未能创建 SSL/TLS 安全通道解决方案

操作

当向一个https的url上发送请求，报错：未能创建 SSL/TLS 安全通道；

报错前实现代码如下：

/// <summary>
/// 判断远程文件是否存在
/// </summary>
/// <param name="fileUrl">文件路径</param>
/// <returns></returns>
public ActionResult FileExists(string fileUrl)
{
var result = new ResultModel();
HttpWebRequest re = null;
HttpWebResponse res = null;
try
{

re = (HttpWebRequest)WebRequest.Create(fileUrl);
res = (HttpWebResponse)re.GetResponse();
if (res.ContentLength != 0)
{
result.Success = true;
}
}
catch (Exception ex)
{

result.Success = false;
result.Message =  ex.Message;

}
finally
{
if (re != null)
{
re.Abort();//销毁关闭连接
}
if (res != null)
{
res.Close();//销毁关闭响应
}
}
return Json(result, JsonRequestBehavior.AllowGet);
}

原因：

ssl证书不受信任，验证失败；

解决方案：

1：先加入命名空间

using System.Net.Security;    
using System.Security.Authentication;
using System.Security.Cryptography.X509Certificates;

2：再重载CheckValidationResult方法，返回true

public static bool CheckValidationResult(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors errors)         {

            //直接确认，否则打不开    

            return true;

        }

3：然后在HttpWebRequest req =（HttpWebRequest） WebRequest.Create(URL)前面加上如下一行代码

ServicePointManager.ServerCertificateValidationCallback = new System.Net.Security.RemoteCertificateValidationCallback(CheckValidationResult);//验证服务器证书回调自动验

最终实现代码如下：

  /// <summary>
        /// 判断远程文件是否存在
        /// </summary>
        /// <param name="fileUrl">文件路径</param>
        /// <returns></returns>
        public ActionResult FileExists(string fileUrl)
        {
            var result = new ResultModel();
            HttpWebRequest re = null;
            HttpWebResponse res = null;
            try
            {
                ServicePointManager.ServerCertificateValidationCallback = new System.Net.Security.RemoteCertificateValidationCallback(CheckValidationResult);
                re = (HttpWebRequest)WebRequest.Create(fileUrl);
                res = (HttpWebResponse)re.GetResponse();
                if (res.ContentLength != 0)
                {
                    result.Success = true;
                }
            }
            catch (Exception ex)
            {

                result.Success = false;
                result.Message =ex.Message;

            }
            finally
            {
                if (re != null)
                {
                    re.Abort();//销毁关闭连接
                }
                if (res != null)
                {
                    res.Close();//销毁关闭响应
                }
            }
            return Json(result, JsonRequestBehavior.AllowGet);
        }