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1、导入Kaptcha依赖支持

<dependency>    <groupId>com.github.penggle</groupId>    <artifactId>kaptcha</artifactId>    <version>2.3.2</version></dependency>

 2、编写实现验证码功能的实现类

//实现验证码功能配置类@Configurationpublic class KaptchaConfig {    private final static String CODE_LENGTH = "4";    @Bean    public Producer kaptchaProducer() {        Properties properties = new Properties();        // 设置边框        properties.setProperty("kaptcha.border", "yes");        // 设置边框颜色        properties.setProperty("kaptcha.border.color", "105,179,90");        // 设置字体颜色        properties.setProperty("kaptcha.textproducer.font.color", "0,153,153");        // 设置图片宽度        properties.setProperty("kaptcha.image.width", "118");        // 设置图片高度        properties.setProperty("kaptcha.image.height", "36");        // 设置字体尺寸        properties.setProperty("kaptcha.textproducer.font.size", "30");        // 设置字体        properties.setProperty("kaptcha.textproducer.font.names", "Blackletter,Hakuu,Tahoma");        //        properties.setProperty("kaptcha.background.clear.from","153,255,204");        //        properties.setProperty("kaptcha.background.clear.to","153,204,153");        // 验证码字符串        properties.setProperty("kaptcha.textproducer.char.string", "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYAZ");        // 设置验证码长度        properties.setProperty("kaptcha.textproducer.char.length", CODE_LENGTH);        // 图片干扰线：无干扰线        properties.setProperty("kaptcha.noise.impl", "com.google.code.kaptcha.impl.NoNoise");        DefaultKaptcha kaptcha = new DefaultKaptcha();        Config config = new Config(properties);        kaptcha.setConfig(config);        return kaptcha;    }}

3、编写Controller类调用验证码功能

/*    单体应用项目*/ @Autowired    private Producer kaptchaProducer;    @GetMapping("/kaptcha")    public void getKaptcha(HttpServletRequest req, HttpServletResponse resp){        //生成验证码        String text = kaptchaProducer.createText();        BufferedImage image = kaptchaProducer.createImage(text);        //将验证码存放在session中        req.getSession().setAttribute("kaptcha",text);        //将图片输出给浏览器        resp.setContentType("image/png");        try {            ServletOutputStream os = resp.getOutputStream();            ImageIO.write(image, "png", os);        } catch (IOException e) {            throw new RuntimeException("响应验证码失败：" + e.getMessage());        }    }/*    前后端分离项目*/@RestController@CrossOriginpublic class KaptchaController {    @Autowired    private Producer defaultKaptcha;    @GetMapping("/createImageCode")    public void defaultKaptcha(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws Exception {        byte[] captchaOutputStream = null;        ByteArrayOutputStream imgOutputStream = new ByteArrayOutputStream();        try {            //生产验证码字符串并保存到session中            String verifyCode = defaultKaptcha.createText();            httpServletRequest.getSession().setAttribute("verifyCode", verifyCode);            BufferedImage challenge = defaultKaptcha.createImage(verifyCode);            ImageIO.write(challenge, "jpg", imgOutputStream);        } catch (IllegalArgumentException e) {            httpServletResponse.sendError(HttpServletResponse.SC_NOT_FOUND);            return;        }        captchaOutputStream = imgOutputStream.toByteArray();        httpServletResponse.setHeader("Cache-Control", "no-store");        httpServletResponse.setHeader("Pragma", "no-cache");        httpServletResponse.setDateHeader("Expires", 0);        httpServletResponse.setContentType("image/jpeg");        ServletOutputStream responseOutputStream = httpServletResponse.getOutputStream();        responseOutputStream.write(captchaOutputStream);        responseOutputStream.flush();        responseOutputStream.close();    }}

 4、前台页面实现（单体）

5、实现点击验证码切换功能

前后端分离

6、Kaptcha配置表