查看Refit从. net调用REST服务。我发现它很容易使用:

改装:自动类型安全的REST库。net Core, Xamarin和 net Refit是一个很大程度上受到Square的Retrofit库启发的库 它把你的REST API变成一个活动接口:

public interface IGitHubApi {
        [Get("/users/{user}")]
        Task<User> GetUser(string user);
}

// The RestService class generates an implementation of IGitHubApi
// that uses HttpClient to make its calls:

var gitHubApi = RestService.For<IGitHubApi>("https://api.github.com");

var octocat = await gitHubApi.GetUser("octocat");

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;

ASP。NET Web API已经取代了前面提到的WCF Web API。

我想我应该发布一个更新的答案，因为这些回答大部分来自2012年初，当在谷歌上搜索“调用基于rest的服务c#”时，这个帖子是排名靠前的结果之一。

目前微软的指导方针是使用微软ASP。NET Web API客户端库来使用RESTful服务。这是一个NuGet包，Microsoft.AspNet.WebApi.Client。您需要将这个NuGet包添加到您的解决方案中。

下面是使用ASP实现示例时的外观。NET Web API客户端库:

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

namespace ConsoleProgram
{
    public class DataObject
    {
        public string Name { get; set; }
    }

    public class Class1
    {
        private const string URL = "https://sub.domain.com/objects.json";
        private string urlParameters = "?api_key=123";

        static void Main(string[] args)
        {
            HttpClient client = new HttpClient();
            client.BaseAddress = new Uri(URL);

            // Add an Accept header for JSON format.
            client.DefaultRequestHeaders.Accept.Add(
            new MediaTypeWithQualityHeaderValue("application/json"));

            // List data response.
            HttpResponseMessage response = client.GetAsync(urlParameters).Result;  // Blocking call! Program will wait here until a response is received or a timeout occurs.
            if (response.IsSuccessStatusCode)
            {
                // Parse the response body.
                var dataObjects = response.Content.ReadAsAsync<IEnumerable<DataObject>>().Result;  //Make sure to add a reference to System.Net.Http.Formatting.dll
                foreach (var d in dataObjects)
                {
                    Console.WriteLine("{0}", d.Name);
                }
            }
            else
            {
                Console.WriteLine("{0} ({1})", (int)response.StatusCode, response.ReasonPhrase);
            }

            // Make any other calls using HttpClient here.

            // Dispose once all HttpClient calls are complete. This is not necessary if the containing object will be disposed of; for example in this case the HttpClient instance will be disposed automatically when the application terminates so the following call is superfluous.
            client.Dispose();
        }
    }
}

如果您计划发出多个请求，您应该重用HttpClient实例。请参阅这个问题及其答案，以了解为什么在这种情况下没有在HttpClient实例上使用using语句的更多细节:HttpClient和HttpClientHandler必须在请求之间被处理吗?

有关更多细节，包括其他示例，请参见从。net客户端调用Web API (c#)

这篇博客文章也可能有用:使用HttpClient消费ASP。NET Web API REST服务

我的建议是使用RestSharp。您可以调用REST服务，并将它们转换为POCO对象，只需要很少的样板代码就可以解析响应。这不会解决您的特定错误，但它回答了如何调用REST服务的总体问题。必须更改代码才能使用它，这应该会在易用性和健壮性方面得到回报。不过这只是我的个人观点。

例子:

namespace RestSharpThingy
{
    using System;
    using System.Collections.Generic;
    using System.IO;
    using System.Linq;
    using System.Net;
    using System.Reflection;
    using RestSharp;

    public static class Program
    {
        public static void Main()
        {
            Uri baseUrl = new Uri("https://httpbin.org/");
            IRestClient client = new RestClient(baseUrl);
            IRestRequest request = new RestRequest("get", Method.GET) { Credentials = new NetworkCredential("testUser", "P455w0rd") };

            request.AddHeader("Authorization", "Bearer qaPmk9Vw8o7r7UOiX-3b-8Z_6r3w0Iu2pecwJ3x7CngjPp2fN3c61Q_5VU3y0rc-vPpkTKuaOI2eRs3bMyA5ucKKzY1thMFoM0wjnReEYeMGyq3JfZ-OIko1if3NmIj79ZSpNotLL2734ts2jGBjw8-uUgKet7jQAaq-qf5aIDwzUo0bnGosEj_UkFxiJKXPPlF2L4iNJSlBqRYrhw08RK1SzB4tf18Airb80WVy1Kewx2NGq5zCC-SCzvJW-mlOtjIDBAQ5intqaRkwRaSyjJ_MagxJF_CLc4BNUYC3hC2ejQDoTE6HYMWMcg0mbyWghMFpOw3gqyfAGjr6LPJcIly__aJ5__iyt-BTkOnMpDAZLTjzx4qDHMPWeND-TlzKWXjVb5yMv5Q6Jg6UmETWbuxyTdvGTJFzanUg1HWzPr7gSs6GLEv9VDTMiC8a5sNcGyLcHBIJo8mErrZrIssHvbT8ZUPWtyJaujKvdgazqsrad9CO3iRsZWQJ3lpvdQwucCsyjoRVoj_mXYhz3JK3wfOjLff16Gy1NLbj4gmOhBBRb8rJnUXnP7rBHs00FAk59BIpKLIPIyMgYBApDCut8V55AgXtGs4MgFFiJKbuaKxq8cdMYEVBTzDJ-S1IR5d6eiTGusD5aFlUkAs9NV_nFw");
            request.AddParameter("clientId", 123);

            IRestResponse<RootObject> response = client.Execute<RootObject>(request);

            if (response.IsSuccessful)
            {
                response.Data.Write();
            }
            else
            {
                Console.WriteLine(response.ErrorMessage);
            }

