Java NIO 简单例子

服务器端：

package nioT;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.nio.charset.Charset;
import java.util.Iterator;

public class NIOServer1 {
	// 本地字符集
	private static final String LocalCharSetName = "UTF-8";

	// 本地服务器监听的端口
	private static final int Listenning_Port = 8888;

	// 缓冲区大小
	private static final int Buffer_Size = 1024;

	// 超时时间,单位毫秒
	private static final int TimeOut = 3000;

	public static void main(String[] args) throws IOException {
		// 创建一个在本地端口进行监听的服务Socket信道.并设置为非阻塞方式
		ServerSocketChannel serverChannel = ServerSocketChannel.open();

		serverChannel.socket().bind(new InetSocketAddress(Listenning_Port));
		serverChannel.configureBlocking(false);

		// 创建一个选择器并将serverChannel注册到它上面
		Selector selector = Selector.open();
		serverChannel.register(selector, SelectionKey.OP_ACCEPT);

		while (true) {
			// 等待某个信道就绪
			if (selector.select(TimeOut) == 0) {
				System.out.println(".");
				continue;
			}

			// 获得就绪信道的键迭代器
			Iterator keyIter = selector.selectedKeys().iterator();

			// 使用迭代器进行遍历就绪信道
			while (keyIter.hasNext()) {
				SelectionKey key = keyIter.next();
				// 这种情况是有客户端连接过来,准备一个clientChannel与之通信
				if (key.isAcceptable()) {
					SocketChannel clientChannel = ((ServerSocketChannel) key.channel()).accept();
					clientChannel.configureBlocking(false);
					clientChannel.register(selector, SelectionKey.OP_READ,
							ByteBuffer.allocate(Buffer_Size));
				}

				// 客户端有写入时
				if (key.isReadable()) {
					// 获得与客户端通信的信道
					SocketChannel clientChannel = (SocketChannel) key.channel();

					// 得到并重置缓冲区的主要索引值
					ByteBuffer buffer = (ByteBuffer) key.attachment();
					buffer.clear();

					// 读取信息获得读取的字节数
					long bytesRead = clientChannel.read(buffer);

					if (bytesRead == -1) {
						// 没有读取到内容的情况
						clientChannel.close();
					} else {
						// 将缓冲区准备为数据传出状态
						buffer.flip();
						// 将获得字节字符串(使用Charset进行解码)
						String receivedString = Charset
								.forName(LocalCharSetName).newDecoder().decode(buffer).toString();

						// 控制台打印出来
						System.out.println("接收到信息:" + receivedString);

						// 准备发送的文本
						String sendString = "你好,客户端. 已经收到你的信息" + receivedString;

						// 将要发送的字符串编码(使用Charset进行编码)后再进行包装
						buffer = ByteBuffer.wrap(sendString.getBytes(LocalCharSetName));

						// 发送回去
						clientChannel.write(buffer);

						// 设置为下一次读取或是写入做准备
						key.interestOps(SelectionKey.OP_READ | SelectionKey.OP_WRITE);
					}
				}

				keyIter.remove();
			}
		}

	}
}

客户端：

package nioT;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;
import java.util.Scanner;

public class NIOClient1Test {

	public static void main(String[] args) throws UnknownHostException,
			IOException {
		Socket s = new Socket("localhost", 8888);

		InputStream inStream = s.getInputStream();
		OutputStream outStream = s.getOutputStream();

		// 输出
		PrintWriter out = new PrintWriter(outStream, true);
		out.println("getPublicKey你好！");
		out.flush();

		s.shutdownOutput();// 输出结束

		// 输入
		Scanner in = new Scanner(inStream);

		StringBuilder sb = new StringBuilder();
		while (in.hasNextLine()) {
			String line = in.nextLine();
			sb.append(line);
		}

		String response = sb.toString();
		System.out.println("response=" + response);

	}
}

运行结果

服务端：

.
接收到信息:getPublicKey你好！

.

客户端：

response=你好,客户端. 已经收到你的信息getPublicKey你好！