/// <summary>
/// 验证微信访问
/// </summary>
public static void Auth(HttpContext webContext)
{

    string requestURL = webContext.Request.Url.AbsoluteUri;

    try
    {
        // 用户访问微信页面有3种情况：
        // 1.第一次访问，没code
        // 2.有code，没cookie；
        // 3.有code，有cookie

        // 1.第一次访问，没code，没cookie：跳转到Oauth2.0认证
        if (string.IsNullOrEmpty(webContext.Request["code"]))
        {
            string url = string.Format("https://open.weixin.qq.com/connect/oauth2/authorize?appid={0}&redirect_uri={1}&response_type=code&scope=snsapi_base&state=STATE#wechat_redirect", CORPID, webContext.Server.UrlEncode(requestURL));
            webContext.Response.Redirect(url, false);
        }
        else if (!string.IsNullOrEmpty(webContext.Request["code"]) && string.IsNullOrEmpty(CookieHelper.GetCookie("WXToken")))
        {
            // 2.有code，没cookie：根据code获取userID
            string code = webContext.Request["code"];
            string userId = "";
            string userInfo = "";

            #region 1)根据code获取userId

            string url = string.Format("https://qyapi.weixin.qq.com/cgi-bin/user/getuserinfo?access_token={0}&code={1}", GetAccessToken(), code);
            string responseText = HttpHelper.Instance.get(url);
            /*
                API：http://qydev.weixin.qq.com/wiki/index.php?title=OAuth%E9%AA%8C%E8%AF%81%E6%8E%A5%E5%8F%A3#.E6.A0.B9.E6.8D.AEcode.E8.8E.B7.E5.8F.96.E6.88.90.E5.91.98.E4.BF.A1.E6.81.AF
                正确的Json返回示例:
                {
                   "UserId":"USERID",
                   "DeviceId":"DEVICEID"
                }
                未关注企业号时返回：
                {
                   "OpenId":"OPENID",
                   "DeviceId":"DEVICEID"
                }
                错误的Json返回示例:
                {
                   "errcode": "40029",
                   "errmsg": "invalid code"
                }
            */
            WeChatUserCodeEntity codeEn = JsonHelper.GetEntity<WeChatUserCodeEntity>(responseText);
            if (codeEn.errcode > 0)
            {
                throw new Exception(codeEn.errmsg);
            }
            else if (string.IsNullOrEmpty(codeEn.UserId))
            {
                throw new Exception("请先关注企业号!");
            }
            userId = codeEn.UserId;


            #endregion

            #region 2)根据userId获取用户信息

            url = string.Format("https://qyapi.weixin.qq.com/cgi-bin/user/get?access_token={0}&userid={1}", GetAccessToken(), userId);
            responseText = HttpHelper.Instance.get(url);
            /*
                API：http://qydev.weixin.qq.com/wiki/index.php?title=%E7%AE%A1%E7%90%86%E6%88%90%E5%91%98#.E8.8E.B7.E5.8F.96.E6.88.90.E5.91.98
                正确的Json返回示例:
                {
                   "errcode": 0,
                   "errmsg": "ok",
                   "userid": "zhangsan",
                   "name": "李四",
                   "department": [1, 2],
                   "position": "后台工程师",
                   "mobile": "15913215421",
                   "gender": "1",
                   "email": "zhangsan@gzdev.com",
                   "weixinid": "lisifordev",  
                   "avatar": "http://wx.qlogo.cn/mmopen/ajNVdqHZLLA3WJ6DSZUfiakYe37PKnQhBIeOQBO4czqrnZDS79FH5Wm5m4X69TBicnHFlhiafvDwklOpZeXYQQ2icg/0",
                   "status": 1,
                   "extattr": {"attrs":[{"name":"爱好","value":"旅游"},{"name":"卡号","value":"1234567234"}]}
                }
                错误的Json返回示例:
                {
                   "errcode": "40029",
                   "errmsg": "invalid code"
                }
            */
            WeChatUserInfoEntity userInfoEn = JsonHelper.GetEntity<WeChatUserInfoEntity>(responseText);
            if (userInfoEn.errcode > 0)
            {
                throw new Exception(userInfoEn.errmsg);
            }
            userInfo = responseText;

            #endregion

            // 3.把userInfo传入到cookie里
            CookieHelper.SetCookie("WXToken", userInfo, -1);
        }
        else if (!string.IsNullOrEmpty(webContext.Request["code"]) && !string.IsNullOrEmpty(CookieHelper.GetCookie("WXToken")))
        {
            #region 3.有code，有cookie：校验cookie
            // TODO：在上面进行存入cookie时可采用AES加密，在这部进行解密校验
            // CookieHelper.SetCookie("WXToken", "", -1);
            #endregion
        }
        else
        {
            throw new Exception("非授权访问！");
        }

    }
    catch (Exception ex)
    {
        throw ex;
    }
}