校园选课助手【6】-使用验证码验证抢课接口

需求分析：抢课开放时，大量用户同时访问抢课接口，防止有人利用程序恶意刷接口进行抢课。

1.导入验证码依赖

    <!--验证码依赖-->
    <dependency>
      <groupId>com.github.whvcse</groupId>
      <artifactId>easy-captcha</artifactId>
      <version>1.6.2</version>
    </dependency>

2.前端判断抢课时间是否开始，一旦开始用户点击某个课程进入抢课页面就向服务器发送请求，服务器j进行响应生成验证码结果：

<div class="row">
     <div class="form-inline">
          <img id="captchaImg" width="130" height="32" onclick="refreshCaptcha()"/>
            <input id="captcha" class="form-control">
           <button class="btn btn-primary btn-block" type="button" id ="buyButton" onclick="getSeckillPath()">立即秒杀
            <input type="hidden" name="courseId" id ="courseId">
       </button>
   </div>
 </div>
    function refreshCaptcha() {
        $("#captchaImg").attr("src", "/seckill/captcha?courseId=" + $("#courseId")
            .val() + "&time=" + new Date());
    }

/    @ApiOperation("获取验证码")
    @GetMapping(value = "/captcha")
    public void verifyCode(User tUser, Long goodsId, HttpServletResponse response) {
        if (tUser == null || goodsId < 0) {
            throw new GlobalException(RespBeanEnum.REQUEST_ILLEGAL);
        }
        //设置请求头为输出图片的类型
        response.setContentType("image/jpg");
        response.setHeader("Pargam", "No-cache");
        response.setHeader("Cache-Control", "no-cache");
        response.setDateHeader("Expires", 0);
        //生成验证码
        ArithmeticCaptcha captcha = new ArithmeticCaptcha(130, 32, 3);
        redisTemplate.opsForValue().set("captcha:" + tUser.getId() + ":" + goodsId, captcha.text(), 300, TimeUnit.SECONDS);
        try {
            captcha.out(response.getOutputStream());
        } catch (IOException e) {
            log.error("验证码生成失败", e.getMessage());
        }
    }

3.CourseOrderservice中编写验证码检验逻辑代码，使用的是数字验证码，用户输入结果后传入与Redis中预存的结果进行比较

//接口
    boolean checkCaptcha(User tuser, Long goodsId, String captcha);

    @Override
    public boolean checkCaptcha(User user, Long goodsId, String captcha) {
        if (user == null || goodsId < 0 || StringUtils.isEmpty(captcha)) {
            return false;
        }
        String redisCaptcha = (String) redisTemplate.opsForValue().get("captcha:" + user.getId() + ":" + goodsId);
        return captcha.equals(redisCaptcha);
    }