关于c＃：如何发出HTTP POST Web请求


How to make HTTP POST web request

canonical：我如何使用POST方法发出HTTP请求并发送一些数据？我可以执行GET请求，但不知道如何生成POST。

有几种方法可以执行http GET和POST请求：

方法A:httpclient

在.NET Framework 4.5+、.NET Standard 1.1+、.NET Core 1.0中提供+

目前首选的方法。异步的。其他平台的便携式版本可通过Nuget获得。

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using System.Net.Http;

安装程序

建议为应用程序的生命周期实例化一个HttpClient，并共享它。

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private static readonly HttpClient client = new HttpClient();

柱

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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();

得到

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

方法B：第三方图书馆

赖斯塔尔

尝试并测试了与RESTAPI交互的库。便携式。通过Nuget提供。

Flurl

更新的库拥有流畅的API和测试助手。引擎盖下的HTTPClient。便携式。通过Nuget提供。

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using Flurl.Http;

柱

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

得到

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

方法C：传统

可用于：.NET Framework 1.1+、.NET Standard 2.0+、.NET Core 1.0+

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

柱

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

var postData ="thing1=hello";
    postData +="&thing2=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();

得到

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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(现在也是传统方法)

可用于：.NET Framework 1.1+、.NET Standard 2.0+、.NET Core 2.0+

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

柱

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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);
}

得到

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using (var client = new WebClient())
{
    var responseString = client.DownloadString("http://www.example.com/recepticle.aspx");
}
相关讨论

简单获取请求

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using System.Net;

...

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

简单的POST请求

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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);
}
相关讨论

msdn有一个样本。

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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();
        }
    }
}
相关讨论

这是以JSON格式发送/接收数据的完整工作示例，我使用了VS2013 Express版本

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using System;
using System.Collections.Generic;
using System.Data;
using System.Data.OleDb;
using System.IO;
using System.Linq;
using System.Net.Http;
using System.Text;
using System.Threading.Tasks;
using System.Web.Script.Serialization;

namespace ConsoleApplication1
{
    class Customer
    {
        public string Name { get; set; }
        public string Address { get; set; }
        public string Phone { get; set; }
    }

    public class Program
    {
        private static readonly HttpClient _Client = new HttpClient();
        private static JavaScriptSerializer _Serializer = new JavaScriptSerializer();

        static void Main(string[] args)
        {
            Run().Wait();
        }

        static async Task Run()
        {
            string url ="http://www.example.com/api/Customer";
            Customer cust = new Customer() { Name ="Example Customer", Address ="Some example address", Phone ="Some phone number" };
            var json = _Serializer.Serialize(cust);
            var response = await Request(HttpMethod.Post, url, json, new Dictionary<string, string>());
            string responseText = await response.Content.ReadAsStringAsync();

            List<YourCustomClassModel> serializedResult = _Serializer.Deserialize<List<YourCustomClassModel>>(responseText);

            Console.WriteLine(responseText);
            Console.ReadLine();
        }

        /// <summary>
        /// Makes an async HTTP Request
        /// </summary>
        /// <param name="pMethod">Those methods you know: GET, POST, HEAD, etc...</param>
        /// <param name="pUrl">Very predictable...</param>
        /// <param name="pJsonContent">String data to POST on the server</param>
        /// <param name="pHeaders">If you use some kind of Authorization you should use this</param>
        /// <returns></returns>
        static async Task<HttpResponseMessage> Request(HttpMethod pMethod, string pUrl, string pJsonContent, Dictionary<string, string> pHeaders)
        {
            var httpRequestMessage = new HttpRequestMessage();
            httpRequestMessage.Method = pMethod;
            httpRequestMessage.RequestUri = new Uri(pUrl);
            foreach (var head in pHeaders)
            {
                httpRequestMessage.Headers.Add(head.Key, head.Value);
            }
            switch (pMethod.Method)
            {
                case"POST":
                    HttpContent httpContent = new StringContent(pJsonContent, Encoding.UTF8,"application/json");
                    httpRequestMessage.Content = httpContent;
                    break;

