NiO example

Server side

package com.mang.NIO.nsync;


import java.io.IOException;
import java.io.PrintStream;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
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;
import java.util.Set;

public class EchoServer {
    
    private Selector selector = null;
    private ServerSocketChannel serverSocketChannel = null;
    private int port = 8000;
    private Charset charset = Charset.forName("GBK");

    public EchoServer() throws IOException {
    
        this.selector = Selector.open();
        this.serverSocketChannel = ServerSocketChannel.open();
        this.serverSocketChannel.socket().setReuseAddress(true);
        this.serverSocketChannel.configureBlocking(false);
        this.serverSocketChannel.socket().bind(new InetSocketAddress(this.port));
        System.out.println(" Server startup ");
    }

    public void service() throws IOException {
    
        this.serverSocketChannel.register(this.selector, SelectionKey.OP_ACCEPT);

        while(this.selector.select() > 0) {
    
            Set readyKeys = this.selector.selectedKeys();
            Iterator it = readyKeys.iterator();

            while(it.hasNext()) {
    
                SelectionKey key = null;

                try {
    
                    key = (SelectionKey)it.next();
                    it.remove();
                    if (key.isAcceptable()) {
    
                        ServerSocketChannel ssc = (ServerSocketChannel)key.channel();
                        SocketChannel socketChannel = ssc.accept();
                        PrintStream var10000 = System.out;
                        InetAddress var10001 = socketChannel.socket().getInetAddress();
                        var10000.println(" Customer connection received , come from :" + var10001 + ":" + socketChannel.socket().getPort());
                        socketChannel.configureBlocking(false);
                        ByteBuffer buffer = ByteBuffer.allocate(1024);
                        socketChannel.register(this.selector, 5, buffer);
                    }

                    if (key.isReadable()) {
    
                        this.receive(key);
                    }

                    if (key.isWritable()) {
    
                        this.send(key);
                    }
                } catch (IOException var8) {
    
                    var8.printStackTrace();

                    try {
    
                        if (key != null) {
    
                            key.cancel();
                            key.channel().close();
                        }
                    } catch (Exception var7) {
    
                        var8.printStackTrace();
                    }
                }
            }
        }

    }

    public void send(SelectionKey key) throws IOException {
    
        ByteBuffer buffer = (ByteBuffer)key.attachment();
        SocketChannel socketChannel = (SocketChannel)key.channel();
        buffer.flip();
        String data = this.decode(buffer);
        if (data.indexOf("\r\n") != -1) {
    
            String outputData = data.substring(0, data.indexOf("\n") + 1);
            System.out.print(outputData);
            ByteBuffer outputBuffer = this.encode("echo:" + outputData);

            while(outputBuffer.hasRemaining()) {
    
                socketChannel.write(outputBuffer);
            }

            ByteBuffer temp = this.encode(outputData);
            buffer.position(temp.limit());
            buffer.compact();
            if (outputData.equals("bye\r\n")) {
    
                key.cancel();
                socketChannel.close();
                System.out.println(" Close the connection with the customer ");
            }

        }
    }

    public void receive(SelectionKey key) throws IOException {
    
        ByteBuffer buffer = (ByteBuffer)key.attachment();
        SocketChannel socketChannel = (SocketChannel)key.channel();
        ByteBuffer readBuff = ByteBuffer.allocate(32);
        socketChannel.read(readBuff);
        readBuff.flip();
        buffer.limit(buffer.capacity());
        buffer.put(readBuff);
    }

    public String decode(ByteBuffer buffer) {
    
        CharBuffer charBuffer = this.charset.decode(buffer);
        return charBuffer.toString();
    }

    public ByteBuffer encode(String str) {
    
        return this.charset.encode(str);
    }

    public static void main(String[] args) throws Exception {
    
        EchoServer server = new EchoServer();
        server.service();
    }
}

client

package com.mang.NIO.nsync;

import jdk.internal.util.xml.impl.Input;

import java.io.*;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.nio.channels.SocketChannel;

public class EchoClient {
    
    private SocketChannel socketChannel = null;

    public EchoClient() throws IOException {
    
        socketChannel = SocketChannel.open();
        InetAddress ia  = InetAddress.getLocalHost();
        InetSocketAddress isa = new InetSocketAddress(ia,8000);
        socketChannel.connect(isa);
        System.out.println(" The connection with the server is established successfully ");
    }

    public static void main(String[] args) throws IOException {
    
        new EchoClient().talk();
    }

    private PrintWriter getWriter(Socket socket) throws IOException {
    
        OutputStream socketOut = socket.getOutputStream();
        return new PrintWriter(socketOut,true);
    }

    private BufferedReader getReader(Socket socket) throws IOException {
    
        InputStream socketIn = socket.getInputStream();
        return new BufferedReader(new InputStreamReader(socketIn));
    }

    public void talk() {
    
        try {
    
            BufferedReader br = getReader(socketChannel.socket());
            PrintWriter pw = getWriter(socketChannel.socket());
            BufferedReader localReader = new BufferedReader(new InputStreamReader(System.in));
            String msg = null;
            while((msg=localReader.readLine())!=null){
    
                pw.println(msg);
                System.out.println(br.readLine());

                if(msg.equals("bye")) {
    
                    break;
                }
            }
        } catch (IOException e) {
    
            e.printStackTrace();
        } finally {
    

            try {
    
                socketChannel.close();
            } catch (IOException e) {
    
                e.printStackTrace();
            }
        }
    }


}