SpringBoot发送邮件功能 验证码5分钟过期

 private static final String SYMBOLS = "0123456789";
 /**
  * Math.random生成的是一般随机数，采用的是类似于统计学的随机数生成规则，其输出结果很容易预测，因此可能导致被攻击者击中。
  * 而SecureRandom是真随机数，采用的是类似于密码学的随机数生成规则，其输出结果较难预测，若想要预防被攻击者攻击，最好做到使攻击者根本无法，或不可能鉴别生成的随机值和真正的随机值。
  */
 private static final Random RANDOM = new SecureRandom();

 public static String generateVerCode() {
  char[] nonceChars = new char[6];
  for (int i = 0; i < nonceChars.length; i++) {
   nonceChars[i] = SYMBOLS.charAt(RANDOM.nextInt(nonceChars.length));
  }
  return new String(nonceChars);
 }

 /**
  *计算两个日期的分钟差
  */
 public static int getMinute(Date fromDate, Date toDate) {
  return (int) (toDate.getTime() - fromDate.getTime()) / (60 * 1000);

 /**
  * 发送验证码到指定邮箱
  * @param sender 发送地址
  * @param mailSender spring自带
  * @param receiver 接受地址
  */
 AdvanceResponse getCode(String sender,JavaMailSenderImpl mailSender,String receiver);
 /**
  * 注册用户
  */
 AdvanceResponse addUser(User user,String verCode);

/**
 * 验证码
*/
private String code;
/**
 * 发送时间
*/
private Date sendTime;
 @Override
 @Async
 public AdvanceResponse getCode(String sender, JavaMailSenderImpl mailSender, String receiver) {
  SimpleMailMessage message = new SimpleMailMessage();
  message.setSubject("验证码");//设置邮件标题
  code = VerCodeGenerateUtil.generateVerCode();
  sendTime = new Date();
  message.setText("尊敬的用户,您好:\n"
    + "\n本次请求的邮件验证码为:" + code + ",本验证码5分钟内有效，请及时输入。（请勿泄露此验证码）\n"
    + "\n如非本人操作，请忽略该邮件。\n(这是一封自动发送的邮件，请不要直接回复）"); //设置邮件正文
  message.setFrom(sender);//发件人
  message.setTo(receiver);//收件人
  mailSender.send(message);//发送邮件
  return AdvanceResponse.successResponse();
 }

 @Override
 public AdvanceResponse addUser(User user, String verCode) {
  Date date = new Date();
  //判断验证码
  if (VerCodeGenerateUtil.getMinute(sendTime, date) > 5) {
   return AdvanceResponse.failedResponse("验证码已经失效！！！");
  }
  if (!verCode.equals(code)) {
   return AdvanceResponse.failedResponse("验证码不正确！！！");
  }
  user.setRole(0);
  user.setCreateTime(date);
  user.setUpdateTime(date);
  userDao.insert(user);
  code = null;
  return AdvanceResponse.successResponse();
 }

@Autowired
 private UserService userService;
 @Autowired
 private JavaMailSenderImpl mailSender;
 @Value("${spring.mail.username}")
 private String sender;
 
 /**
  * 发送验证码到指定邮箱
  */
 @GetMapping("/verCode")
 public AdvanceResponse verCode(String receiver) {
  return userService.getCode(sender, mailSender, receiver);
 }

 /**
  * 注册用户
  */
 @PostMapping("/addUser")
 public AdvanceResponse addUser(User user, String sender, JavaMailSenderImpl mailSender, @RequestParam("verCode") String verCode) {
  return userService.addUser(user,verCode);
 }

 <div class="layui-form-item">
    <label for="email" class="layui-form-label">
     <span class="x-red">*</span>邮箱
    </label>
    <div class="layui-input-inline">
     <input type="email" id="email" name="email" required="" lay-verify="email"
       autocomplete="off" class="layui-input">
    </div>
    <div class="layui-form-mid layui-word-aux">
     <span class="x-red" id="emailMsg"></span>
    </div>
    <button type="button" class="layui-btn" id="code">获取验证码</button>
   </div>
   <div class="layui-form-item">
    <label for="verCode" class="layui-form-label">
     <span class="x-red">*</span>验证码
    </label>
    <div class="layui-input-inline">
     <input type="text" id="verCode" name="verCode" required=""
       autocomplete="off" class="layui-input">
    </div>
    <div class="layui-form-mid layui-word-aux">
     <span class="x-red" id="verCodeMsg"></span>
    </div>
</div>

 //获取验证码
 $('#code').click(function () {
  const email = $('#email').val();
  const myReg = /^[a-zA-Z0-9_-]+@([a-zA-Z0-9]+\.)+(com|cn|net|org)$/;
  if (email === null || email.length === 0) {
   layer.msg('邮箱不能为空！', {time: 1500, icon: 5, shift: 6});
   return false;
  }
  if (!myReg.test(email)) {
   layer.msg('邮箱格式不正确！', {time: 1500, icon: 5, shift: 6});
   return false;
  }
  $.ajax({
   type: 'GET',
   url: 'user/verCode',
   data: {
    'receiver': email
   },
   beforeSend: function () {
    loading = layer.msg('处理中', {icon: 16})
   },
   success: function () {
    layer.close(loading);
   }
  })
 });
 //这是提交表单，只保留关键部分
 $.ajax({
   type: 'POST',
   url: 'user/addUser',
   data: formData,
   cache: false,   // 不缓存
   processData: false,  // jQuery不要去处理发送的数据
   contentType: false,  // jQuery不要去设置Content-Type请求头
   beforeSend: function () {
    loading = layer.msg('处理中', {icon: 16})
   },
   success: function (result) {
    if (result.status === 0) {
     layer.msg(result.msg, {time: 1500, icon: 5, shift: 6});
    } else {
     layer.close(loading);
     xadmin.close();
    }
   }
  })