import javax.swing.*;

import java.awt.Dimension;

import java.awt.Font;

import java.awt.Toolkit;

import java.awt.event.*;

public class PortScan extends JFrame {

    JPanel center=new JPanel();

    Box hBox0=Box.createHorizontalBox();

     Box hBox1= Box.createHorizontalBox();

     Box hBox2= Box.createHorizontalBox();

     Box hBox3= Box.createHorizontalBox();

    private JLabel state=new JLabel("关闭");

    private JLabel HOST=new JLabel("主机名:");

    private JLabel PORT=new JLabel("端口号:");

    private JLabel STATE=new JLabel("状态：");

    private JButton btn1=new JButton("开始扫描");

    private JButton reset=new JButton("重置");

    private JTextField host=new JTextField(20);

    private JTextField port=new JTextField(7);

    Font f1=new Font("隶书",Font.PLAIN,15);

    public static void main(String[] args) {

        JFrame portscan=new PortScan();

        portscan.setVisible(true);

    }

    public PortScan(){

        setTitle("PortScanner");

        setSize(300, 200);

        center.setLayout(new BoxLayout(center,BoxLayout.Y_AXIS));

         Toolkit kit = Toolkit.getDefaultToolkit();

            Dimension screenSize = kit.getScreenSize();//获取屏幕分辨率

          setLocation(screenSize.width/4,screenSize.height/4);//位置

          state.setFont(f1);

          HOST.setFont(f1);

          PORT.setFont(f1);

          btn1.setFont(f1);

          reset.setFont(f1);

          STATE.setFont(f1);

         center.add(hBox0);

         center.add(Box.createRigidArea(new Dimension(10,20)));

         center.add(hBox1);

         center.add(Box.createRigidArea(new Dimension(2,20)));

         center.add(hBox2);

         center.add(Box.createRigidArea(new Dimension(2,20)));

         center.add(hBox3);

         hBox0.add(HOST);

         hBox0.add(host);

         hBox1.add(PORT);

         hBox1.add(port);

         hBox2.add(btn1);

         hBox2.add(reset);

         hBox3.add(STATE);

         hBox3.add(state);

         add(center);

         btn1.addActionListener(new MyActionListener());

         reset.addActionListener(new MyActionListener());

    }

    class MyActionListener implements ActionListener{

        @Override

        public void actionPerformed(ActionEvent e) {

            String post1=host.getText();

            int port1=Integer.parseInt(port.getText());

            if(e.getActionCommand()=="开始扫描"){

            if(    PortScannerByIP.scan(post1, port1)){

                state.setText("开放");

            }else{

                state.setText("关闭");

            }

            }

            if(e.getActionCommand()=="重置"){

                host.setText("");

                port.setText("");

            }

        }

    }

}

import java.io.IOException;

import java.net.Socket;

public class PortScannerByIP {

    public static boolean scan(String host,int port){

        boolean flag=true;

        Socket socket=null;

        try {

            socket=new Socket(host,port);

            return flag;

        } catch (IOException e) {

            flag=false;

            return flag;

        }finally{

            try {

                if(socket!=null)

                    socket.close();

            } catch (IOException e) {

                e.printStackTrace();

            }

        }

    }

}