在使用。net 4.5或。net Core时调用REST API

我推荐DalSoft。RestClient(注意:是我创建的)。原因是，因为它使用动态类型，您可以在一个流畅的调用中包装所有内容，包括序列化/反序列化。下面是一个工作的PUT示例:

dynamic client = new RestClient("http://jsonplaceholder.typicode.com");

var post = new Post { title = "foo", body = "bar", userId = 10 };

var result = await client.Posts(1).Put(post);

HTTP GET请求

    string api = this.configuration["getApiUrl"];//Read from Iconfiguration object injected
     public async Task<HttpResponseMessage> GetAsync(string api, ILogger log, params dynamic[] parameters)
            {
                log.LogInformation($"Get Token");
                var token = await GetTokenAsync(this.configuration["ClientId"], this.configuration["AppKey"]).ConfigureAwait(false);
                using (var client = new HttpClient())
                {
                  client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue(BearerTokenName, token);
                    var apiBaseUrl = this.configuration["BaseUrl"];
                   
                    client.BaseAddress = new Uri(apiBaseUrl);
                    var apiUrl = ConstructUrl(api, parameters);
                    var result = await client.GetAsync(apiUrl).ConfigureAwait(false);
    
                    if (result.StatusCode == System.Net.HttpStatusCode.OK)
                    {
                        return result;
                    }
                    else
                    {
                       throw new HttpResponseException(new HttpResponseMessage(result.StatusCode) { Content = new StringContent(result.ReasonPhrase) });
                    }
                }
            }
    

从HttpResponseMessage读取字符串，如下所示

     var client = await this.httpClientService.GetAsync(url, logger, Convert.ToInt32(Id, CultureInfo.InvariantCulture)).ConfigureAwait(false);
     var response = await client.Content.ReadAsStringAsync();

HTTP POST请求

     public async Task<string> PostAsync(string api, string contentValue, ILogger logger)
           {
               var token = await GetTokenAsync(this.configuration["ClientId"], this.configuration["AppKey"]).ConfigureAwait(false);
   
               using (var client = new HttpClient())
               {
                   client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue(BearerTokenName, token);
                   client.BaseAddress = new Uri(resource);
                   var content = new StringContent(contentValue, Encoding.UTF8, MediaTypeNames.Application.Json);
                   var result = await client.PostAsync(new Uri(api, UriKind.Relative), content).ConfigureAwait(false);
   
                   if (result.StatusCode == System.Net.HttpStatusCode.OK)
                   {
                       return await result.Content.ReadAsStringAsync();
                   }
                   else
                   {
                       throw new HttpResponseException(new HttpResponseMessage(result.StatusCode) { Content = new StringContent(result.ReasonPhrase) });
                   }
               }
           }

    var response = await this.httpClientService.PostAsync(this.configuration["getDetails"], content, this.configuration["ApiBaseUrl"], logger).ConfigureAwait(false);
      catch (System.Web.Http.HttpResponseException httpException)
                        {
                            if (httpException.Response.StatusCode == HttpStatusCode.Unauthorized)
                            {
                                logger.LogError($"Failed To Update", httpException);
                            }
                            else
                            {
                                throw;
                            }
                        }
    return response;

我使用Web API 2.0以这种简单的方式做到了这一点。您可以删除UseDefaultCredentials。我在自己的用例中使用了它。

List<YourObject> listObjects = new List<YourObject>();

string response = "";
using (var client = new WebClient() { UseDefaultCredentials = true })
{
     response = client.DownloadString(apiUrl);
}

listObjects = JsonConvert.DeserializeObject<List<YourObject>>(response);
return listObjects;

与此无关，我确定，但请使用块包装您的IDisposable对象，以确保适当的处置:

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

namespace ConsoleProgram
{
    public class Class1
    {
        private const string URL = "https://sub.domain.com/objects.json?api_key=123";
        private const string DATA = @"{""object"":{""name"":""Name""}}";

        static void Main(string[] args)
        {
            Class1.CreateObject();
        }

        private static void CreateObject()
        {
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(URL);
            request.Method = "POST";
            request.ContentType = "application/json";
            request.ContentLength = DATA.Length;
            using (Stream webStream = request.GetRequestStream())
            using (StreamWriter requestWriter = new StreamWriter(webStream, System.Text.Encoding.ASCII))
            {
                requestWriter.Write(DATA);
            }

            try
            {
                WebResponse webResponse = request.GetResponse();
                using (Stream webStream = webResponse.GetResponseStream() ?? Stream.Null)
                using (StreamReader responseReader = new StreamReader(webStream))
                {
                    string response = responseReader.ReadToEnd();
                    Console.Out.WriteLine(response);
                }
            }
            catch (Exception e)
            {
                Console.Out.WriteLine("-----------------");
                Console.Out.WriteLine(e.Message);
            }
        }
    }
}

以下是在c#中调用外部API的几种不同方式(2019年更新)。

.NET的内置方式:

webrequest和WebClient——冗长的api和微软的文档不是很容易理解 HttpClient - . net的最新产品&使用起来比上面提到的简单多了。

免费、开源的NuGet包，坦率地说，它比。net内置客户端有更好的开发体验:

ServiceStack。文本(1000个GitHub星，700万NuGet下载)(*)-快速，轻便和弹性。 RestSharp(6000个GitHub星，2300万NuGet下载)(*)-简单的REST和HTTP API客户端 Flurl (1700 GitHub星，300万NuGet下载)(*)-一个流畅，可移植，可测试的HTTP客户端库

上面所有的包都提供了很棒的开发体验(即简洁、简单的API)，并且维护得很好。

(*)截至2019年8月

示例:使用servicstack . text从伪Rest API获取Todo项。 其他库具有非常相似的语法。

class Program
{
    static void Main(string[] args)
    {
        // Fake rest API
        string url = "https://jsonplaceholder.typicode.com/todos/1";

        // GET data from API & map to POCO
        var todo =  url.GetJsonFromUrl().FromJson<Todo>();

        // Print the result to screen
        todo.PrintDump();
    }

    public class Todo
    {
        public int UserId { get; set; }
        public int Id { get; set; }
        public string Title { get; set; }
        public bool Completed { get; set; }
    }

}

在. net核心控制台应用程序中运行上述示例，产生以下输出。

使用NuGet安装这些包

Install-Package ServiceStack.Text, or

Install-Package RestSharp, or

Install-Package Flurl.Http

由于您使用的是Visual Studio 11 Beta，您将希望使用最新的和最好的。新的Web API包含了这方面的类。

参见HttpClient: http://wcf.codeplex.com/wikipage?title=WCF%20HTTP