java 实现的端口扫描器

import java.net.*;
import java.io.*;
public class PortScanner {
    public static void main(String args[]){
    String host="localhost";
    new PortScanner().scan(host);
    }
    public void scan(String host){
    Socket socket=null;
    System.out.println("scanning...");
    for(int port=1;port<65535;port++){
       try {
     //socket=new Socket(host,port);
        socket=new Socket();
        SocketAddress remoteAddr=new InetSocketAddress(host,port);
        socket.connect(remoteAddr,1);//超时时间1ms
     System.out.println("there is a server on port "+port);
   
       } catch (UnknownHostException e) {
    
     e.printStackTrace();
    } catch (IOException e) {
     //System.out.println("connot connect to port"+port);
    }finally{
     if(socket!=null){
      try {
       socket.close();
      } catch (IOException e) {
      
       e.printStackTrace();
      }
     }
    }
      
    }
    System.out.println("scan over.");
    }
   
}