多client并发登录

//LoginClient.java

package mySocket;

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


/**
 *client通过键盘录入username
 *服务端对这个username进行校验。
 *
 *假设该用户存在，在服务端显示xxx,已登录。
 *并在client显示xxx,欢迎光临。

 *
 *假设该用户存在，在服务端显示xxx。尝试登陆。
 *并在client显示xxx,该用户不存在。
 *
 *最多登陆3次。
 */
public class LoginClient {

	public static void main(String[] args) throws  Exception {
			Socket s = new Socket("192.168.1.103",10008);
			
			BufferedReader bufr = 
					new BufferedReader(new InputStreamReader(System.in));
			
			PrintWriter out = new PrintWriter(s.getOutputStream(),true);
			
			BufferedReader bufIn = 
					new BufferedReader(new InputStreamReader(s.getInputStream()));
			
			for(int x=0;x<3;x++)	{
				//读键盘
				String line = bufr.readLine();
				if(line==null)
					break;
				//发出去
				out.println(line);
				//读取服务端反馈				
				String info = bufIn.readLine();
				System.out.println(info);
				if(info.contains("欢迎"))
					break;
			}
			bufr.close();
			s.close();

	}

}

//LoginServer.java

package mySocket;

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


class LoginThread implements Runnable	{
		private Socket s; 
		public LoginThread(Socket s) {
			this.s = s;
		}
		public void run() {
			//获取连接的ip
			String ip = s.getInetAddress().getHostAddress();
			System.out.println(ip+"已被连接");
			
			try {
					for(int x=0;x<3;x++)	{
							BufferedReader bufIn =
									new BufferedReader(new InputStreamReader(s.getInputStream()));
							//读取client发来的数据
							String name = bufIn.readLine();
							if(name==null)
								break;
							//读取user.txt里的数据
							BufferedReader bufr = 
									new BufferedReader(new FileReader("user.txt"));
							
							String line = null;
							boolean flag = false;
							
							while((line=bufr.readLine())!=null)	{
									if(line.equals(name))	{
										flag = true;
										break;
									}
							}
							
							PrintStream out = new PrintStream(s.getOutputStream(),true);
							if(flag)	{
								System.out.println(name+"已登录");
								 out.println(name+"欢迎光临");
								 break;
							}
							else{
								System.out.println(name+"尝试登陆");
								out.println(name+"username不存在");
							}
							
							s.close();
					}
			} catch (Exception e) {
						throw new RuntimeException(ip+"校验失败");
			}
		}
}

public class LoginServer {

	public static void main(String[] args) throws Exception {
			ServerSocket ss = new ServerSocket(10008);
			
			while(true)	{
				Socket s = ss.accept();
				new Thread(new LoginThread(s)).start();
			}
	}

}

//学习自毕向东老师培训视频