使用C#控制台应用程序创建HTTP POST请求并接收响应

Question

我需要将数据发布到一个URL（https://somesite.com）以基于我发布的参数在响应流中下载文件。 如何使用C#控制台应用程序实现这一点？

参数: 文件名， 用户ID， 密码， 类型

- user470310

Answer 1

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.IO;

namespace WebserverInteractionClassLibrary
{
    public class RequestManager
    {
        public string LastResponse { protected set; get; }

        CookieContainer cookies = new CookieContainer();

        internal string GetCookieValue(Uri SiteUri,string name)
        {
            Cookie cookie = cookies.GetCookies(SiteUri)[name];
            return (cookie == null) ? null : cookie.Value;
        }

        public string GetResponseContent(HttpWebResponse response)
        {
            if (response == null)
            {
                throw new ArgumentNullException("response");
            }
            Stream dataStream = null;
            StreamReader reader = null;
            string responseFromServer = null;

            try
            {
                // Get the stream containing content returned by the server.
                dataStream = response.GetResponseStream();
                // Open the stream using a StreamReader for easy access.
                reader = new StreamReader(dataStream);
                // Read the content.
                responseFromServer = reader.ReadToEnd();
                // Cleanup the streams and the response.
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
            finally
            {                
                if (reader != null)
                {
                    reader.Close();
                }
                if (dataStream != null)
                {
                    dataStream.Close();
                }
                response.Close();
            }
            LastResponse = responseFromServer;
            return responseFromServer;
        }

        public HttpWebResponse SendPOSTRequest(string uri, string content, string login, string password, bool allowAutoRedirect)
        {
            HttpWebRequest request = GeneratePOSTRequest(uri, content, login, password, allowAutoRedirect);
            return GetResponse(request);
        }

        public HttpWebResponse SendGETRequest(string uri, string login, string password, bool allowAutoRedirect)
        {
            HttpWebRequest request = GenerateGETRequest(uri, login, password, allowAutoRedirect);
            return GetResponse(request);
        }

        public HttpWebResponse SendRequest(string uri, string content, string method, string login, string password, bool allowAutoRedirect)
        {
            HttpWebRequest request = GenerateRequest(uri, content, method, login, password, allowAutoRedirect);
            return GetResponse(request);
        }

        public HttpWebRequest GenerateGETRequest(string uri, string login, string password, bool allowAutoRedirect)
        {
            return GenerateRequest(uri, null, "GET", null, null, allowAutoRedirect);
        }

        public HttpWebRequest GeneratePOSTRequest(string uri, string content, string login, string password, bool allowAutoRedirect)
        {
            return GenerateRequest(uri, content, "POST", null, null, allowAutoRedirect);
        }

        internal HttpWebRequest GenerateRequest(string uri, string content, string method, string login, string password, bool allowAutoRedirect)
        {
            if (uri == null)
            {
                throw new ArgumentNullException("uri");
            }
            // Create a request using a URL that can receive a post. 
            HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(uri);
            // Set the Method property of the request to POST.
            request.Method = method;
            // Set cookie container to maintain cookies
            request.CookieContainer = cookies;
            request.AllowAutoRedirect = allowAutoRedirect;
            // If login is empty use defaul credentials
            if (string.IsNullOrEmpty(login))
            {
                request.Credentials = CredentialCache.DefaultNetworkCredentials;
            }
            else
            {
                request.Credentials = new NetworkCredential(login, password);
            }
            if (method == "POST")
            {
                // Convert POST data to a byte array.
                byte[] byteArray = Encoding.UTF8.GetBytes(content);
                // 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();
            }
            return request;
        }

        internal HttpWebResponse GetResponse(HttpWebRequest request)
        {
            if (request == null)
            {
                throw new ArgumentNullException("request");
            }
            HttpWebResponse response = null;
            try
            {
                response = (HttpWebResponse)request.GetResponse();                
                cookies.Add(response.Cookies);                
                // Print the properties of each cookie.
                Console.WriteLine("\nCookies: ");
                foreach (Cookie cook in cookies.GetCookies(request.RequestUri))
                {
                    Console.WriteLine("Domain: {0}, String: {1}", cook.Domain, cook.ToString());
                }
            }
            catch (WebException ex)
            {
                Console.WriteLine("Web exception occurred. Status code: {0}", ex.Status);
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
            return response;
        }

