[HttpPost]
        public ActionResult Login(LogOnModel model, string returnUrl)
        {
            if (ModelState.IsValid)
            {
                RegisteredUser usr = RegisteredUserBLL.AuthenticateUser(model.UserName, model.Password);
                if (usr != null)
                {
                    FormsAuthentication.SetAuthCookie(model.UserName + "|" + usr.RealName + "|" + usr.UserType, model.RememberMe);  //身份验证票，并添加到响应的cookie集合 或者url中 
                    if (Url.IsLocalUrl(returnUrl) && returnUrl.Length > 1 && returnUrl.StartsWith("/")
                        && !returnUrl.StartsWith("//") && !returnUrl.StartsWith("/\\"))
                        return Redirect(returnUrl);                 //转到页面
                    return RedirectToAction("Index", "Home");       //转到页面
                }
                ModelState.AddModelError("", "登录账号或密码不正确");  //数据库没有查询到
            }
            return View(model);
        }

    public class LogOnModel
    {
        [Required]
        [Display(Name = "账号")]
        public string UserName { get; set; }

        [Required]
        [DataType(DataType.Password)]
        [Display(Name = "密码")]
        public string Password { get; set; }

        [Display(Name = "记住登录信息")]
        public bool RememberMe { get; set; }
    }

public static class RegisteredUserBLL
        public static RegisteredUser AuthenticateUser(string loginName, string passwd)
        {
            using(var db=new VODDataContext())
            {
                db.ObjectTrackingEnabled = false;  
                string encPwd = CommonUtils.EncryptPassword(passwd);  //返回一个加密的字符串
                RegisteredUser usr = db.RegisteredUsers.FirstOrDefault(a => a.LoginName == loginName && a.Passwd == encPwd);  ////有相应RegisteredUsers数据库表
                if (usr != null)
                    return usr;
                return null;
            }
        }

    public partial class RegisteredUser:IDataErrorInfo
    {
        public string this[string propName]
        {
            get
            {
                if (propName == "UserName" && string.IsNullOrEmpty(LoginName))
                    return "用户登录名不能为空";
                return string.Empty;
            }
        }

        public string Error
        {
            get { return string.Empty; }
        }
    }