java客户端登陆服务器用户名验证

import java.io.*; 
import java.net.*; 
/* 
*客户端 
*/ 
class client 
{ 
 public static void main(String[] args) throws Exception 
 { 
  Socket s = new Socket("192.168.33.1",10008);//建立服务 
  BufferedReader bufr = new BufferedReader(new InputStreamReader(System.in));//读取键盘输入用户名 
  PrintWriter pw = new PrintWriter(s.getOutputStream(),true);//读到数据往服务端写 
  BufferedReader bufin = 
   new BufferedReader(new InputStreamReader(s.getInputStream()));//将客户端返回的数据读入 
  for(int x = 0;x <3; x ++)//只登陆3次设定 
  { 
   String line = bufr.readLine();//读取用户名 
   pw.println(line); 
   if(line == null)//为空用户名终止 
    break; 
   pw.println(line); 
   String info = bufin.readLine();//读取服务端返回的数据 
   System.out.println("Server info:"+info); 
   if(info.contains("欢迎登陆"))//用户登录终止 
    break; 
  } 
  bufr.close(); 
  s.close(); 
 } 
} 
/* 
*服务端 
*/ 
class ServerThread implements Runnable 
{ 
 private Socket s; 
 ServerThread(Socket s) 
 { 
  this.s = s; 
 } 
 public void run() 
 { 
  String ip = s.getInetAddress().getHostAddress(); 
  System.out.println(ip+"...........connect"); 
  try 
  { 
   for(int x = 0;x <3;x ++) 
   { 
    BufferedReader bufin = new BufferedReader(new InputStreamReader(s.getInputStream()));//读取客户端发送的数据 
    String name = bufin.readLine(); 
    if(name == null) 
     break; 
    BufferedReader bufr = new BufferedReader(new FileReader("user.txt"));//读取已存入用户账户，本来是读取数据库，这里方便就写了一个文本 
    PrintWriter out = new PrintWriter(s.getOutputStream(),true);//写入流，服务端写出 
    String line = null; 
    boolean flag = false;//判断标记 
    while((line = bufr.readLine())!= null)//读取数据库(Use.txt)中数据 
    { 
     if(line.equals(name))//如果数据库和读取用户名相同，则终止 
     { 
      flag = true; 
      break; 
     } 
    } 
    if(flag) 
     { 
      System.out.println(name+":已登录"); 
      out.println(name+":欢迎登陆"); 
      break; 
     } 
    else 
    { 
     System.out.println(name+":尝试登陆"); 
     out.println(name+":用户名不存在"); 
    } 
   } 
   s.close(); 
  } 
  catch (Exception e) 
  { 
   throw new RuntimeException("验证失败"); 
  } 
 } 
} 
class server 
{ 
 public static void main(String[] args) throws Exception 
 { 
  ServerSocket ss = new ServerSocket(10008);//建立服务 
  while (true) 
  { 
   Socket s = ss.accept();//接收客户端传来数据 
   new Thread(new ServerThread(s)).start();//开启线程 
  } 
 } 
}