    }
}

- cement

---

看起来 GenerateRequest 方法忽略了它的 allowAutoRedirect 参数值，并且总是使用 false 值？ - Jon Schneider

Answer 2

请查看 System.Net.WebClient 类，它可用于发出请求和处理其响应，以及下载文件。有关更多信息，请访问以下链接：http://www.hanselman.com/blog/HTTPPOSTsAndHTTPGETsWithWebClientAndCAndFakingAPostBack.aspx 和 http://msdn.microsoft.com/en-us/library/system.net.webclient(VS.90).aspx。

- STW

Answer 3

您可以在 .net 中简单使用 "HttpWebRequest" 和 "HttpWebResponse" 类实现此功能。

下面是我编写的演示如何轻松实现此功能的示例控制台应用程序。

using System;
using System.Collections.Generic;
using System.Text;
using System.Net;
using System.IO;

namespace Test
{
    class Program
    {
        static void Main(string[] args)
        {
            string url = "www.somewhere.com";       
            string fileName = @"C:\output.file";

            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
            request.Timeout = 5000;

            try
            {
                using (WebResponse response = (HttpWebResponse)request.GetResponse())
                {
                    using (FileStream stream = new FileStream(fileName, FileMode.Create, FileAccess.Write))
                    {
                        byte[] bytes = ReadFully(response.GetResponseStream());

                        stream.Write(bytes, 0, bytes.Length);
                    }
                }
            }
            catch (WebException)
            {
                Console.WriteLine("Error Occured");
            }
        }

        public static byte[] ReadFully(Stream input)
        {
            byte[] buffer = new byte[16 * 1024];
            using (MemoryStream ms = new MemoryStream())
            {
                int read;
                while ((read = input.Read(buffer, 0, buffer.Length)) > 0)
                {
                    ms.Write(buffer, 0, read);
                }
                return ms.ToArray();
            }
        }
    }
}

享受吧！

- Doug

---

谢谢。我认为您的代码是用于下载，但我还需要了解如何将数据提交到远程服务器。 - user470310

我需要向服务器发送一个请求XML并读取响应。我该如何发送请求？我需要将其与URL连接起来吗？例如：网站URL：http://remoteserver.com要发送的XML：<root><request v1="abc" v2="123" /></root> - yaronkl

Answer 4

HttpWebRequest request =(HttpWebRequest)WebRequest.Create("some url");
request.Method = "POST";
request.ContentType = "application/x-www-form-urlencoded";
request.UserAgent = "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 7.1; Trident/5.0)";
request.Accept = "/";
request.UseDefaultCredentials = true;
request.Proxy.Credentials = System.Net.CredentialCache.DefaultCredentials;
doc.Save(request.GetRequestStream());
HttpWebResponse resp = request.GetResponse() as HttpWebResponse;

希望能对您有所帮助。

- Manish sharma

Answer 5

建议使用 net 4.5 中引入的 System.Net.Http.HttpClient，而不是使用 System.Net.WebClient。这样可以使您的生活更加轻松。此外，微软也推荐在这篇文章中使用 HttpClient。

http://msdn.microsoft.com/en-us/library/system.net.webclient(VS.90).aspx

下面是一个示例：

var client = new HttpClient();
var content = new MultipartFormDataContent
{
     { new StringContent("myUserId"), "userid"},
     { new StringContent("myFileName"), "filename"},
     { new StringContent("myPassword"), "password"},
     { new StringContent("myType"), "type"}
};

var responseMessage = await client.PostAsync("some url", content);        
var stream = await responseMessage.Content.ReadAsStreamAsync();

- OwnBlood

---

回答不错，但缺少一个有价值的例子。也许可以添加一个代码片段，展示如何使用 HttpClient 来完成它？ - Prolog

@Prolog 刚刚添加了一个例子。 - OwnBlood