关于解决 请求被中止：无法建立SSL / TLS安全通道

我使用HttpWebRequest访问其他网站时,出现"请求被中止：无法建立 SSL / TLS安全通道"错误,于是goog和百度了一番,提供的答案基本 是:ServicePointManager.ServerCertificateValidationCallback写委托

public ResponseModel GetHtml( string url)
{

ServicePointManager.ServerCertificateValidationCallback = ValidateServerCertificate;

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);

}

private bool ValidateServerCertificate( object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
{
return true ;
}

 但这种方法对我无效,该出现的错误还是继续出现.

最终解决办法是,在访问url前执行语句  ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3;即可

public ResponseModel GetHtml( string url)
{
     ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3;
　　　HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
}