Question

In the provided client and server code, the server can serve to single client at a time. You have to change server.java code so that it can connect and serve multiple clients at the same time. Use multithreading.
===============================================================================
import java.io.*;

import java.net.*;

public class Client {

    public static void main(String[] args) throws IOException {

        String serverHostname = new String ("127.0.0.1");

        if (args.length > 0) {

//pass the hsotname through cmd argument

            serverHostname = args[0];

        }

        System.out.println ("Attemping to connect to host " + serverHostname + " on port 10007.");

        Socket echoSocket = null;

        PrintWriter out = null;

        BufferedReader in = null;

        try {

//Connect to server and open IO stream

            echoSocket = new Socket(serverHostname, 10007);

            out = new PrintWriter(echoSocket.getOutputStream(), true);

            in = new BufferedReader(new InputStreamReader(

                    echoSocket.getInputStream()));

        } catch (UnknownHostException e) {

            System.err.println("Don't know about host: " + serverHostname);

            System.exit(1);

        } catch (IOException e) {

            System.err.println("Couldn't get I/O for " + "the connection to: " +

                    serverHostname);

            System.exit(1);

        }

        BufferedReader stdIn = new BufferedReader( new InputStreamReader(System.in));

        String userInput;

        System.out.print ("input-comand: ");

        while ((userInput = stdIn.readLine()) != null) {

//send to server using socket

            out.println(userInput);

//read reply from server

            String replyFromServer = in.readLine();

            System.out.println("Answer: " + replyFromServer);

            if(replyFromServer.trim().toLowerCase().equals("bye")){

                break;

            }

            System.out.print ("input-command: ");

        }

        out.close();

        in.close();

        stdIn.close();

        echoSocket.close();

    }

}

//=================================================

import java.net.*;

import java.io.*;
import java.util.Scanner;

public class Server {

    public static void main(String[] args) throws IOException {

        ServerSocket serverSocket = null;

        try {

            serverSocket = new ServerSocket(10007);

        }

        catch (IOException e) {

            System.err.println("Could not listen on port: 10007.");

            System.exit(1);

        }

        Socket clientSocket = null;

        System.out.println ("Waiting for connection ...");

        try {

            clientSocket = serverSocket.accept();

        }

        catch (IOException e) {

            System.err.println("Accept failed.");

            System.exit(1);

        }

        System.out.println ("Connection successful");

        System.out.println ("Waiting for input ...");

//open IO streams

        PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);

        BufferedReader in = new BufferedReader(new

                InputStreamReader( clientSocket.getInputStream()));

        String inputLine;

//wait and read input from client. Exit when input from socket is Bye
        Scanner scanFile = new Scanner(new File("DNS-table.txt"));
        boolean found =false;
        while ((inputLine = in.readLine()) != null)

        {

            System.out.println ("Server: " + inputLine);
            String line ="";

            if (inputLine.trim().toLowerCase().equals("bye"))
            {
                out.println(inputLine);
                break;
            }


            while (scanFile.hasNextLine())
            {
                //reply back to client
                line  = scanFile.nextLine();
                String[] tokens = line.split(" ");
                if(inputLine.equalsIgnoreCase(tokens[0]) || inputLine.equalsIgnoreCase(tokens[1])) {
                    found = true;
                    break;
                }

                else
                    found = false;

            }
            if(found) {
                out.println(line);

            }
            else {


                out.println("Not found...");
            }
        }


//close IO streams and at the end socket
        scanFile.close();
        out.close();

        in.close();

        clientSocket.close();

        serverSocket.close();

    }

}

-------------------------------------------------------------

text

www.google.com 192.168.73.1
www.uncc.edu 192.168.73.2
www.abc.com 192.168.73.3
www.espn.com 192.168.73.4
www.cyberDNA.com 192.168.73.55
www.ccaa.uncc.edu 192.168.73.5
www.ccigrad.uncc 192.168.73.13
www.cis.uncc.edu 192.168.73.14
www.unc.edu 192.168.73.12

Answer 1

import java.net.*;

import java.io.*;
import java.util.Scanner;

public class Server {

        public static void main(String[] args) throws IOException {

                ServerSocket serverSocket = null;
                try {
                        serverSocket = new ServerSocket(10007);
                } catch (IOException e) {
                        System.err.println("Could not listen on port: 10007.");
                        System.exit(1);
                }

                while (true) {
                        Socket clientSocket = null;
                        System.out.println("Waiting for connection ...");

                        try {
                                clientSocket = serverSocket.accept();
                        } catch (IOException e) {
                                System.err.println("Accept failed.");
                                System.exit(1);
                        }

                        new ConnectionHandler(clientSocket).start();
                }

        }

        static class ConnectionHandler extends Thread {
                private Socket clientSocket;
                public ConnectionHandler(Socket clientSocket) {
                        this.clientSocket = clientSocket;
                }

                public void run() {

                        System.out.println("Connection successful");
                        System.out.println("Waiting for input ...");

                        // open IO streams
                        try {
                                PrintWriter out;
                                out = new PrintWriter(clientSocket.getOutputStream(), true);
                                BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
                                String inputLine;

                                // wait and read input from client. Exit when input from socket is Bye
                                Scanner scanFile = new Scanner(new File("DNS-table.txt"));
                                boolean found = false;
                                while ((inputLine = in.readLine()) != null)

                                {

                                        System.out.println("Server: " + inputLine);
                                        String line = "";

                                        if (inputLine.trim().toLowerCase().equals("bye")) {
                                                out.println(inputLine);
                                                break;
                                        }

                                        while (scanFile.hasNextLine()) {
                                                // reply back to client
                                                line = scanFile.nextLine();
                                                String[] tokens = line.split(" ");
                                                if (inputLine.equalsIgnoreCase(tokens[0]) || inputLine.equalsIgnoreCase(tokens[1])) {
                                                        found = true;
                                                        break;
                                                }

                                                else
                                                        found = false;

                                        }
                                        if (found) {
                                                out.println(line);

                                        } else {

                                                out.println("Not found...");
                                        }
                                }

                                // close IO streams and at the end socket
                                scanFile.close();
                                out.close();

                                in.close();

                                clientSocket.close();
                        } catch (IOException e) {
                                // TODO Auto-generated catch block
                                e.printStackTrace();
                        }
                }
        }
}

**************************************************

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