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SpringBoot后端验证码-防止密码爆破功能

news 2025/8/2 23:10:09

一、简介

为了防止网站的用户被通过密码典爆破。引入验证码的功能是十分有必要的。而前端的验证码又仅仅是只防君子不防小人。通过burpsuit等工具很容易就会被绕过。所以后端实现的验证码才是对用户信息安全的一大重要保障。

实现思路：

1.引入图形生成的依赖

2.生成随机4字符，并制作成图片

3.对图片进行Base64形式数据进行传输

4.前端显示

二、引入依赖

<!--        验证码模块-->
<dependency><groupId>org.apache.commons</groupId><artifactId>commons-lang3</artifactId><version>3.12.0</version>
</dependency>

三、验证码生成工具类

public class CaptchaUtil {private static final int WIDTH = 200;private static final int HEIGHT = 75;private static final int FONT_SIZE = 36;private static final String DEFAULT_FONT = "Arial";/*** 生成验证码图像.** @param captchaText 验证码原始文本* @return Base64编码的图像字符串*/public static String generateCaptchaImage(String captchaText) {if (captchaText == null || captchaText.isEmpty()) {throw new IllegalArgumentException("Captcha text cannot be null or empty.");}// 创建图像和图形上下文BufferedImage image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);Graphics2D g = (Graphics2D) image.getGraphics();// 设置背景颜色g.setColor(Color.WHITE);g.fillRect(0, 0, WIDTH, HEIGHT);// 绘制验证码文本g.setFont(new Font(DEFAULT_FONT, Font.BOLD, FONT_SIZE));g.setColor(getRandomColor());g.drawString(captchaText, 45, 50);// 添加随机线条作为干扰addNoiseLines(g);// 关闭图形上下文g.dispose();// 将图像转换为Base64编码的字符串try (ByteArrayOutputStream baos = new ByteArrayOutputStream()) {ImageIO.write(image, "png", baos);return Base64.getEncoder().encodeToString(baos.toByteArray());} catch (Exception e) {throw new RuntimeException("Error generating captcha image", e);}}private static void addNoiseLines(Graphics2D g) {for (int i = 0; i < 5; i++) {g.setColor(getRandomColor());g.drawLine(getRandomNumber(WIDTH),getRandomNumber(HEIGHT),getRandomNumber(WIDTH),getRandomNumber(HEIGHT));}}private static Color getRandomColor() {return new Color((int) (Math.random() * 255),(int) (Math.random() * 255),(int) (Math.random() * 255));}private static int getRandomNumber(int bound) {return (int) (Math.random() * bound);}
}

四、通过Http Session存放验证码与验证

获取(a-z A-Z 0-9)随机四位的验证码功能：

  // 登陆时候获取验证码@ApiOperation("获取验证码功能")@GetMapping("/GetCaptcha")public String GetCaptcha(HttpSession session) {//        随机生成四位验证码原始数据String allowedChars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";String randomString = generateRandomString(allowedChars, 4);System.out.println("captchaCode " + randomString);// 将验证码保存到session中session.setAttribute("captcha", randomString); // 使用方法参数sessionString ImageByBase64 = CaptchaUtil.generateCaptchaImage(randomString);return ImageByBase64;}

用户登陆时候校验验证码功能：

// 实现登陆功能@ApiOperation("用户登陆功能")@PostMapping("/login")public Result Login(@RequestBody LoginDTO loginDTO, HttpSession session) { // 使用同一个HttpSession参数String captcha = (String) session.getAttribute("captcha");log.info("用户调用login方法");if (loginDTO.getCaptcha() == null || !loginDTO.getCaptcha().equalsIgnoreCase(captcha)) {session.removeAttribute("captcha");return Result.error("验证码出错了噢!");}// 对密码进行md5加密String encryptToMD5 = MD5Util.encryptToMD5(loginDTO.getPassword());LambdaQueryWrapper<User> lambdaQueryWrapper = new LambdaQueryWrapper<>();lambdaQueryWrapper.eq(User::getAccount, loginDTO.getAccount()).eq(User::getPassword, encryptToMD5);User user = userService.getOne(lambdaQueryWrapper);if (user == null) {return Result.error("很抱歉，查不到此用户");}user.setPassword("xxxxx");return Result.success(user);}

五、前端显示Base64格式的图片

前端实现注册的表单

<el-tab-pane label="登陆" name="first"><el-form :model="loginForm" ref="loginFormRef" label-width="80px"><el-form-item label="用户名:"><el-input v-model="loginForm.account"></el-input></el-form-item><el-form-item label="密码:"><el-input v-model="loginForm.password" show-password></el-input></el-form-item><el-form-item label="验证码"><el-input v-model="loginForm.captcha" style="width: 20%;"></el-input><img :src="captchaImageUrl" alt="验证码" @click="refreshCaptcha" id="captchaImage"></el-form-item></el-form></el-tab-pane>

先设置为空

export default {data() {return {captchaImageUrl: '', // 初始化为一个空字符串}},

在点击登陆按钮后，执行getCaptcha函数并设置captchaImageUrl的回显格式为Base64

  fetchCaptcha() {axios.get('/api/user/GetCaptcha').then(response => {this.captchaImageUrl = 'data:image/png;base64,' + response.data;}).catch(error => {console.error('获取验证码失败:', error);});},

最后进行测试：