public IActionResult Showcer()
        {
            this.Request.Cookies.TryGetValue("Sno", out string value);
            CerMethod method = new CerMethod();
            var       cers   = method.GetCertificates(value);

            ViewBag.cers = cers;
            return(View());
        }
        public IActionResult Mycer(Student student)
        {
            var infor = new Student();

            using (var dbcontext = new srContext())
            {
                infor = dbcontext.Student.FirstOrDefault(u => u.Sno == student.Sno);
            }
            CerMethod method = new CerMethod();

            if (infor == null)
            {
                return(Content("<script>alert('该学生不存在');history.go(-1);</script>", "text/html;charset=UTF-8"));
            }
            else
            {
                var cers = method.GetCertificates(student.Sno);
                ViewBag.cers = cers;
                return(View());
            }
        }