package Main;

import javax.swing.*;
import java.awt.*;
import java.util.Random;

/**
 * @version 1.0
 * @author DGW-PC
 */
public class Main extends JFrame{

 Main(){
 setSize(400,100);
 setLocationRelativeTo(null);
 add(new myVerification());
 setVisible(true);
 }

 public static void main(String[] args) {
 new Main();
 }

}

class myVerification extends JPanel{

 public static final int WIDTH=200;
 public static final int HEIGTH=300;

 @Override
 public void paint(Graphics g) {
 g.setColor(Color.lightGray);
 g.fillRect(0,0,WIDTH, HEIGTH);
 g.setColor(Color.BLACK);
 g.drawRect(0,0,WIDTH-1,HEIGTH-1);
 Random random = new Random();
 for (int i = 0; i < 100; i++) {
 int x=random.nextInt(WIDTH)-2;
 int y=random.nextInt(HEIGTH)-2;
 g.drawOval(x,y,2,2);
 }
 g.setFont(new Font("黑体",Font.BOLD,60));
 g.setColor(Color.black);
 char[] chars = ".abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ".toCharArray();
 StringBuffer b = new StringBuffer();
 for (int i = 0; i < 4; i++) {
 int i1 = random.nextInt(chars.length);
 char c = chars[i1];
 b.append(c + "");
 }
 g.drawString(b.toString(),30,40);
 }
}