public void SignIn(FenLei2012.Models.User m)
        {
            if (m != null)
            {
                FormsAuthenticationTicket ticket = new FormsAuthenticationTicket(
                    1,
                    m.UserName,
                    DateTime.Now,
                    DateTime.Now.Add(FormsAuthentication.Timeout),
                    m.RememberMe,
                    m.Roles.Aggregate((i, j) => i + "," + j)
                    );
                System.Web.HttpCookie cookie = new System.Web.HttpCookie(FormsAuthentication.FormsCookieName,FormsAuthentication.Encrypt(ticket));
                System.Web.HttpContext.Current.Response.Cookies.Add(cookie);
            }
}