// 初始化一个 serverSocketChannel
serverSocketChannel = ServerSocketChannel.open();
serverSocketChannel.bind(new InetSocketAddress(8000));
// 设置serverSocketChannel为非阻塞模式
// 即 accept()会立即得到返回
serverSocketChannel.configureBlocking(false);

public class TraditionalSocketDemo {

	public static void main(String[] args) throws IOException {
		ServerSocket serverSocket = new ServerSocket(7777);
		System.out.println("服务端启动...");
		while (true) {
			// 获取socket套接字
			// accept()阻塞点
			Socket socket = serverSocket.accept();
			System.out.println("有新客户端连接上来了...");
			// 获取客户端输入流
			java.io.InputStream is = socket.getInputStream();
			byte[] b = new byte[1024];
			while (true) {
				// 循环读取数据
				// read() 阻塞点
				int data = is.read(b);
				if (data != -1) {
					String info = new String(b, 0, data, "GBK");
					System.out.println(info);
				} else {
					break;
				}
			}
		}
	}
}

public class TraditionalSocketDemo2 {

	public static void main(String[] args) throws IOException {
		ServerSocket serverSocket = new ServerSocket(7777);
		System.out.println("服务端启动...");
		while (true) {
			// 获取socket套接字
			// accept()阻塞点
			final Socket socket = serverSocket.accept();
			System.out.println("有新客户端连接上来了...");
			new Thread(new Runnable() {
				@Override
				public void run() {
					try {
						// 获取客户端输入流
						InputStream is = socket.getInputStream();
						byte[] b = new byte[1024];
						while (true) {
							// 循环读取数据
							// read() 阻塞点
							int data = is.read(b);
							if (data != -1) {
								String info = new String(b, 0, data, "GBK");
								System.out.println(info);
							} else {
								break;
							}
						}
					} catch (Exception e) {
						e.printStackTrace();
					}
				}
			}).start();
		}
	}
}

public class NioServer {

    private int port;
    private Selector selector;
    private ExecutorService service = Executors.newFixedThreadPool(5);

    public static void main(String[] args){
        new NioServer(8080).start();
    }

    public NioServer(int port) {
        this.port = port;
    }

    public void init() {
        ServerSocketChannel ssc = null;
        try {
            ssc = ServerSocketChannel.open();
            ssc.configureBlocking(false);
            ssc.bind(new InetSocketAddress(port));
            selector = Selector.open();
            ssc.register(selector, SelectionKey.OP_ACCEPT);
            System.out.println("NioServer started ......");
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
        }
    }

    public void accept(SelectionKey key) {
        try {
            ServerSocketChannel ssc = (ServerSocketChannel) key.channel();
            SocketChannel sc = ssc.accept();
            sc.configureBlocking(false);
            sc.register(selector, SelectionKey.OP_READ);
            System.out.println("accept a client : " + sc.socket().getInetAddress().getHostName());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void start() {
        this.init();
        while (true) {
            try {
                int events = selector.select();
                if (events > 0) {
                    Iterator<SelectionKey> selectionKeys = selector.selectedKeys().iterator();
                    while (selectionKeys.hasNext()) {
                        SelectionKey key = selectionKeys.next();
                        selectionKeys.remove();
                        if (key.isAcceptable()) {
                            accept(key);
                        } else {
                            service.submit(new NioServerHandler(key));
                        }
                    }
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    public static class NioServerHandler implements Runnable{

        private SelectionKey selectionKey;

        public NioServerHandler(SelectionKey selectionKey) {
            this.selectionKey = selectionKey;
        }

        @Override
        public void run() {
            try {
                if (selectionKey.isReadable()) {
                    SocketChannel socketChannel = (SocketChannel) selectionKey.channel();
                    ByteBuffer buffer = ByteBuffer.allocate(1024);
                    socketChannel.read(buffer);
                    buffer.flip();
                    System.out.println("收到客户端"+socketChannel.socket().getInetAddress().getHostName()+"的数据："+new String(buffer.array()));
                    //将数据添加到key中
                    ByteBuffer outBuffer = ByteBuffer.wrap(buffer.array());
                    socketChannel.write(outBuffer);// 将消息回送给客户端
                    selectionKey.cancel();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

public class NioClient {
    private static final String host = "127.0.0.1";
    private static final int port = 8080;
    private Selector selector;

    public static void main(String[] args){
        for (int i=0;i<3;i++) {
            new Thread(new Runnable() {
                @Override
                public void run() {
                    NioClient client = new NioClient();
                    client.connect(host, port);
                    client.listen();
                }
            }).start();
        }
    }

    public void connect(String host, int port) {
        try {
            SocketChannel sc = SocketChannel.open();
            sc.configureBlocking(false);
            this.selector = Selector.open();
            sc.register(selector, SelectionKey.OP_CONNECT);
            sc.connect(new InetSocketAddress(host, port));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void listen() {
        while (true) {
            try {
                int events = selector.select();
                if (events > 0) {
                    Iterator<SelectionKey> selectionKeys = selector.selectedKeys().iterator();
                    while (selectionKeys.hasNext()) {
                        SelectionKey selectionKey = selectionKeys.next();
                        selectionKeys.remove();
                        //连接事件
                        if (selectionKey.isConnectable()) {
                            SocketChannel socketChannel = (SocketChannel) selectionKey.channel();
                            if (socketChannel.isConnectionPending()) {
                                socketChannel.finishConnect();
                            }

                            socketChannel.configureBlocking(false);
                            socketChannel.register(selector, SelectionKey.OP_READ);
                            socketChannel.write(ByteBuffer.wrap(("Hello this is " + Thread.currentThread().getName()).getBytes()));
                        } else if (selectionKey.isReadable()) {
                            SocketChannel sc = (SocketChannel) selectionKey.channel();
                            ByteBuffer buffer = ByteBuffer.allocate(1024);
                            sc.read(buffer);
                            buffer.flip();
                            System.out.println("收到服务端的数据："+new String(buffer.array()));
                        }
                    }
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}