登录样式是不是很好看

1.导入依赖

    <!-- 验证码 -->
        <dependency>
            <groupId>com.github.penggle</groupId>
            <artifactId>kaptcha</artifactId>
            <version>2.3.2</version>
        </dependency>

2.创建工具类

CommonController
package com.mine.controller.common;

import com.google.code.kaptcha.impl.DefaultKaptcha;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;

import javax.imageio.ImageIO;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;

/*
验证码
 */

@Controller
public class CommonController {

    @Autowired
    private DefaultKaptcha captchaProducer;

    @GetMapping("/common/kaptcha")
    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 = captchaProducer.createText();
            httpServletRequest.getSession().setAttribute("verifyCode", verifyCode);
            BufferedImage challenge = captchaProducer.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();
    }
}
KaptchaConfig
package com.mine.controller.common;

import com.google.code.kaptcha.impl.DefaultKaptcha;
import com.google.code.kaptcha.util.Config;
import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Component;

import java.util.Properties;

@Component
public class KaptchaConfig {
    @Bean
    public DefaultKaptcha getDefaultKaptcha(){
        DefaultKaptcha defaultKaptcha = new DefaultKaptcha();
        Properties properties = new Properties();
        properties.put("kaptcha.border", "no");
        properties.put("kaptcha.textproducer.font.color", "black");
        properties.put("kaptcha.image.width", "150");
        properties.put("kaptcha.image.height", "40");
        properties.put("kaptcha.textproducer.font.size", "30");
        properties.put("kaptcha.session.key", "verifyCode");
        properties.put("kaptcha.textproducer.char.space", "5");
        Config config = new Config(properties);
        defaultKaptcha.setConfig(config);

        return defaultKaptcha;
    }
}

3. 前端页面

    <div class="txt">
        <input type="text" name="verifyCode" placeholder="请输入验证码">
        <div class="ver">
            <img alt="单击图片刷新！" class="pointer" th:src="@{/common/kaptcha}"
                 onclick="this.src='/common/kaptcha?d='+new Date()*1">
        </div>
    </div>