            Console.WriteLine();

            string path = Assembly.GetExecutingAssembly().Location;
            string name = Path.GetFileName(path);

            request = new RestRequest("post", Method.POST);
            request.AddFile(name, File.ReadAllBytes(path), name, "application/octet-stream");
            response = client.Execute<RootObject>(request);
            if (response.IsSuccessful)
            {
                response.Data.Write();
            }
            else
            {
                Console.WriteLine(response.ErrorMessage);
            }

            Console.ReadLine();
        }

        private static void Write(this RootObject rootObject)
        {
            Console.WriteLine("clientId: " + rootObject.args.clientId);
            Console.WriteLine("Accept: " + rootObject.headers.Accept);
            Console.WriteLine("AcceptEncoding: " + rootObject.headers.AcceptEncoding);
            Console.WriteLine("AcceptLanguage: " + rootObject.headers.AcceptLanguage);
            Console.WriteLine("Authorization: " + rootObject.headers.Authorization);
            Console.WriteLine("Connection: " + rootObject.headers.Connection);
            Console.WriteLine("Dnt: " + rootObject.headers.Dnt);
            Console.WriteLine("Host: " + rootObject.headers.Host);
            Console.WriteLine("Origin: " + rootObject.headers.Origin);
            Console.WriteLine("Referer: " + rootObject.headers.Referer);
            Console.WriteLine("UserAgent: " + rootObject.headers.UserAgent);
            Console.WriteLine("origin: " + rootObject.origin);
            Console.WriteLine("url: " + rootObject.url);
            Console.WriteLine("data: " + rootObject.data);
            Console.WriteLine("files: ");
            foreach (KeyValuePair<string, string> kvp in rootObject.files ?? Enumerable.Empty<KeyValuePair<string, string>>())
            {
                Console.WriteLine("\t" + kvp.Key + ": " + kvp.Value);
            }
        }
    }

    public class Args
    {
        public string ClientId { get; set; }
    }

    public class Headers
    {
        public string Accept { get; set; }

        public string AcceptEncoding { get; set; }

        public string AcceptLanguage { get; set; }

        public string Authorization { get; set; }

        public string Connection { get; set; }

        public string Dnt { get; set; }

        public string Host { get; set; }

        public string Origin { get; set; }

        public string Referer { get; set; }

        public string UserAgent { get; set; }
    }

    public class RootObject
    {
        public Args args { get; set; }

        public Headers Headers { get; set; }

        public string Origin { get; set; }

        public string Url { get; set; }

        public string Data { get; set; }

        public Dictionary<string, string> Files { get; set; }
    }
}

第一步是为HTTP客户机创建helper类。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Threading.Tasks;

namespace callApi.Helpers
{
    public class CallApi
    {
        private readonly Uri BaseUrlUri;
        private HttpClient client = new HttpClient();

        public CallApi(string baseUrl)
        {
            BaseUrlUri = new Uri(baseUrl);
            client.BaseAddress = BaseUrlUri;
            client.DefaultRequestHeaders.Accept.Clear();
            client.DefaultRequestHeaders.Accept.Add(
                new MediaTypeWithQualityHeaderValue("application/json"));
        }

        public HttpClient getClient()
        {
            return client;
        }

        public HttpClient getClientWithBearer(string token)
        {
            client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
            return client;
        }
    }
}

然后可以在代码中使用这个类。

这是如何使用上面的类调用不带承载的REST API的示例。

// GET API/values
[HttpGet]
public async Task<ActionResult<string>> postNoBearerAsync(string email, string password,string baseUrl, string action)
{
    var request = new LoginRequest
    {
        email = email,
        password = password
    };

    var callApi = new CallApi(baseUrl);
    var client = callApi.getClient();
    HttpResponseMessage response = await client.PostAsJsonAsync(action, request);
    if (response.IsSuccessStatusCode)
        return Ok(await response.Content.ReadAsAsync<string>());
    else
        return NotFound();
}

这是一个如何调用需要承载的REST API的示例。

// GET API/values
[HttpGet]
public async Task<ActionResult<string>> getUseBearerAsync(string token, string baseUrl, string action)
{
    var callApi = new CallApi(baseUrl);
    var client = callApi.getClient();
    client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
    HttpResponseMessage response = await client.GetAsync(action);
    if (response.IsSuccessStatusCode)
    {
        return Ok(await response.Content.ReadAsStringAsync());
    }
    else
        return NotFound();
}

如果您想查看它如何工作的工作示例，还可以参考下面的存储库。

https://github.com/mokh223/callApi

我们已经开始使用地下酒吧了。这很棒:

https://github.com/jonnii/SpeakEasy

// create a client
var client = HttpClient.Create("http://example.com/api");
    
// get some companies!
var companies = client.Get("companies").OnOk().As<List<Company>>();
  
// upload a company, with validation error support
client.Post(company, "companies")
    .On(HttpStatusCode.BadRequest, (List<ValidationError> errors) => {
        Console.WriteLine("Ruh Roh, you have {0} validation errors", errors.Count());
    })
    .On(HttpStatusCode.Created, () => Console.WriteLine("Holy moly you win!"));
    
// update a company
client.Put(company, "company/:id", new { id = "awesome-sauce" })
    .OnOk(() => Console.WriteLine("Company updated"));
        
// run a search
client.Get("images/:category", new { category = "cats", breed = "omg the cutest", size = "kittens" })
    .OnOk().As<List<Image>>();
    
// make an asynchronous request
var response = await client.GetAsync("companies/:id", new { id = 5 })
response.OnOk(UpdateCompaniesCallback)