import java.io.*; import java.net.*; /* *客戶端 */ class client {  public static void main(String[] args) throws Exception  {   Socket s = new Socket("192.168.33.1",10008);//建立服務   BufferedReader bufr = new BufferedReader(new InputStreamReader(System.in));//讀取鍵盤輸入用戶名   PrintWriter pw = new PrintWriter(s.getOutputStream(),true);//讀到數據往服務端寫   BufferedReader bufin =    new BufferedReader(new InputStreamReader(s.getInputStream()));//將客戶端返回的數據讀入   for(int x = 0;x < 3; x ++)//只登陸3次設定   {    String line = bufr.readLine();//讀取用戶名    pw.println(line);    if(line == null)//為空用戶名終止     break;    pw.println(line);    String info = bufin.readLine();//讀取服務端返回的數據    System.out.println("Server info:"+info);    if(info.contains("歡迎登陸"))//用戶登錄終止     break;   }   bufr.close();   s.close();  } } /* *服務端 */ 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()));//讀取客戶端發送的數據     String name = bufin.readLine();     if(name == null)      break;     BufferedReader bufr = new BufferedReader(new FileReader("user.txt"));//讀取已存入用戶賬戶，本來是讀取數據庫，這里方便就寫了一個文本     PrintWriter out = new PrintWriter(s.getOutputStream(),true);//寫入流，服務端寫出     String line = null;     boolean flag = false;//判斷標記     while((line = bufr.readLine())!= null)//讀取數據庫(Use.txt)中數據     {      if(line.equals(name))//如果數據庫和讀取用戶名相同，則終止      {       flag = true;       break;      }     }     if(flag)      {       System.out.println(name+":已登錄");       out.println(name+":歡迎登陸");       break;      }     else     {      System.out.println(name+":嘗試登陸");      out.println(name+":用戶名不存在");     }    }    s.close();   }   catch (Exception e)   {    throw new RuntimeException("驗證失敗");   }  } } class server {  public static void main(String[] args) throws Exception  {   ServerSocket ss = new ServerSocket(10008);//建立服務   while (true)   {    Socket s = ss.accept();//接收客戶端傳來數據    new Thread(new ServerThread(s)).start();//開啟線程   }  } }