java7 nio 例子

/**
 * 
 */
package Test;

import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;

/**
 * 
 * @author Administrator
 * @version
 */

public class NBTest {

	/** Creates new NBTest */
	public NBTest() {
	}

	public void startServer() throws Exception {
		int channels = 0;
		int nKeys = 0;
		int currentSelector = 0;

		// 使用Selector
		Selector selector = Selector.open();

		// 建立Channel 並綁定到9000端口
		ServerSocketChannel ssc = ServerSocketChannel.open();
		InetSocketAddress address = new InetSocketAddress(
				InetAddress.getLocalHost(), 9000);
		ssc.socket().bind(address);

		// 使設定non-blocking的方式。
		ssc.configureBlocking(false);

		// 向Selector註冊Channel及我們有興趣的事件
		SelectionKey s = ssc.register(selector, SelectionKey.OP_ACCEPT);
		printKeyInfo(s);

		while (true) // 不斷的輪詢
		{
			debug("NBTest: Starting select");

			// Selector通過select方法通知我們我們感興趣的事件發生了。
			nKeys = selector.select();
			// 如果有我們註冊的事情發生了，它的傳回值就會大於0
			if (nKeys > 0) {
				debug("NBTest: Number of keys after select operation: " + nKeys);

				// Selector傳回一組SelectionKeys
				// 我們從這些key中的channel()方法中取得我們剛剛註冊的channel。
				Set selectedKeys = selector.selectedKeys();
				Iterator i = selectedKeys.iterator();
				while (i.hasNext()) {
					s = (SelectionKey) i.next();
					printKeyInfo(s);
					debug("NBTest: Nr Keys in selector: "
							+ selector.keys().size());

					// 一個key被處理完成後，就都被從就緒關鍵字（ready keys）列表中除去
					i.remove();
					if (s.isAcceptable()) {
						// 從channel()中取得我們剛剛註冊的channel。
						Socket socket = ((ServerSocketChannel) s.channel())
								.accept().socket();
						SocketChannel sc = socket.getChannel();

						sc.configureBlocking(false);
						sc.register(selector, SelectionKey.OP_READ
								| SelectionKey.OP_WRITE);
						System.out.println(++channels);
					} else {
						debug("NBTest: Channel not acceptable");
					}
				}
			} else {
				debug("NBTest: Select finished without any keys.");
			}

		}

	}

	private static void debug(String s) {
		System.out.println(s);
	}

	private static void printKeyInfo(SelectionKey sk) {
		String s = new String();

		s = "Att: " + (sk.attachment() == null ? "no" : "yes");
		s += ", Read: " + sk.isReadable();
		s += ", Acpt: " + sk.isAcceptable();
		s += ", Cnct: " + sk.isConnectable();
		s += ", Wrt: " + sk.isWritable();
		s += ", Valid: " + sk.isValid();
		s += ", Ops: " + sk.interestOps();
		debug(s);
	}

	/**
	 * @param args
	 *            the command line arguments
	 */
	public static void main(String args[]) {
		NBTest nbTest = new NBTest();
		try {
			nbTest.startServer();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

}