04 05 UniThreaded TCP

import java.util.*;
import java.io.*;
import java.net.*;

public class Server extends Thread {
  private ServerSocket server_socket;

  public Server(int port_no) throws IOException {
    while (true) {
      try {
        server_socket = new ServerSocket(port_no);

        System.out.println("Waiting for client to connect");

        Socket server = server_socket.accept();
        System.out.println("Connected to client");

        DataOutputStream out = new DataOutputStream(server.getOutputStream());
        String server_message = "Hi there! Enter something";
        out.writeUTF(server_message);

        DataInputStream in = new DataInputStream(server.getInputStream());
        String client_reply = in.readUTF();
        System.out.println("User replied with: " + client_reply);
        server.close();
      } catch (Exception e) {
        e.printStackTrace();
      }
    }
  }

  public static void main(String[] args) throws IOException {
    Thread t1 = new Server(5000);
    t1.start();
  }
}

import java.util.*;
import java.io.*;
import java.net.*;

public class Client
{
  public Client(String host, int port) throws IOException
  {
    try
    {
      Socket client = new Socket(host, port);

      System.out.println("Connected to server");

      DataInputStream in = new DataInputStream(client.getInputStream());

      String server_message = in.readUTF();
      System.out.println(server_message);

      DataOutputStream out = new DataOutputStream(client.getOutputStream());

      Scanner user_in = new Scanner(System.in);
      String client_reply = user_in.next();
      out.writeUTF(client_reply);

      user_in.close();
      client.close();
    } catch (Exception e)
    {
      e.printStackTrace();
    }
  }
  public static void main(String[] args) throws IOException
  {
    new Client("localhost", 5000);
  }
}

javac Server.java
java Server

javac Client.java
java Client

import java.util.*;
import java.io.*;
import java.net.*;

public class Server extends Thread {
    private ServerSocket server_socket;

    public Server(int port_no) throws IOException {
        while (true) {
            try {
                server_socket = new ServerSocket(port_no);

                System.out.println("Waiting for client to connect");

                Socket server = server_socket.accept();
                System.out.println("Connected to client");

                DataOutputStream out = new DataOutputStream(server.getOutputStream());
                String server_message = "Hi there! Enter something";
                out.writeUTF(server_message);

                DataInputStream in = new DataInputStream(server.getInputStream());

                int num1 = Integer.parseInt(in.readUTF());
                String op = in.readUTF();
                int num2 = Integer.parseInt(in.readUTF());

                String client_reply = "Received: " + num1 + op + num2;
                System.out.println(client_reply);

                int result = 0;

                switch(op)
                {
                    case "+": {result = num1 + num2; break;}
                    case "-": {result = num1 - num2; break;}
                    case "*": {result = num1 * num2; break;}
                    case "/": {result = num1 / num2; break;}
                    case "^": {result = num1 ^ num2; break;}
                    default: {System.out.println("Invalid Operator");}
                }

                out.writeUTF(Integer.toString(result));

                server.close();
            } catch (Exception e) {
        e.printStackTrace();
            }
        }
    }

    public static void main(String[] args) throws IOException {
        Thread t1 = new Server(args[0]);
        t1.start();
    }
}

import java.util.*;
import java.io.*;
import java.net.*;

public class Client {
    public Client(String host, int port) throws IOException
  {
    try
    {
      Socket client = new Socket(host, port);

      System.out.println("Connected to server");

      DataInputStream in = new DataInputStream(client.getInputStream());

      String server_message = in.readUTF();
      System.out.println(server_message);

      DataOutputStream out = new DataOutputStream(client.getOutputStream());

      Scanner user_in = new Scanner(System.in);

      int num1 = user_in.nextInt();
      String op = user_in.next();
      int num2 = user_in.nextInt();

      out.writeUTF(Integer.toString(num1));
      out.writeUTF(op);
      out.writeUTF(Integer.toString(num2));


      String result = in.readUTF();
      System.out.println(result);

      user_in.close();
      client.close();
    } catch (Exception e)
    {
      e.printStackTrace();
    }
  }

    public static void main(String[] args) throws IOException {
        new Client(args[0], args[1]);
    }
}

javac Server.java
java Server 5000

javac Client.java
java Client localhost 5000

import java.util.*;
import java.io.*;
import java.net.*;

public class Server extends Thread {
  private ServerSocket server_socket;

  public Server(int port_no) throws IOException {
    while (true) {
      try {
        server_socket = new ServerSocket(port_no);

        System.out.println("Waiting for client to connect");

        Socket server = server_socket.accept();
        System.out.println("Connected to client");

        PrintWriter out = new PrintWriter(server.getOutputStream());
        String server_message = "Hi there! Enter something";
        out.print(server_message);

        BufferedReader in = new BufferedReader(new InputStreamReader(
            server.getInputStream()
        ));
        String client_reply = in.readLine();

        System.out.println("User replied with: " + client_reply);
        server.close();
      } catch (Exception e) {
        e.printStackTrace();
      }
    }
  }

  public static void main(String[] args) throws IOException {
    Thread t1 = new Server(5000);
    t1.start();
  }
}

javac Server.java
java Server 5000
telnet localhost 5000