio.channels.spi.AbstractSelectableChannel
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- All Implemented Interfaces:
- Closeable, AutoCloseable, Channel, InterruptibleChannel
- Direct Known Subclasses:
- DatagramChannel, Pipe.SinkChannel, Pipe.SourceChannel, ServerSocketChannel, SocketChannel
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.- Since:
- 1.4
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Constructor Summary
Constructors Modifier Constructor and Description protected
AbstractSelectableChannel(SelectorProvider provider)
Initializes a new instance of this class.
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Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method and Description Object
blockingLock()
Retrieves the object upon which theconfigureBlocking
andregister
methods synchronize.SelectableChannel
configureBlocking(boolean block)
Adjusts this channel's blocking mode.protected void
implCloseChannel()
Closes this channel.protected abstract void
implCloseSelectableChannel()
Closes this selectable channel.protected abstract void
implConfigureBlocking(boolean block)
Adjusts this channel's blocking mode.boolean
isBlocking()
Tells whether or not every I/O operation on this channel will block until it completes.boolean
isRegistered()
Tells whether or not this channel is currently registered with any selectors.SelectionKey
keyFor(Selector sel)
Retrieves the key representing the channel's registration with the given selector.SelectorProvider
provider()
Returns the provider that created this channel.SelectionKey
register(Selector sel, int ops, Object att)
Registers this channel with the given selector, returning a selection key.-
Methods inherited from class java.nio.channels.SelectableChannel
register, validOps
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Methods inherited from class java.nio.channels.spi.AbstractInterruptibleChannel
begin, close, end, isOpen
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Constructor Detail
AbstractSelectableChannel
protected AbstractSelectableChannel(SelectorProvider provider)
Initializes a new instance of this class.- Parameters:
-
provider
- The provider that created this channel
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Method Detail
provider
public final SelectorProvider provider()
Returns the provider that created this channel.- Specified by:
-
provider
in classSelectableChannel
- Returns:
- The provider that created this channel
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
keyFor
public final SelectionKey keyFor(Selector sel)
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
register
public 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.- Specified by:
-
register
in classSelectableChannel
- Parameters:
-
sel
- The selector with which this channel is to be registered -
ops
- The interest set for the resulting key -
att
- The attachment for the resulting key; may be null - Returns:
- A key representing the registration of this channel with the given selector
- Throws:
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ClosedSelectorException
- If the selector is closed -
IllegalBlockingModeException
- If this channel is in blocking mode -
IllegalSelectorException
- If this channel was not created by the same provider as the given selector -
CancelledKeyException
- If this channel is currently registered with the given selector but the corresponding key has already been cancelled -
IllegalArgumentException
- If a bit in the ops set does not correspond to an operation that is supported by this channel, that is, ifset & ~validOps() != 0
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ClosedChannelException
- If this channel is closed
implCloseChannel
protected final void implCloseChannel() throws IOException
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
implCloseSelectableChannel
protected 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.
- Throws:
-
IOException
- If an I/O error occurs
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
blockingLock
public final Object 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
configureBlocking
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.- Specified by:
-
configureBlocking
in classSelectableChannel
- Parameters:
-
block
- If true then this channel will be placed in blocking mode; if false then it will be placed non-blocking mode - Returns:
- This selectable channel
- Throws:
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ClosedChannelException
- If this channel is closed -
IOException
- If an I/O error occurs
implConfigureBlocking
protected 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.- Parameters:
-
block
- If true then this channel will be placed in blocking mode; if false then it will be placed non-blocking mode - Throws:
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IOException
- If an I/O error occurs
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Submit a bug or feature
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