Springboot使用kaptcha验证码

@Configuration
public class KaptchaConfig {
    @Bean
    public DefaultKaptcha kaptcha() {
        DefaultKaptcha kaptcha = new DefaultKaptcha();
        // 设置验证码生成器的属性
        // 可以根据需要进行配置，例如边框、字符长度、字体颜色、图片大小等
        Properties properties = new Properties();
        properties.setProperty("kaptcha.border", "no");
        properties.setProperty("kaptcha.textproducer.char.length", "4");
        properties.setProperty("kaptcha.textproducer.font.color", "black");
        properties.setProperty("kaptcha.textproducer.font.size", "30");
        properties.setProperty("kaptcha.image.width", "200");
        properties.setProperty("kaptcha.image.height", "55");
        Config config = new Config(properties);
        kaptcha.setConfig(config);
        return kaptcha;
    }
}

@RestController
@CrossOrigin
@RequestMapping("/api")
public class CaptchaController {
    private final DefaultKaptcha kaptcha;

    public CaptchaController(DefaultKaptcha kaptcha) {
        this.kaptcha = kaptcha;
    }

    @Operation(summary = "发送图片验证码")
    @GetMapping("/captcha")
    public void generateCaptcha(HttpServletResponse response, HttpServletRequest request) throws IOException {
        // 生成验证码
        String captchaText = kaptcha.createText();
        // 将验证码存储到会话中，以便后续验证
        HttpSession session = request.getSession();
        session.setAttribute("captcha", captchaText);
        request.getServletContext();
        // 将验证码图片输出到响应中
        response.setContentType("image/jpeg");
        try (OutputStream outputStream = response.getOutputStream()) {
            BufferedImage captchaImage = kaptcha.createImage(captchaText);
            ImageIO.write(captchaImage, "jpg", outputStream);
            outputStream.flush();
        }
    }

<el-image src="/app/api/captcha" fit="contain"></el-image>