TCPServer.java

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;

public class TCPServer {

    private static Thread threadClients;
    private static Thread threadWriteToClients;
    private static Thread threadServerCommands;
    private static ServerSocket welcomeSocket;
    private static List<Socket> clientsArray = new ArrayList<Socket>();
    private static boolean go_on = true;
    private static String sentence;
    private static String serverCMD;
    private static BufferedReader inFromClient;
    private static Socket connectionSocket;
    private static DataOutputStream outToClient;

     public static void main(String argv[]) throws Exception
     {
         System.out.println("starting main");
         welcomeSocket = new ServerSocket(9876);
         System.out.println("Server socket klar");



         // Laver sockets til hver enkel Client (accepterer)
         threadClients = new Thread(new Runnable() {
                public void run() {
                    while(go_on) {
                        try {
                            connectionSocket = welcomeSocket.accept();
                            inFromClient = new BufferedReader(new InputStreamReader(connectionSocket.getInputStream()));
                            clientsArray.add(connectionSocket);
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                }
            });
         threadClients.start();



      // Traad til at skrive til samtlige clients
         threadWriteToClients = new Thread(new Runnable() {
                public void run() {
                    while(go_on) {
                        try {
                            connectionSocket = welcomeSocket.accept();
                            sentence = inFromClient.readLine();
                            for (int i = 0; i < clientsArray.size(); i++) {
                                outToClient = new DataOutputStream(clientsArray.get(i).getOutputStream());
                                outToClient.writeBytes("FROM SOME CLIENT: " + sentence + "\n");
                            }

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

                    }
                }
            });
         threadWriteToClients.start();



      // SERVER kommandoer (gaar ogsaa ud til clients)
         threadServerCommands = new Thread(new Runnable() {
                public void run() {
                    BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in));
                    while(go_on) {
                        try {
                            serverCMD = inFromUser.readLine();
                            for (int i = 0; i <= clientsArray.size(); i++) {
                                outToClient = new DataOutputStream(clientsArray.get(i).getOutputStream());
                                outToClient.writeBytes(serverCMD + "\n");
                            }

                            if (serverCMD.equals("quit")) {
                                go_on = false;
                                System.out.println("quitting the loop and closing the socket");
                                connectionSocket.close();
                                welcomeSocket.close();
                            }

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

                    }
                }
            });
         threadServerCommands.start();


        }

}