private static bool CheckValidationResult(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)

{

return true;

}

private static readonly string DefaultUserAgent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.61 Safari/537.36";

private static bool CheckValidationResult(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)

{

return true;

}

public static string HttpsPost(string url, string postData)

{

Stream outstream = null;

Stream instream = null;

StreamReader sr = null;

HttpWebResponse response = null;

HttpWebRequest request = null;

Encoding encoding = Encoding.GetEncoding("utf-8");  //选择编码字符集

byte[] data = encoding.GetBytes(postData); //转换为bytes数据

// 准备请求...

try

{

// 设置参数

if (url.StartsWith("https", StringComparison.OrdinalIgnoreCase))

{

ServicePointManager.ServerCertificateValidationCallback =

new RemoteCertificateValidationCallback(CheckValidationResult);

System.Net.ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12 | SecurityProtocolType.Ssl3 | (SecurityProtocolType)3072; //必须加上这一句，根据需要更改值

request = WebRequest.create(url) as HttpWebRequest;

request.ProtocolVersion = HttpVersion.Version10;

}

else

{

request = WebRequest.create(url) as HttpWebRequest;

}

CookieContainer cookieContainer = new CookieContainer();

request.CookieContainer = cookieContainer;

request.AllowAutoRedirect = true;

request.Timeout = 30*1000;  //30S

request.ContinueTimeout = 30 * 1000;

request.Method = "POST";

request.ContentType = "application/json";

request.ContentLength = data.Length;

request.UserAgent = DefaultUserAgent;

// request.TransferEncoding = encoding.HeaderName;

outstream = request.GetRequestStream();

outstream.Write(data, 0, data.Length);

outstream.Close();

//发送请求并获取相应回应数据

response = request.GetResponse() as HttpWebResponse;

//直到request.GetResponse()程序才开始向目标网页发送Post请求

instream = response.GetResponseStream();

sr = new StreamReader(instream, encoding);

//返回结果网页（html）代码

string content = sr.ReadToEnd();

string err = string.Empty;

return content;

}

catch (Exception ex)

{

string err = ex.Message;

return string.Empty;

}

}