Socket : MultiClient Server

Hello,

I need to make following server in to MultiClient. I'm new in JAVA, so I can not figure it out. I don't even know if it's possible to make it in any easy way, because I tried to look for any possible information or help and I failed, so, if it's not too complicated, if anyone can help to me?
This server is not written by me, I took it from JAVA SUN page.

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

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

ServerSocket serverSocket = null;
        try {
            serverSocket = new ServerSocket(4444);
        } catch (IOException e) {
            System.err.println("Could not listen on port: 4444.");
            System.exit(1);
        }

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

PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);
        BufferedReader in = new BufferedReader(
                new InputStreamReader(
                clientSocket.getInputStream()));
        String inputLine, outputLine;
        KnockKnockProtocol kkp = new KnockKnockProtocol();

outputLine = kkp.processInput(null);
        out.println(outputLine);

while ((inputLine = in.readLine()) != null) {
             outputLine = kkp.processInput(inputLine);
             out.println(outputLine);
             if (outputLine.equals("Bye."))
                break;
        }
        out.close();
        in.close();
        clientSocket.close();
        serverSocket.close();
    }
}

Hi karl, the below program will help you much.

Server:
public class TCPServer{
private ServerSocket server;
private int port = 7777;

public TCPServer() {
try {
server = new ServerSocket(port);
} catch (IOException e) {
e.printStackTrace();
}
}

public static void main(String[] args) {
TCPServer example = new TCPServer();
example.handleConnection();
}

public void handleConnection() {
System.out.println("Waiting for client message...");

while (true) {
try {
Socket socket = server.accept();
ConnectionHandler cd = new ConnectionHandler(socket);
} catch (IOException e) {
e.printStackTrace();
}
}
}
}

for each client separate Thread will be created

Thread Class: ConnectionHandler

class ConnectionHandler implements Runnable {
private Socket theclient;
ServerSocket serverSocket = null;

public ConnectionHandler(Socket theclient) {
this.theclient = theclient;

Thread t = new Thread(this);
t.start();
}

public void run() {
try
{
PrintWriter out = new PrintWriter(theclient.getOutputStream(),true);
BufferedReader in = new BufferedReader(new InputStreamReader(theclient.getInputStream()));
BufferedReader input = new BufferedReader(new InputStreamReader(System.in));

String inputLine, outputLine;
while((inputLine=in.readLine()) != null) {
out.println();

System.out.println("From Client:"+inputLine);
outputLine=input.readLine();
out.println(outputLine);

if (inputLine.equals("Bye"))
break;
}
out.flush();

out.close();
in.close();
theclient.close();
serverSocket.close();

} catch (IOException e) {
e.printStackTrace();
}
}
}

Client:

public class TCPClient {
public static Socket clientSocket = null;
public static PrintWriter out = null;
public static BufferedReader in = null;
public static int port=0;
static InetAddress mcAddress=null;

public static void main(String[] args) {
try
{
mcAddress = InetAddress.getByName("228.1.2.3");
port = Integer.parseInt("7777");
clientSocket = new Socket("localhost", port);
out = new PrintWriter(clientSocket.getOutputStream(), true);

in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
BufferedReader input = new BufferedReader(new InputStreamReader(System.in));

String userInput;
String inetAddress = clientSocket.getInetAddress().getHostName();
out.println(inetAddress);
while((userInput = input.readLine())!= null)
{
out.println(userInput);
System.out.println("From Server: "+ in.readLine());
out.flush();
}

out.close();
in.close();
input.close();
clientSocket.close();
}
catch (IOException e) {
e.printStackTrace();
}
}
}

-Prabhakaran

Both these codes suffer from a fundamental flaw: Don't println to a Socket

Thank you, Prabhakaran, this is really useful!!