Jak wykonać żądanie HTTP POST

Istnieje kilka sposobów na wykonanie żądań HTTP GET i POST:

Metoda A: HttpClient (preferowana)

To jest wrapper wokół HttpWebRequest. Porównaj z WebClient.

Dostępne w: .NET Framework 4.5+, .NET Standard 1.1+, .NET Core 1.0+ .

Obecnie preferowane podejście. Asynchroniczne. Wersja przenośna dla innych platform dostępna przez NuGet.

using System.Net.Http;

Konfiguracja

Jest zalecane, aby utworzyć jeden HttpClient na cały czas działania aplikacji i udostępnić go.

private static readonly HttpClient client = new HttpClient();

Zobacz HttpClientFactory dla rozwiązania Dependency Injection.

• 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");

Metoda B: Biblioteki stron trzecich

• RestSharp

Sprawdzona i przetestowana biblioteka do interakcji z interfejsami API REST. Przenośna. Dostępna przez NuGet.

• Flurl.Http

Nowsza biblioteka z płynnym API i pomocnikami do testowania. HttpClient pod maską. Przenośna. Dostępna przez NuGet.

    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();

Metoda C: HttpWebRequest (Nie zalecana dla nowych prac)

Dostępne w: .NET Framework 1.1+, .NET Standard 2.0+, .NET Core 1.0+.

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();

Metoda D: WebClient (Nie zalecane dla nowych prac)

To jest wrapper wokół HttpWebRequest. Porównaj z HttpClient.

Dostępny w: .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");
    }

Proste żądanie GET

using System.Net;

...

using (var wb = new WebClient())
{
    var response = wb.DownloadString(url);
}

Proste żądanie POST

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

...

using (var wb = new WebClient())
{
    var data = new NameValueCollection();
    data["username"] = "myUser";
    data["password"] = "myPassword";

    var response = wb.UploadValues(url, "POST", data);
    string responseInString = Encoding.UTF8.GetString(response);
}

MSDN ma próbkę.

using System;
using System.IO;
using System.Net;
using System.Text;

namespace Examples.System.Net
{
    public class WebRequestPostExample
    {
        public static void Main()
        {
            // Create a request using a URL that can receive a post. 
            WebRequest request = WebRequest.Create("http://www.contoso.com/PostAccepter.aspx");
            // Set the Method property of the request to POST.
            request.Method = "POST";
            // Create POST data and convert it to a byte array.
            string postData = "This is a test that posts this string to a Web server.";
            byte[] byteArray = Encoding.UTF8.GetBytes(postData);
            // Set the ContentType property of the WebRequest.
            request.ContentType = "application/x-www-form-urlencoded";
            // Set the ContentLength property of the WebRequest.
            request.ContentLength = byteArray.Length;
            // Get the request stream.
            Stream dataStream = request.GetRequestStream();
            // Write the data to the request stream.
            dataStream.Write(byteArray, 0, byteArray.Length);
            // Close the Stream object.
            dataStream.Close();
            // Get the response.
            WebResponse response = request.GetResponse();
            // Display the status.
            Console.WriteLine(((HttpWebResponse)response).StatusDescription);
            // Get the stream containing content returned by the server.
            dataStream = response.GetResponseStream();
            // Open the stream using a StreamReader for easy access.
            StreamReader reader = new StreamReader(dataStream);
            // Read the content.
            string responseFromServer = reader.ReadToEnd();
            // Display the content.
            Console.WriteLine(responseFromServer);
            // Clean up the streams.
            reader.Close();
            dataStream.Close();
            response.Close();
        }
    }
}