SpringMV+HuTool之验证码登录

<!-- hutool -->
    <dependency>
      <groupId>cn.hutool</groupId>
      <artifactId>hutool-all</artifactId>
      <version>4.6.8</version>
    </dependency>

<div class="form-group">
                    <label for="validateCode" class="col-sm-3 control-label">验证码:</label>
                    <div class="col-sm-9 ">
                        <div class="row">
                            <div class="col-md-5 form-inline">
                                <img src='${pageContext.request.contextPath}/vericode/showCode' alt='' id='sr' onclick='chance()' height='50px' >
                                <input type="text" class="form-control" id="validateCode" name="code" placeholder="validateCode" style="170px">
                            </div>
                            <div class="col-md-7">
                                <span>请输入图片中的四个字母。<a href="">看不清楚？换个图片</a></span>
                            </div>
                        </div>
                    </div>
                </div>
<!--动态点击验证码的实现-->

<script type="text/javascript">
function chance() {
var img=document.getElementById("sr");
img.src="${pageContext.request.contextPath}/vericode/showCode?a="+ Math.random();
      }
</script>

@Controller
public class CodeController {
    @RequestMapping("/vericode/showCode")
    @ResponseBody
    public void showCode(HttpServletRequest request, HttpServletResponse response,HttpSession session) throws Exception {
        System.out.println("121212");
        //构建验证码图片
        CircleCaptcha captcha = CaptchaUtil.createCircleCaptcha(80, 30, 4, 6);
        //添加验证码
        String codeString = captcha.getCode();
        //将验证码放入session供后续验证
        session.setAttribute("captcha", captcha);
        ServletOutputStream outputStream = response.getOutputStream();
        //将验证码写回页面
        captcha.write(outputStream);
    }

}