자바로 작성하는 기초 채팅 프로그램(서버)

import java.net.*;
import java.util.*;

class ChatServer {
	ServerSocket ss;
	Vector<ChatHandler> v = new Vector<ChatHandler>();

	public ChatServer() {
		try {
			ss = new ServerSocket(9500);
			System.out.println("서버준비완료...");
			while (true) {
				Socket so = ss.accept();// 클라이어트를 낚아챈다
				ChatHandler ch = new ChatHandler(this, so);
				ch.start();
			}
		} catch (java.io.IOException io) {
			io.printStackTrace();
		}
	}

	public void register(ChatHandler ch) {
		v.add(ch);
	}

	public void unregister(ChatHandler ch) {
		v.remove(ch);
	}

	public void broadcast(String msg) {
		Iterator<ChatHandler> it = v.iterator();
		while (it.hasNext()) {
			// ChatHandler ch = (ChatHandler)it.next();
			ChatHandler ch = it.next();
			ch.getPrintWriter().println(msg);
			ch.getPrintWriter().flush();
		}
	}

	public static void main(String[] args) {
		new ChatServer();
	}
}