public ActionResult LogOn()

        {

            string liveUrl =

                string.Format(

                    "https://login.live.com/oauth20_authorize.srf?client_id={0}&scope=wl.Emails&response_type=code&redirect_uri={1}&locale={2}",

                    this.ClientId,

                    this.OAuthLogOnCallbackUrl,

                    this.Locale);

            return this.Redirect(liveUrl);

        }

        public async Task<ActionResult> LogOnCallback()

        {

            string code = this.Request.QueryString["code"];

            if (string.IsNullOrEmpty(code))

                return RedirectToAction("Index", "Login");

            string tokenUrl =

                string.Format(

                    "https://login.live.com/oauth20_token.srf?client_id={0}&redirect_uri={1}&client_secret={2}&code={3}&grant_type=authorization_code&locale={4}",

                    this.ClientId,

                    this.OAuthLogOnCallbackUrl,

                    this.ClientSecret,

                    code,

                    this.Locale);

            string liveId = string.Empty;

            try

            {

                liveId = await RequestLiveIdByToken(await RequestToken(tokenUrl));

            }

            catch (Exception e)

            {

                _logger.Fatal("无法获取LiveId Token", e);

                var result = new ViewModels.LoginResult

                {

                    Success = false,

                    ErrorMessage = "无法连接登录服务，请稍后再试。"

                };

                return View("Index", result);

            }

            if (!string.IsNullOrEmpty(liveId))

            {

                var userSvc = _userSvc;

                if (userSvc.CurrentUser == null)

                {

                    UserInfo user = userSvc.GetUserByEmail(liveId);

                    if (user != null && user.IsEnable)

                    {

                        return this.DoLogin(user);

                    }

                    else

                    {

                        var result = new ViewModels.LoginResult

                        {

                            Success = false

                        };

                        if (user != null && !user.IsEnable)

                        {

                            result.ErrorMessage = "用户被禁止登录！";

                        }

                        else

                        {

                            result.ErrorMessage = "用户不存在！";

                        }

                        return View("Index", result);

                    }

                }

                return this.DoLogin(userSvc.CurrentUser);

            }

            return this.RedirectToAction("Index", "Login");

        }

        [NonAction]

        private async Task<string> RequestToken(string url)

        {

            var request = WebRequest.Create(url);

            using (var response = await request.GetResponseAsync())

            {

                using (var sr = new StreamReader(response.GetResponseStream()))

                {

                    var json = sr.ReadToEnd();

                    return JsonConvert.DeserializeAnonymousType(json, new { access_token = "" }).access_token;

                }

            }

        }

        [NonAction]

        private async Task<string> RequestLiveIdByToken(string token)

        {

            if (string.IsNullOrEmpty(token))

                return string.Empty;

            var request = WebRequest.Create(string.Format("https://apis.live.net/v5.0/me?access_token={0}", token));

            using (var response = await request.GetResponseAsync())

            {

                using (var sr = new StreamReader(response.GetResponseStream()))

                {

                    string json = sr.ReadToEnd();

                    var userJson = JsonConvert.DeserializeAnonymousType(json, new { emails = new { account = "" } });

                    return userJson.emails.account;

                }

            }

        }

        public ActionResult LogOff()

        {

            this.PreLogout();

            string liveUrl =

                string.Format(

                    "https://login.live.com/oauth20_logout.srf?client_id={0}&scope=wl.Emails&response_type=code&redirect_uri={1}&locale={2}",

                    this.ClientId,

                    this.OAuthLogOnCallbackUrl,

                    this.Locale);

            return this.Redirect(liveUrl);

        }