Http客户端的几种请求方式

A: HttpClient  using System.Net.Http;

B:RestSharp   using Flurl.Http;

C:HttpWebRequest (Not recommended for new work)    

using System.Net;
using System.Text;  // for class Encoding
using System.IO;    // for StreamReader

https://stackoverflow.com/questions/4015324/how-to-make-http-post-web-request/4015346?r=SearchResults#4015346