一、依赖

<dependency>

    <groupId>com.github.penggle</groupId>

    <artifactId>kaptcha</artifactId>

    <version>2.3.2</version>

</dependency>

二、springmvc配置文件

<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>

                        <prop key="kaptcha.border.color">105,179,90</prop>

                        <prop key="kaptcha.textproducer.font.color">blue</prop>

                        <prop key="kaptcha.image.width">125</prop>

                        <prop key="kaptcha.image.height">45</prop>

                        <prop key="kaptcha.textproducer.font.size">45</prop>

                        <prop key="kaptcha.session.key">code</prop>

                        <prop key="kaptcha.textproducer.char.length">4</prop>

                        <prop key="kaptcha.textproducer.font.names">宋体,楷体,微软雅黑</prop>

                    </props>

                </constructor-arg>

            </bean>

        </property>

    </bean>

三、编码

1.后端

controler类：

    package com.neusoft.controller;

import java.awt.image.BufferedImage;

import javax.imageio.ImageIO;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;

import com.google.code.kaptcha.Constants;
import com.google.code.kaptcha.Producer;
    
@Controller
@RequestMapping(value="/code")
public class codeController {

     @Autowired
     private Producer captchaProducer = null;

        @RequestMapping(value = "/getcode")
        public ModelAndView getKaptchaImage(HttpServletRequest request, HttpServletResponse response) throws Exception {
            HttpSession session = request.getSession();
            response.setDateHeader("Expires", 0);
            response.setHeader("Cache-Control", "no-store, no-cache, must-revalidate");
            response.addHeader("Cache-Control", "post-check=0, pre-check=0");
            response.setHeader("Pragma", "no-cache");
            response.setContentType("image/jpeg");
            //生成验证码
            String capText = captchaProducer.createText();
            session.setAttribute(Constants.KAPTCHA_SESSION_KEY, capText);
            //向客户端写出
            BufferedImage bi = captchaProducer.createImage(capText);
            ServletOutputStream out = response.getOutputStream();
            ImageIO.write(bi, "jpg", out);
            try {
                out.flush();
            } finally {
                out.close();
            }
           return null; 
        }
}

2.前端

<div class="form-group">

    <div class="row">

        <div class="col-sm-8">

            <input type="text" id="code" class="form-control" placeholder="验证码" data-toggle="tooltip" data-placement="top">

        </div>

        <div class="col-sm-4">

            <img id="codeImg" src="http://127.0.0.1:8666/sys/captcha" class="img-responsive" style="display: block;width:100%;height: 32px">

        </div>

    </div>

</div>

3.效果图