HttpClientSample.cs

using System;
using System.Net.Http;
using System.Threading.Tasks;
using System.Net.Http.Headers;

namespace CookieCheck
{
	class MainClass
	{
		public static void Main (string[] args)
		{
			Console.WriteLine ("Hello World!");

			var uri = "http://localhost:8000/a.txt";

			var handler = new HttpClientHandler()
            {
                UseCookies = true,
            };
            var cookieContainer = new System.Net.CookieContainer();
            var cookie = new System.Net.Cookie("guest_id", "v1%3A139109610161149543");
            cookieContainer.Add(new Uri("http://localhost/"), cookie);

            handler.CookieContainer = cookieContainer;

            var client = new HttpClient(handler);
            client.DefaultRequestHeaders.Add("Accept", "*/*");
            Console.WriteLine("Accept: {0}", client.DefaultRequestHeaders.Accept);
            
            // むり
            //client.DefaultRequestHeaders.Add ("Cookie", "guest_id=v1%3A139109610161149543");
            
			var t = Task.Run (async () => {
				using (var response = await client.GetAsync (uri).ConfigureAwait (false)) {
					var result = await response.Content.ReadAsStringAsync ();
					Console.WriteLine ("result: {0}", result);
				}
			});
			t.Wait ();
		}
	}
}