给大家分享一段验证码生成的代码 - 黑马程序员技术交流社区

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Panel;
import java.util.Random;
import javax.swing.JFrame;
/**
* 验证码Demo
* @author Shawn·Zhang
*
*/
public class Code {
public static void main(String[] args) {
final JFrame frame = new JFrame("验证码");
final Panel panel = new CodePanel();
frame.add(panel);
frame.setSize(180,85);
//frame.setSize(160, 40);//取消边框，大小可设置成画布大小
frame.setLocationRelativeTo(null);//窗口居中
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//frame.setUndecorated(true);//可设置取消窗口
frame.setVisible(true);
}
}
class CodePanel extends Panel{
public void paint(Graphics g) {
//定义大小
int width = 160;
int height = 40;
//定义背景
g.setColor(Color.LIGHT_GRAY);
g.fillRect(0, 0, width, height);
//定义边框
g.setColor(Color.BLACK);
g.drawRect(0, 0, width-1, height-1);
//随机颗粒
Random r = new Random();
for(int i=0; i<100; i++){
int x = r.nextInt(width)-2;
int y = r.nextInt(height)-2;
g.drawOval(x, y, 2, 2);
}
//定义字体
g.setFont(new Font("黑体",Font.BOLD,30));
g.setColor(Color.GREEN);
StringBuilder sb = new StringBuilder();
for(int i=0; i<4; i++){
char[] chs = ("0123456789qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM").toCharArray();
int pos = r.nextInt(chs.length);
char c = chs[pos];
sb.append(c+" ");
}
//写入验证码
g.drawString(sb.toString(), 20, 30);
}
}

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