有几种方法可以执行 HTTPGET和POST请求：

方法A：HttpClient（首选）

适用于：.NET Framework 4.5+, .NET Standard 1.1+, .NET Core 1.0+.

它是目前首选的方法，并且是异步的和高性能的。大多数情况下使用内置版本，但对于非常旧的平台，有一个NuGet
包。

using System.Net.Http;

设置

建议为您的应用程序的生命周期实例化一个HttpClient并共享它，除非您有特定的理由不这样做。

private static readonly HttpClient client = new HttpClient();

查看依赖注入HttpClientFactory解决方案。

• POST

  var values = new Dictionary<string, string>
  

  {
  { “thing1”, “hello” },
  { “thing2”, “world” }
  };

  var content = new FormUrlEncodedContent(values);

  var response = await client.PostAsync("http://www.example.com/recepticle.aspx”, content);

  var responseString = await response.Content.ReadAsStringAsync();

• GET

  var responseString = await client.GetStringAsync("http://www.example.com/recepticle.aspx");
  

方法 B：第三方库

RestSharp

• POST

   var client = new RestClient("http://example.com");
  

  // client.Authenticator = new HttpBasicAuthenticator(username, password);
  var request = new RestRequest(“resource/{id}”);
  request.AddParameter(“thing1”, “Hello”);
  request.AddParameter(“thing2”, “world”);
  request.AddHeader(“header”, “value”);
  request.AddFile(“file”, path);
  var response = client.Post(request);
  var content = response.Content; // Raw content as string
  var response2 = client.Post(request);
  var name = response2.Data.Name;

Flurl.Http

它是一个较新的库，具有流畅的 API、测试助手、在后台使用 HttpClient
并且是可移植的。它可以通过NuGet获得。

    using Flurl.Http;

• POST

  var responseString = await "http://www.example.com/recepticle.aspx"
  .PostUrlEncodedAsync(new { thing1 = "hello", thing2 = "world" })
  .ReceiveString();
  

• GET

  var responseString = await "http://www.example.com/recepticle.aspx"
  .GetStringAsync();
  

方法C：HttpWebRequest（新作品不推荐）

适用于：.NET Framework 1.1+, .NET Standard 2.0+, .NET Core 1.0+. 在 .NET Core
中，它主要是为了兼容性——它是 wrapsHttpClient的，性能较低，并且不会获得新功能。

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

• POST

  var request = (HttpWebRequest)WebRequest.Create("http://www.example.com/recepticle.aspx");
  

  var postData = “thing1=” + Uri.EscapeDataString(“hello”);
  postData += “&thing2=” + Uri.EscapeDataString(“world”);
  var data = Encoding.ASCII.GetBytes(postData);

  request.Method = “POST”;
  request.ContentType = “application/x-www-form-urlencoded”;
  request.ContentLength = data.Length;

  using (var stream = request.GetRequestStream())
  {
  stream.Write(data, 0, data.Length);
  }

  var response = (HttpWebResponse)request.GetResponse();

  var responseString = new StreamReader(response.GetResponseStream()).ReadToEnd();

• GET

  var request = (HttpWebRequest)WebRequest.Create("http://www.example.com/recepticle.aspx");
  

  var response = (HttpWebResponse)request.GetResponse();

  var responseString = new StreamReader(response.GetResponseStream()).ReadToEnd();

方法D：WebClient（新作品不推荐）

这是一个包装器HttpWebRequest。与比较HttpClient。

适用于：.NET Framework 1.1+, NET Standard 2.0+,.NET Core 2.0+

using System.Net;
using System.Collections.Specialized;

• POST

  using (var client = new WebClient())
  

  {
  var values = new NameValueCollection();
  values[“thing1”] = “hello”;
  values[“thing2”] = “world”;

  var response = client.UploadValues("http://www.example.com/recepticle.aspx", values);
  
  var responseString = Encoding.Default.GetString(response);
  

  }

• GET

  using (var client = new WebClient())
  

  {
  var responseString = client.DownloadString("http://www.example.com/recepticle.aspx”);
  }