NiO implementation

Server implementation ：

public static void main(String[] args) {
    
        int port = 7236;
        //NIO Multiplexing 
        // Creating a thread pool 
        ThreadPoolExecutor threadPool = new ThreadPoolExecutor(4, 4, 60L, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>());
        threadPool.execute(new Runnable() {
    
            @Override
            public void run() {
    
                try (Selector selector = Selector.open();
                     //ServerSocketChannel The construction method uses Protected Embellished 
                     ServerSocketChannel serverSocketChannel = ServerSocketChannel.open()) {
    
                    // Binding services 
                    serverSocketChannel.bind(new InetSocketAddress(InetAddress.getLocalHost(), port));
                    /*  Set up  SocketChannel  Is non-blocking mode   After setting , You can call... In asynchronous mode connect(), read()  and write() 了  */
                    serverSocketChannel.configureBlocking(false);
                    //
                    serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
                    while (true) {
    
                        selector.select();// Block waiting for ready Channel
                        //
                        Set<SelectionKey> selectionKeys = selector.selectedKeys();
                        Iterator<SelectionKey> iterator = selectionKeys.iterator();
                        while (iterator.hasNext()) {
    
                            SelectionKey key = iterator.next();
                            try (SocketChannel channel = ((ServerSocketChannel) key.channel()).accept();) {
    
                                channel.write(Charset.defaultCharset().encode(" Hello , The world -zzd"));
                            }
                            iterator.remove();
                        }
                    }
                } catch (IOException e) {
    
                    e.printStackTrace();
                }
            }
        });

    }

Client implementation ：

public static void main(String[] args) {
    
        int port = 7236;
        //Socket client （ Receive information and print ）
        try(Socket socket = new Socket(InetAddress.getLocalHost(), port)){
    
            BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            reader.lines().forEach(s-> System.out.println(" client ：" + s));
        } catch (UnknownHostException e) {
    
            e.printStackTrace();
        } catch (IOException e) {
    
            e.printStackTrace();
        }
    }

Explanation of calling process ：

• First , adopt Selector.open() Create a Selector, As a dispatcher like role
• then , Create a ServerSocketChannel, And to the Selector register , By designation SelectionKey.OP_ACCEPT, Tell the dispatcher , It focuses on newly established connection requests
• Why should we explicitly configure non blocking mode ？ This is because in blocking mode , Registration is not allowed , Will throw out IllegalBlockingModeException abnormal
• Selector Blocked in select operation , When there is Channel An access request has occurred , Will be awakened