建立和傳送 HTTP GET 請求

using System.Net;
using System.IO;

...

string requestUrl = "https://www.example.com/page.html";
HttpWebRequest request = HttpWebRequest.CreateHttp(requestUrl);

// Optionally, set properties of the HttpWebRequest, such as:
request.AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate;
request.Timeout = 2 * 60 * 1000; // 2 minutes, in milliseconds

// Submit the request, and get the response body.
string responseBodyFromRemoteServer;
using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
{
    using (StreamReader reader = new StreamReader(response.GetResponseStream()))
    {
        responseBodyFromRemoteServer = reader.ReadToEnd();
    }
}