Http Basic认证的请求头
public static string HttpPost(string url, string body, string usernamePassword)
{
try
{
//ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(CheckValidationResult);
ServicePointManager.ServerCertificateValidationCallback = Callback;
Encoding encoding = Encoding.UTF8;
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);