|
New I/0 Functionality for JavaTM 2 Standard Edition 1.4(9) Now comes the interesting part, and what people are most interested in in the new I/O packages. How do you configure the channel connection to non-blocking? The basic step is to call the configureBlocking method on the opened SocketChannel, and pass in a value of false. Once you call the connect method, the method now returns immediately. String host = ...;InetSocketAddress socketAddress =new InetSocketAddress(host, 80);channel = SocketChannel.open();channel.configureBlocking(false);channel.connect(socketAddress); Once you have a non-blocking channel, you then have to figure out how to actually work with the channel. The SocketChannel is an example of a SelectableChannel. These selectable channels work with a Selector. Basically, you register the channel with the Selector, tell the Selector what events you are interested in, and it notifies you when something interesting happens. To get a Selector instance, just call the static open method of the class: Selector selector = Selector.open(); Registering with the Selector is done through the register method of the channel. The events are specified by fields of the SelectionKey class. In the case of the SocketChannel class, the available operations are OP_CONNECT, OP_READ, and OP_WRITE. So, if you were interested in read and connection operations, you would register as follows: channel.register(selector,SelectionKey.OP_CONNECT SelectionKey.OP_READ); At this point, you have to wait on the selector to tell you when events of interest happen on registered channels. The select method of the Selector will block until something interesting happens. To find this out, you can put a while (selector.select() > 0) loop in its own thread and then go off and do your own thing while the I/O events are being processed. The select method returns when something happens, where the value returned is the count of channels ready to be acted upon. This value doesn't really matter though.
| 
