导入包：

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

配置类：

package com.now.community.community.config;import com.google.code.kaptcha.Producer;
import com.google.code.kaptcha.impl.DefaultKaptcha;
import com.google.code.kaptcha.util.Config;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;import java.util.Properties;@Configuration
public class KaptchaConfig {@Beanpublic Producer kaptchaProducer() {Properties properties = new Properties();properties.setProperty("kaptcha.image.width", "100");properties.setProperty("kaptcha.image.height", "40");properties.setProperty("kaptcha.textproducer.font.size", "32");properties.setProperty("kaptcha.textproducer.font.color", "0,0,0");properties.setProperty("kaptcha.textproducer.char.string", "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ");properties.setProperty("kaptcha.textproducer.char.length", "4");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;}}

Controller

    //验证码@RequestMapping(path = "/kaptcha", method = RequestMethod.GET)public void getKaptcha(HttpServletResponse response/*, HttpSession session*/) {// 生成验证码String text = kaptchaProducer.createText();BufferedImage image = kaptchaProducer.createImage(text);//将验证码存入sessionsession.setAttribute("kaptcha", text);// 将图片输出给浏览器response.setContentType("image/png");try {OutputStream os = response.getOutputStream();ImageIO.write(image, "png", os);} catch (IOException e) {logger.error("响应验证码失败:" + e.getMessage());}}

html

<img th:src="@{/kaptcha}" id="kaptcha" style="width:100px;height:40px;" class="mr-2"/>
<a href="javascript:refresh_kaptcha();" class="font-size-12 align-bottom">刷新验证码</a>

js：

jq

善意欺骗，随机数，更新。

<script>function refresh_kaptcha() {var path = CONTEXT_PATH + "/kaptcha?p=" + Math.random();$("#kaptcha").attr("src", path);}
</script>