Trang Máy Chủ :

import java.io.*;

import java.net.*;

class TCPSC

{

          public static void main(String[] args) throws Exception

          {

                   int port = 2812;

                   ServerSocket server = new ServerSocket(port);

                   Socket client = server.accept();

                   BufferedReader br = new BufferedReader(new

                             InputStreamReader(client.getInputStream()));

                   PrintWriter pw = new PrintWriter(client.getOutputStream());

                   String st = br.readLine();

                   String kq = XuLy(st);

                   pw.write(kq + "

");

                   pw.flush();

                   pw.close();

                   br.close();

                   client.close();

                   server.close();

          }

          public static String XuLy(String st)

          {

                   return st.toUpperCase();

          }

}

Trang Máy Khách :

import java.io.*;

import java.net.*;

class TCPCC

{

          public static void main(String[] args) throws Exception

          {

                   int portS = 2812;

                   InetAddress ipS = InetAddress.getByName("localhost");

                   Socket server = new Socket(ipS,portS);

                   BufferedReader in = new BufferedReader(new

                             InputStreamReader(System.in));

                   BufferedReader br = new BufferedReader(new

                             InputStreamReader(server.getInputStream()));

                   PrintWriter pw = new PrintWriter(server.getOutputStream());

                   System.out.print("Nhap chuoi bat ky : ");

                   String st = in.readLine();

                   pw.write(st+"

");

                   pw.flush();

                   String kq = br.readLine();

                   System.out.println("Chuoi Hoa : " + kq);

                   pw.close();

                   br.close();

                   server.close();

          }

}