.NET HttpClient。如何发布字符串值？

Question

如何使用 C# 和 HttpClient 创建以下 POST 请求：

我的 WEB API 服务需要这样的请求：

[ActionName("exist")]
[HttpPost]
public bool CheckIfUserExist([FromBody] string login)
{           
    return _membershipProvider.CheckIfExist(login);
}

Answer 1

using System;
using System.Collections.Generic;
using System.Net.Http;

class Program
{
    static void Main(string[] args)
    {
        Task.Run(() => MainAsync());
        Console.ReadLine();
    }

    static async Task MainAsync()
    {
        using (var client = new HttpClient())
        {
            client.BaseAddress = new Uri("http://localhost:6740");
            var content = new FormUrlEncodedContent(new[]
            {
                new KeyValuePair<string, string>("", "login")
            });
            var result = await client.PostAsync("/api/Membership/exists", content);
            string resultContent = await result.Content.ReadAsStringAsync();
            Console.WriteLine(resultContent);
        }
    }
}

Answer 2

以下是同步调用的示例，但您可以使用 await-sync 轻松更改为异步：

var pairs = new List<KeyValuePair<string, string>>
            {
                new KeyValuePair<string, string>("login", "abc")
            };

var content = new FormUrlEncodedContent(pairs);

var client = new HttpClient {BaseAddress = new Uri("http://localhost:6740")};

    // call sync
var response = client.PostAsync("/api/membership/exist", content).Result; 
if (response.IsSuccessStatusCode)
{
}

Answer 3

Here 我发现这篇文章是使用JsonConvert.SerializeObject() 和StringContent() 发送帖子请求到HttpClient.PostAsync 数据

static async Task Main(string[] args)
{
    var person = new Person();
    person.Name = "John Doe";
    person.Occupation = "gardener";

    var json = Newtonsoft.Json.JsonConvert.SerializeObject(person);
    var data = new System.Net.Http.StringContent(json, Encoding.UTF8, "application/json");

    var url = "https://httpbin.org/post";
    using var client = new HttpClient();

    var response = await client.PostAsync(url, data);

    string result = response.Content.ReadAsStringAsync().Result;
    Console.WriteLine(result);
}

Answer 4

asp.net 网站上有一篇关于您的问题的文章。我希望它可以帮助你。

如何用asp net调用api

http://www.asp.net/web-api/overview/advanced/calling-a-web-api-from-a-net-client

这是文章 POST 部分的一小部分

以下代码发送一个 POST 请求，其中包含 JSON 格式的 Product 实例：

// HTTP POST
var gizmo = new Product() { Name = "Gizmo", Price = 100, Category = "Widget" };
response = await client.PostAsJsonAsync("api/products", gizmo);
if (response.IsSuccessStatusCode)
{
    // Get the URI of the created resource.
    Uri gizmoUrl = response.Headers.Location;
}

Answer 5

你可以这样做

HttpWebRequest req = (HttpWebRequest)WebRequest.Create("http://localhost:6740/api/Membership/exist");

req.Method = "POST";
req.ContentType = "application/x-www-form-urlencoded";         
req.ContentLength = 6;

StreamWriter streamOut = new StreamWriter(req.GetRequestStream(), System.Text.Encoding.ASCII);
streamOut.Write(strRequest);
streamOut.Close();
StreamReader streamIn = new StreamReader(req.GetResponse().GetResponseStream());
string strResponse = streamIn.ReadToEnd();
streamIn.Close();

然后 strReponse 应该包含你的 web 服务返回的值