/// <summary>
        /// 是否强制(挤掉当登录用户)
        /// </summary>
        /// <param name="force"></param>
        public void SignOut(string username, bool force)
        {
            IPrincipal user = new OpenIDPrincipal(new OpenIDIdentity(null), force);

            HttpContext.Current.User = user;
            HttpContext.Current.Session["customidentity"] = user;
        }
        public void SignIn(UserModel userModel)
        {
            IPrincipal user = new OpenIDPrincipal(new OpenIDIdentity(userModel));

            HttpContext.Current.User = user;
            HttpContext.Current.Session["customidentity"] = user;
        }