            }

            return await _Client.SendAsync(httpRequestMessage);
        }
    }
}

这里有一些很好的答案。让我用一种不同的方法来设置WebClient()的头部。我还将向您演示如何设置API密钥。

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        var client = new WebClient();
        string credentials = Convert.ToBase64String(Encoding.ASCII.GetBytes(userName +":" + passWord));
        client.Headers[HttpRequestHeader.Authorization] = $"Basic {credentials}";
        //If you have your data stored in an object serialize it into json to pass to the webclient with Newtonsoft's JsonConvert
        var encodedJson = JsonConvert.SerializeObject(newAccount);

        client.Headers.Add($"x-api-key:{ApiKey}");
        client.Headers.Add("Content-Type:application/json");
        try
        {
            var response = client.UploadString($"{apiurl}", encodedJson);
            //if you have a model to deserialize the json into Newtonsoft will help bind the data to the model, this is an extremely useful trick for GET calls when you have a lot of data, you can strongly type a model and dump it into an instance of that class.
            Response response1 = JsonConvert.DeserializeObject<Response>(response);

当使用windows.web.http命名空间时，对于post而不是formurlencodedcontent，我们编写httpformurlencodedcontent。响应也是httpResponseMessage的类型。其余的都是伊万穆拉夫斯基写下的。

简单的(一行程序，没有错误检查，没有等待响应)解决方案

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(new WebClient()).UploadStringAsync(new Uri(Address), dataString);?

小心使用！

相关讨论

您可以使用IEnterprise.easy-http，因为它内置了类解析和查询构建：

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await new RequestBuilder<ExampleObject>()
.SetHost("https://httpbin.org")
.SetContentType(ContentType.Application_Json)
.SetType(RequestType.Post)
.SetModelToSerialize(dto)
.Build()
.Execute();

我是这个库的作者，所以请随意提问或在Github中检查代码。

相关讨论

此解决方案只使用标准.NET调用。

测试：

  • 在企业WPF应用程序中使用。使用async/await避免阻塞UI。
  • 与.NET 4.5+兼容。
  • 无参数测试(需要在后台"获取")。
  • 使用参数进行测试(需要在后台"发布")。
  • 使用谷歌等标准网页进行测试。
  • 使用基于Java的内部WebService进行测试。

参考文献：

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// Add a Reference to the assembly System.Web

代码：

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using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Net;
using System.Net.Http;
using System.Threading.Tasks;
using System.Web;

private async Task<WebResponse> CallUri(string url, TimeSpan timeout)
{
    var uri = new Uri(url);
    NameValueCollection rawParameters = HttpUtility.ParseQueryString(uri.Query);
    var parameters = new Dictionary<string, string>();
    foreach (string p in rawParameters.Keys)
    {
        parameters[p] = rawParameters[p];
    }

    var client = new HttpClient { Timeout = timeout };
    HttpResponseMessage response;
    if (parameters.Count == 0)
    {
        response = await client.GetAsync(url);
    }
    else
    {
        var content = new FormUrlEncodedContent(parameters);
        string urlMinusParameters = uri.OriginalString.Split('?')[0]; // Parameters always follow the '?' symbol.
        response = await client.PostAsync(urlMinusParameters, content);
    }
    var responseString = await response.Content.ReadAsStringAsync();

    return new WebResponse(response.StatusCode, responseString);
}

private class WebResponse
{
    public WebResponse(HttpStatusCode httpStatusCode, string response)
    {
        this.HttpStatusCode = httpStatusCode;
        this.Response = response;
    }
    public HttpStatusCode HttpStatusCode { get; }
    public string Response { get; }
}

不带参数调用(在后台使用"get")：

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 var timeout = TimeSpan.FromSeconds(300);
 WebResponse response = await this.CallUri("http://www.google.com/", timeout);
 if (response.HttpStatusCode == HttpStatusCode.OK)
 {
     Console.Write(response.Response); // Print HTML.
 }

要使用参数调用(在后台使用"post")：

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 var timeout = TimeSpan.FromSeconds(300);
 WebResponse response = await this.CallUri("http://example.com/path/to/page?name=ferret&color=purple", timeout);
 if (response.HttpStatusCode == HttpStatusCode.OK)
 {
     Console.Write(response.Response); // Print HTML.
 }

如果您喜欢流畅的API，可以使用tiny.restclient，它在nuget上提供

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var client = new TinyRestClient(new HttpClient(),"http://MyAPI.com/api");
// POST
 var city = new City() { Name ="Paris" , Country ="France"};
// With content
var response = await client.PostRequest("City", city).
                ExecuteAsync<bool>();

希望有帮助！