public IActionResult VerifyCallBackUrl(PostModel postModel, string echostr)
 {
     if (_authSrv.VerifyCallBackUrl(postModel, echostr))
     {
         return(Content(echostr)); //返回随机字符串则表示验证通过
     }
     else
     {
         return(Content("failed:" + postModel.Signature + "," +
                        Senparc.Weixin.MP.CheckSignature.GetSignature(postModel.Timestamp, postModel.Nonce,
                                                                      WechatAppSettings.Token) + "。" +
                        "如果你在浏览器中看到这句话,说明此地址可以被作为微信公众账号后台的Url,请注意保持Token一致。"));
     }
 }