facebook访问Token 400错误请求

Question

我正在使用以下代码来检索facebook accessToken

string url = "https://graph.facebook.com/oauth/access_token?" +
                         "client_id={0}" +
                         "&redirect_uri={1}" +
                         "&client_secret={2}" +
                         "&code={3}";
            url = string.Format(url, clientId, redirectUri.EncodeUrl(), clientSecret, code);
            //Create a webrequest to perform the request against the Uri
            WebRequest request = WebRequest.Create(url);
            try
            {
                //read out the response as a utf-8 encoding and parse out the access_token
                using (WebResponse response = request.GetResponse())
                {
                    using (Stream stream = response.GetResponseStream())
                    {
                        //string urlRedirects = response.ResponseUri.ToString();
                        Encoding encode = Encoding.GetEncoding("utf-8");
                        if (stream != null)
                        {
                            StreamReader streamReader = new StreamReader(stream, encode);
                            string accessToken = streamReader.ReadToEnd().Replace("access_token=", "");
                            streamReader.Close();
                            response.Close();
                            return accessToken;
                        }
                    }
                }
            }
            catch
            {
                return null;
            }

但是我不断收到这个含糊不清的错误信息

{
"error": {
"message": "Error validating verification code.",
"type": "OAuthException",
"code": 100
}
}

我检查了代码100"无效参数"对我来说并不意味着什么.

有没有人有过类似的问题？

Answer 1

您需要将用户发送到 Facebook 登录页面才能获取有效的code. 然后应该使用该代码来access_token为用户获取。

请遵循身份验证指南。