In Java, multiplexing (Multiplexing) usually refers to managing multiple channels through one thread, so as to realize the IO operation of multiple channels at the same time.
Java NIO (New IO) provides a multiplexing mechanism, which is the Selector mechanism. Selector can listen to IO events of multiple channels (such as connection, read, write events, etc.), and assign the events to corresponding threads for processing. Using the Selector mechanism can greatly improve the IO efficiency of the application.
The basic flow of the Selector mechanism is as follows:
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Create a Selector instance.
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Register the channel (such as SocketChannel, ServerSocketChannel, etc.) to the Selector, and set the type of event to monitor (such as read, write, connect, etc.).
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The select() method of Selector is called continuously and cyclically, waiting for the occurrence of IO events.
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When a registered event type occurs on a channel, the Selector will return a set of selected channels (SelectionKey).
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Traverse the selected channel collection, and execute corresponding processing logic according to different event types of the channel.
Using the multiplexing mechanism allows one thread to process multiple channels, avoiding the overhead caused by thread switching. At the same time, the multiplexing mechanism can effectively avoid the problem of low IO efficiency such as polling blocking.