线程登陆，限定只能3次

//package com.org.Net.tcp;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;

class LoginClient {

	public static void main(String[] args) throws Exception {

		Socket s = new Socket("192.128.11.103", 11110);

		BufferedReader buf = new BufferedReader(
				new InputStreamReader(System.in));

		PrintWriter out = new PrintWriter(s.getOutputStream(), true);
		BufferedReader bufIn = new BufferedReader(new InputStreamReader(s.getInputStream()));

		for (int i = 0; i < 3; i++) {
			String line = buf.readLine();
			if (line == null)
				break;
			out.println(line);
			String info = bufIn.readLine();
			System.out.println("Info"+info);
			
			if(info.contains("欢迎~"))
				break;
		}
		buf.close();
		bufIn.close();

	}
}

class UserThread implements Runnable {
	private Socket s;

	UserThread(Socket s) {
		this.s = s;
	}

	@Override
	public void run() {
		
		String ip=s.getInetAddress().getHostName();
		
		System.out.println(ip);
		try {
			for (int i = 0; i < 3; i++) {

				BufferedReader bufIn = new BufferedReader(
						new InputStreamReader(s.getInputStream()));
				String name = bufIn.readLine();// name
				BufferedReader bufr = new BufferedReader(new FileReader(
						"user.txt"));
				
				PrintWriter out=new PrintWriter(s.getOutputStream(),true);
				String line = null;
				boolean flag = false;
				while ((line = bufr.readLine()) != null) {
					if (line.equals(name)) {
						flag = true;
						break;
					} 
				}
				if(flag){
					
					System.out.println(name+"已登录");
					out.println(name+"欢迎光临");
				}else {

					System.out.println(name+"不存在!");
					out.println(name+"欢迎光临");
					
				}
			}
			s.close();
		} catch (Exception e) {
			throw new RuntimeException("校正失败!");
		}
	}

}

class LoginServer {

	public static void main(String[] args) throws Exception {
		ServerSocket ss = new ServerSocket(11110);

		while (true) {

			Socket s = ss.accept();
			new Thread(new UserThread(s)).start();
		}
	}

}