ChatServer.java

package clientServer;
import java.net.*;
import java.io.*;

public class ChatServer implements Runnable
{  private ChatServerThread clients[] = new ChatServerThread[50];
    private ServerSocket server = null;
    private Thread       thread = null;
    private int clientCount = 0;
    
    public ChatServer(int port)
    {  try
        {  System.out.println("Binding to port " + port + ", please wait  ...");
            server = new ServerSocket(port);
            System.out.println("Server started: " + server);
            start();
        }
        catch(IOException ioe)
        {  System.out.println("Can not bind to port " + port + ": " + ioe.getMessage()); }
    }
    
    public void run()
    {  while (thread != null)
        {  try
            {  System.out.println("Waiting for a client ...");
                addThread(server.accept());
            }
            catch(IOException ioe)
            {  System.out.println("Server accept error: " + ioe); 
            	stop(); 
            }
        }
    }
    
    public void start(){
        if (thread == null){
            thread = new Thread(this);
            thread.start();
        }
    }
    
    public void stop()
    {  if (thread != null)
        {  thread.stop();
           thread = null;
        }
    }
    
    private int findClient(int ID)
    {  for (int i = 0; i < clientCount; i++)
        if (clients[i].getID() == ID) return i;
        return -1;
    }
    
    public synchronized void handle(int ID, String input){
        if(input.equals(".bye")){
            clients[findClient(ID)].send(".bye");
            remove(ID);
        }
    else
        for (int i = 0; i < clientCount; i++)
            clients[i].send(ID + ": " + input);
    }
    
    public synchronized void remove(int ID){
        int pos = findClient(ID);
        if (pos >= 0)
        {   ChatServerThread toTerminate = clients[pos];
            System.out.println("Removing client thread " + ID + " at " + pos);
            if (pos < clientCount-1){
                for (int i = pos+1; i < clientCount; i++)
                    clients[i-1] = clients[i];
            }
            clientCount--;
            try
            {  toTerminate.close(); }
            catch(IOException ioe)
            {  System.out.println("Error closing thread: " + ioe); }
            toTerminate.stop();
        }
    }
    
    //add a new client that try to connect to server
    private void addThread(Socket socket)
    {
        if (clientCount < clients.length)
        {
            System.out.println("Client accepted: " + socket);
            clients[clientCount] = new ChatServerThread(this, socket);
            try
            {   clients[clientCount].open();
                clients[clientCount].start();
                clientCount++;
            }
            catch(IOException ioe)
            { System.out.println("Error opening thread: " + ioe); } }
       else
       {System.out.println("Client refused: maximum " + clients.length + " reached.");}
    }
            
    public static void main(String args[]){
    	
        ChatServer server = null;
        /*
        if (args.length != 1)
        System.out.println("Usage: java ChatServer port");
        else server = new ChatServer(Integer.parseInt(args[0]));
        */
        server = new ChatServer(4444);
    }
}