import java.io.*;
            import java.net.*;
            import java.util.*;
            import java.lang.*;
            public class Server extends ServerSocket
            {
            private static ArrayList User_List = new ArrayList();
            private static ArrayList Threader = new ArrayList();
            private static LinkedList Message_Array = new LinkedList();
            private static int Thread_Counter = 0;
            private static boolean isClear = true;
            protected static final int SERVER_PORT = 10000;
            protected FileOutputStream LOG_FILE = new FileOutputStream("d:/connect.log", true);
            public Server() throws FileNotFoundException, IOException
            {
            super(SERVER_PORT);
            new Broadcast();
            //append connection log
            Calendar now = Calendar.getInstance();
            String str = "[" + now.getTime().toString() + "] Accepted a connection\015\012";
            byte[] tmp = str.getBytes();
            LOG_FILE.write(tmp);
            try
            {
            while (true)
            {
            Socket socket = accept();
            new CreateServerThread(socket);
            }
            }
            finally
            {
            close();
            }
            }
            public static void main(String[] args) throws IOException
            {
            new Server();
            }
            //--- Broadcast
            class Broadcast extends Thread
            {
            public Broadcast()
            {
            start();
            }
            public void run()
            {
            while (true)
            {
            if (!isClear)
            {
            String tmp = (String)Message_Array.getFirst();
            for (int i = 0; i < Threader.size(); i++)
            {
            CreateServerThread client = (CreateServerThread)Threader.get(i);
            client.sendMessage(tmp);
            }
            Message_Array.removeFirst();
            isClear = Message_Array.size() > 0 ? false : true;
            }
            }
            }
            }
            //--- CreateServerThread
            class CreateServerThread extends Thread
            {
            private Socket client;
            private BufferedReader in;
            private PrintWriter out;
            private String Username;
            public CreateServerThread(Socket s) throws IOException
            {
            client = s;
            in = new BufferedReader(new InputStreamReader(client.getInputStream()));
            out = new PrintWriter(client.getOutputStream(), true);
            out.println("--- Welcome to this chatroom ---");
            out.println("Input your nickname:");
            start();
            }
            public void sendMessage(String msg)
            {
            out.println(msg);
            }
            public void run()
            {
            try
            {
            int flag = 0;
            Thread_Counter++;
            String line = in.readLine();
            while (!line.equals("bye"))
            {
            if (line.equals("l"))
            {
            out.println(listOnlineUsers());
            line = in.readLine();
            continue;
            }
            if (flag++ == 0)
            {
            Username = line;
            User_List.add(Username);
            out.println(listOnlineUsers());
            Threader.add(this);
            pushMessage("[< " + Username + " come on in >]");
            }
            else
            {
            pushMessage("<" + Username + ">" + line);
            }
            line = in.readLine();
            }
            out.println("--- See you, bye! ---");
            client.close();
            }
            catch (IOException e)
            {}
            finally
            {
            try
            {
            client.close();
            }
            catch (IOException e)
            {}
            Thread_Counter--;
            Threader.remove(this);
            User_List.remove(Username);
            pushMessage("[< " + Username + " left>]");
            }
            }
            private String listOnlineUsers()
            {
            String s ="-+- Online list -+-\015\012";
            for (int i = 0; i < User_List.size(); i++)
            {
            s += "[" + User_List.get(i) + "]\015\012";
            }
            s += "-+---------------------+-";
            return s;
            }
            private void pushMessage(String msg)
            {
            Message_Array.addLast(msg);
            isClear = false;
            }
            }
            }