SpringBoot 图片验证码生成工具、直接上干货

定义CaptchaUtil工具类

package vip.appdesign.suncms.common.utils;


import java.awt.*;
import java.awt.image.BufferedImage;
import java.util.Random;

/**
 * 验证码生成工具
 * @author sun
 * @date 2025/7/8
 */

public class CaptchaUtil {
    static Random rand = new Random();
    /**
     * 获取随机字符串
     * @param length 获取字符长度
     * @return 随机字符串
     */

    public static String getRandString(Integer length) {
        String chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
        Random random = new Random();
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < length; i++) {
            sb.append(chars.charAt(rand.nextInt(chars.length())));
        }
        return sb.toString();
    }
    // 生成随机颜色
    public static Color getColor() {
        return new Color(rand.nextInt(256), rand.nextInt(256), rand.nextInt(256));
    }

    /**
     * 获取验证码
     * @param randomString 随机字符串
     * @return BufferedImage
     */
    public static BufferedImage getCaptcha(String randomString) {
        BufferedImage image = new BufferedImage(160, 60, BufferedImage.TYPE_INT_RGB);
        Graphics graphics = image.getGraphics();
        graphics.fillRect(0, 0, image.getWidth(), image.getHeight());
        graphics.setColor(Color.BLACK);
        //绘制干扰线
        for (int i = 0; i < 200; i++) {
            int x = rand.nextInt(image.getWidth());
            int y = rand.nextInt(image.getHeight());
            int x1 = rand.nextInt(x+10);
            int y1 = rand.nextInt(y+10);
            graphics.setColor(getColor());
            graphics.drawLine(x, y, x, y);//参数3和4填写x1,y1可以增加干扰程度
        }
        graphics.setFont(new Font("Times New Roman", Font.BOLD, 30));
        graphics.drawString(randomString + "", 60, 40);
        return image;

    }
}

对应Controller控制内写法

@RestController
@RequestMapping("/auth")
public class AuthController {
    @GetMapping("/captcha")
    public void getCapcha(HttpServletRequest request, HttpServletResponse response) throws IOException {
        //生成验证码
        String captcha = CaptchaUtil.getRandString(4);
        //验证码存储到session中
        request.getSession().setAttribute("captcha", captcha.toLowerCase());
        //生成验证码图片
        BufferedImage bufferedImage = CaptchaUtil.getCaptcha(captcha);
        //设置响应头
        response.setContentType("image/png");
        response.setHeader("Cache-Control", "no-cache");
        response.setHeader("Pragma", "No-cache");
        response.setDateHeader("Expires", 0);
        ImageIO.write(bufferedImage,"png",response.getOutputStream());

    }
}

//生成图片截图案例