依赖

 <!-- https://mvnrepository.com/artifact/com.github.axet/kaptcha -->
        <dependency>
            <groupId>com.github.axet</groupId>
            <artifactId>kaptcha</artifactId>
            <version>0.0.9</version>
        </dependency>

servlet-context.xml图形验证码bean配置

 <!--
       图片验证码bean 对象配置
    -->
    <bean id="captchaProducer" class="com.google.code.kaptcha.impl.DefaultKaptcha">
        <property name="config">
            <bean class="com.google.code.kaptcha.util.Config">
                <constructor-arg>
                    <props>
                        <prop key="kaptcha.border">yes</prop><!--是否有边框 -->
                        <prop key="kaptcha.border.color">105,179,90</prop><!--设置边框颜色 -->
                        <prop key="kaptcha.textproducer.font.color">green</prop><!--验证码文本字符颜色 默认为Color.BLACK -->
                        <prop key="kaptcha.session.key">code</prop><!--验证码 -->
                        <prop key="kaptcha.textproducer.font.names">宋体,楷体,微软雅黑</prop><!--设置字体样式 -->
                        <prop key="kaptcha.border.thickness"></prop><!--边框粗细度 默认为1 -->
                        <prop key="kaptcha.producer.impl"></prop><!--验证码生成器 默认为DefaultKaptcha -->
                        <prop key="kaptcha.textproducer.impl"></prop><!-- 验证码文本生成器 默认为DefaultTextCreator -->
                        <prop key="kaptcha.textproducer.char.string"></prop><!--验证码文本字符内容范围 默认为abcde2345678gfynmnpwx -->
                        <prop key="kaptcha.textproducer.char.length">4</prop><!-- 验证码文本字符长度 默认为5 -->
                        <prop key="kaptcha.textproducer.font.size">40</prop><!--验证码文本字符大小 默认为40 -->
                        <prop key="kaptcha.textproducer.char.space">6</prop>    <!--验证码文本字符间距 默认为2 -->
                        <prop key="kaptcha.image.width">200</prop>    <!--验证码图片宽度 默认为200 -->
                        <prop key="kaptcha.image.height">50</prop> <!--验证码图片高度 默认为40 -->
                    </props>
                </constructor-arg>
            </bean>
        </property>
    </bean>

controller接口

package com.credi.xmjf.web.controller;

import com.google.code.kaptcha.Producer;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

import javax.annotation.Resource;
import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;

/**
 * Created by Administrator on 2019/6/23.
 */
@Controller
public class ImageController {

    //图形验证码接口注入
    @Resource
    private Producer producer;

    @RequestMapping("image")
    public void getImage(HttpServletResponse response, HttpServletRequest request){
        // 响应头信息设置
        response.setDateHeader("Expires", 0);
        // Set standard HTTP/1.1 no-cache headers.
        response.setHeader("Cache-Control", "no-store, no-cache, must-revalidate");
        // Set IE extended HTTP/1.1 no-cache headers (use addHeader).
        response.addHeader("Cache-Control", "post-check=0, pre-check=0");
        // Set standard HTTP/1.0 no-cache header.
        response.setHeader("Pragma", "no-cache");
        // return a jpeg
        response.setContentType("image/jpeg");

        // 验证码文本数字
        String code=producer.createText();

        // 将验证码存入session
        request.getSession().setAttribute("image",code);

        // 验证码图片对象
        BufferedImage bi=producer.createImage(code);

        // 输出流
        OutputStream os=null;
        try {
            os=response.getOutputStream();
            ImageIO.write(bi,"jpg",os); // bi:图片对象 , "jpg":图片格式 , os:输出流
            os.flush();
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            if(null !=os){
                try {
                    os.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

}

前端

• ftl

<!--访问接口 , 得到验证码图片-->
[外链图片转存失败(img-VX64MbtS-1562055061097)(https://mp.csdn.net/mdeditor/$%7Bctx%7D/image)]

• js

// 点击验证码,生成新的验证码
$(function () {
   $(".validImg").click(function () {
      $(this).attr("src",ctx+"/image?time="+new Date());
   })
});