Name
Selector
Synopsis
A Selector
is an object that monitors multiple
nonblocking SelectableChannel objects and (after
blocking if necessary) “selects”
the channel that is (or the channels that are) ready for I/O. Create
a new Selector with the static open(
) method. Next register the channels that it is to monitor:
a channel is registered by passing the Selector to
the register( ) method of the channel
(register( ) is defined by the abstract
SelectableChannel class). In addition to the
Selector you must also pass a bitmask that
specifies which I/O operations (reading, writing, connecting, and
accepting) that the Selector is to monitor for
that channel. Each call to this register( ) method
returns a SelectionKey object. (The
SelectionKey class also defines the constants that
are used to form the bitmask of I/O operations.) Note that before a
SelectableChannel can be registered, it must be in
nonblocking mode, which can be accomplished with the
configureBlocking( ) method of
SelectableChannel.
Once the channels are registered with the
Selector, call select(
)
to block until one or more of the
channels is ready for I/O. One version of select(
) takes a timeout value and returns if the specified number
of milliseconds elapses without any channels becoming ready for I/O.
These methods also return if any of the channels is closed, if an
error occurs on any channel, if the wakeup( )
method of the Selector is called, or if the
interrupt( ) method of the blocked thread is called. There is ...
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