JAVA--生成验证码

import java.awt.Color;

import java.awt.Font;

import java.awt.Graphics;

import java.awt.Image;

import java.awt.image.BufferedImage;

import java.util.Random;

import javax.swing.JFrame;

import javax.swing.JPanel;

public class CodeMatch extends JFrame{

   

    

    public CodeMatch(){

        

    }

    

    public static void main(String[] args){

        int width = 100;

        int height = 40;

        BufferedImage img = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);

        Graphics g = img.getGraphics();

        g.setColor(new Color(100,100,100));

        g.fillRect(0,0,width,height);

        Random md = new Random();

        int randnum = md.nextInt(9000)+1000;

        String randstr = String.valueOf(randnum);

        g.setColor(Color.BLACK);

        g.setFont(new Font("",Font.PLAIN,20));

        g.drawString(randstr,30, 30);

        for(int i=0;i<100;i++){

            int x = md.nextInt(width);

            int y = md.nextInt(height);

            g.drawOval(x,y,1,1);

            

        }

        

        Image image = (Image)img;

       Panel pane = new Panel(image);

        

        JFrame frame = new JFrame();

        frame.add(pane);

        frame.setSize(100,70);

        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        frame.setLocationRelativeTo(null);

        frame.setVisible(true);

    }

}

class Panel extends JPanel{

    Image img;

    public Panel(Image img){

        this.img = img;

        repaint();

    }

    

    protected void paintComponent(Graphics g) {

        super.paintComponent(g);

        g.drawImage(img, 0, 0, getWidth(), getHeight(), this);

    }

}