1、认证

public async Task<WxResult> AuthenticationAsync(string code)
        {
            var appId = ConfigurationManager.AppSettings["WeChat:Appid"];
            var appSecret = ConfigurationManager.AppSettings["WeChat:Secret"];
            var url = $"https://api.weixin.qq.com/sns/jscode2session?appid={appId}&secret={appSecret}&js_code={code}&grant_type=authorization_code"; 
            var webRequest = WebRequest.CreateHttp(url);
            webRequest.Method = "Get";
            var webResponse = (HttpWebResponse)webRequest.GetResponse();
            if (webResponse.StatusCode == HttpStatusCode.OK)
            {
                using (var stream = webResponse.GetResponseStream())
                {
                    using (var reader = new StreamReader(stream))
                    {
                        string content = await reader.ReadToEndAsync();
                        var result=JsonConvert.DeserializeObject<WxAuthenticationResultModel>(content);
                        if(string.IsNullOrEmpty(result?.openid))
                            return new WxAuthenticationFailedResult("微信接口openid为空");
                        return new WxAuthenticationSucceedResult() { OpenId = result.openid };
                    }
                }
            }
            else {
                return new WxAuthenticationFailedResult("微信接口调用失败");
            }
        }