c#解决WebClient不能下载https网页内容

需要在下载代码之前加入如下代码 

  // 解决WebClient不能通过https下载内容问题
                System.Net.ServicePointManager.ServerCertificateValidationCallback +=
                    delegate(object sender, System.Security.Cryptography.X509Certificates.X509Certificate certificate,
                             System.Security.Cryptography.X509Certificates.X509Chain chain,
                             System.Net.Security.SslPolicyErrors sslPolicyErrors)
                    {
                        return true; // **** Always accept
                    };

上述代码主要是为了跳过https的ssl验证。

完整示例如下：

 private string geihtmlutf8(string url)
        {
            try
            {
                if (url.Substring(0, 5) == "https")
                {
                    // 解决WebClient不能通过https下载内容问题
                    System.Net.ServicePointManager.ServerCertificateValidationCallback +=
                        delegate(object sender, System.Security.Cryptography.X509Certificates.X509Certificate certificate,
                                 System.Security.Cryptography.X509Certificates.X509Chain chain,
                                 System.Net.Security.SslPolicyErrors sslPolicyErrors)
                        {
                            return true; // **** Always accept
                        };
                }
                var hl = new WebClient();
                var hltext = hl.DownloadData(url); //取网页源码
                return (Encoding.GetEncoding("UTF-8").GetString(hltext)); //编码转换
            }
            catch (Exception ex)
            {
                return ex.ToString();
            }
        } //取网页源码

参考文章：https://stackoverflow.com/questions/12506575/how-to-ignore-the-certificate-check-when-ssl/18624335#18624335