var dTimeOut = FormsAuthentication.Timeout.TotalMinutes;
            var ticket = new FormsAuthenticationTicket(1, user.UserId, DateTime.Now,
                DateTime.Now.AddMinutes(dTimeOut), true, userType, FormsAuthentication.FormsCookiePath);
            var identity = new FormsIdentity(ticket);


            var gp = new GenericPrincipal(identity, new string[] { userType });
            HttpContext.User = gp;
            var cookieValue = FormsAuthentication.Encrypt(ticket);
            var cookie = new HttpCookie(FormsAuthentication.FormsCookieName, cookieValue)
            {
                Secure = FormsAuthentication.RequireSSL,
                Domain = FormsAuthentication.CookieDomain,
                Path = FormsAuthentication.FormsCookiePath
            };
            HttpContext.Response.Cookies.Add(cookie);

        void MvcApplication_AuthorizeRequest(object sender, EventArgs e)
        {
            if (System.Web.HttpContext.Current.User == null) return;
            if (!Context.User.Identity.IsAuthenticated) return;

            var id = Context.User.Identity as FormsIdentity;
            if (id == null) return;
            var roles = new string[] { id.Ticket.UserData };
            Context.User = new GenericPrincipal(id, roles);
        }

//假设传过来用户User,//isPersistent是你的True,我用3个方法给你优化下
public static void SignIn(User user, bool isPersistent)
        {
            // 如果登录成功 则做此设置 表明验证通过
            // 输入的 username 用来作为登录验证票据 tick 的一部分
            // persistence cookie 如果为false 则为回话cookie 浏览器关闭就失效，如果为 true 则有效期为配置中的 timeout
            FormsAuthentication.SetAuthCookie(user.UserName, isPersistent); // 此方法设置要安全可靠

            CookieHelper.SetAuthCookieTicket(user);
            CookieHelper.SetUserCookie(user);
        }
//我们实现CookieHelper方法：里面的2个扩展方法：
1：SetAuthCookieTicket
public static void SetAuthCookieTicket(User user)
        {
            var response = HttpContext.Current.Response;
            var cookie = response.Cookies.Get(FormsAuthentication.FormsCookieName);
            if (cookie == null) return;

            var permissions = new List<string>();
            var oldTicket = FormsAuthentication.Decrypt(cookie.Value);
            if (oldTicket == null) return;

            var newTicket = new FormsAuthenticationTicket(oldTicket.Version,
                oldTicket.Name,
                oldTicket.IssueDate,
                oldTicket.Expiration,
                oldTicket.IsPersistent,
                //这里设置新的内容
                permissions.Join(",")
                );
            //cookieValue 
            cookie.Value = FormsAuthentication.Encrypt(newTicket);
        }
2：扩展方法SetUserCookie
 public static void SetUserCookie(User user)
        {
            var cookie = new HttpCookie(UserCookieName)
            {
                Expires = DateTime.UtcNow.Add(FormsAuthentication.Timeout),
                Secure = FormsAuthentication.RequireSSL,
                HttpOnly = true
            };

            cookie.Values.Add("uid", user.Id.ToString(CultureInfo.InvariantCulture));
            cookie.Values.Add("displayname", user.DisplayName);

            HttpContext.Current.Response.Cookies.Add(cookie);