这是我到目前为止的代码:
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;
StreamWriter requestWriter = new StreamWriter(request.GetRequestStream(), System.Text.Encoding.ASCII);
requestWriter.Write(DATA);
requestWriter.Close();
try {
WebResponse webResponse = request.GetResponse();
Stream webStream = webResponse.GetResponseStream();
StreamReader responseReader = new StreamReader(webStream);
string response = responseReader.ReadToEnd();
Console.Out.WriteLine(response);
responseReader.Close();
} catch (Exception e) {
Console.Out.WriteLine("-----------------");
Console.Out.WriteLine(e.Message);
}
}
}
问题是我认为异常块正在被触发(因为当我删除try-catch时，我得到一个服务器错误(500)消息。但是我没有看到控制台。我在catch block里放了几行。
我的控制台:
The thread 'vshost.NotifyLoad' (0x1a20) has exited with code 0 (0x0).
The thread '<No Name>' (0x1988) has exited with code 0 (0x0).
The thread 'vshost.LoadReference' (0x1710) has exited with code 0 (0x0).
'ConsoleApplication1.vshost.exe' (Managed (v4.0.30319)): Loaded 'c:\users\l. preston sego iii\documents\visual studio 11\Projects\ConsoleApplication1\ConsoleApplication1\bin\Debug\ConsoleApplication1.exe', Symbols loaded.
'ConsoleApplication1.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Configuration\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Configuration.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
A first chance exception of type 'System.Net.WebException' occurred in System.dll
The thread 'vshost.RunParkingWindow' (0x184c) has exited with code 0 (0x0).
The thread '<No Name>' (0x1810) has exited with code 0 (0x0).
The program '[2780] ConsoleApplication1.vshost.exe: Program Trace' has exited with code 0 (0x0).
The program '[2780] ConsoleApplication1.vshost.exe: Managed (v4.0.30319)' has exited with code 0 (0x0).
GET:
// GET JSON Response
public WeatherResponseModel GET(string url) {
WeatherResponseModel model = new WeatherResponseModel();
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
try {
WebResponse response = request.GetResponse();
using(Stream responseStream = response.GetResponseStream()) {
StreamReader reader = new StreamReader(responseStream, Encoding.UTF8);
model = JsonConvert.DeserializeObject < WeatherResponseModel > (reader.ReadToEnd());
}
} catch (WebException ex) {
WebResponse errorResponse = ex.Response;
using(Stream responseStream = errorResponse.GetResponseStream()) {
StreamReader reader = new StreamReader(responseStream, Encoding.GetEncoding("utf-8"));
String errorText = reader.ReadToEnd();
// Log errorText
}
throw;
}
return model;
}
职位:
// POST a JSON string
void POST(string url, string jsonContent) {
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
request.Method = "POST";
System.Text.UTF8Encoding encoding = new System.Text.UTF8Encoding();
Byte[]byteArray = encoding.GetBytes(jsonContent);
request.ContentLength = byteArray.Length;
request.ContentType = @ "application/json";
using(Stream dataStream = request.GetRequestStream()) {
dataStream.Write(byteArray, 0, byteArray.Length);
}
long length = 0;
try {
using(HttpWebResponse response = (HttpWebResponse)request.GetResponse()) {
// Got response
length = response.ContentLength;
}
} catch (WebException ex) {
WebResponse errorResponse = ex.Response;
using(Stream responseStream = errorResponse.GetResponseStream()) {
StreamReader reader = new StreamReader(responseStream, Encoding.GetEncoding("utf-8"));
String errorText = reader.ReadToEnd();
// Log errorText
}
throw;
}
}
注意:为了序列化和反序列化JSON，我使用了Newtonsoft。Json NuGet包。
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
此处标记的答案建议直接使用HttpClient并销毁它。这可能会起作用，但是如果你没有正确地使用HttpClient，它很容易遇到问题。
如果您打算使用HttpClient，最好将HttpClient的创建/处理交给使用工厂模式的第三方库。RestClient。Net就是这样一个库。
它带有一个非常基本的HttpClient工厂，这样你就不会碰到套接字耗尽的问题，
public class DefaultHttpClientFactory : IHttpClientFactory, IDisposable
{
#region Fields
private bool disposed;
private readonly ConcurrentDictionary<string, Lazy<HttpClient>> _httpClients;
private readonly Func<string, Lazy<HttpClient>> _createClientFunc;
#endregion
#region Constructor
public DefaultHttpClientFactory() : this(null)
{
}
public DefaultHttpClientFactory(Func<string, Lazy<HttpClient>> createClientFunc)
{
_createClientFunc = createClientFunc;
_httpClients = new ConcurrentDictionary<string, Lazy<HttpClient>>();
if (_createClientFunc != null) return;
_createClientFunc = name =>
{
return new Lazy<HttpClient>(() => new HttpClient(), LazyThreadSafetyMode.ExecutionAndPublication);
};
}
#endregion
#region Implementation
public HttpClient CreateClient(string name)
{
if (name == null)
{
throw new ArgumentNullException(nameof(name));
}
return _httpClients.GetOrAdd(name, _createClientFunc).Value;
}
public void Dispose()
{
if (disposed) return;
disposed = true;
foreach (var name in _httpClients.Keys)
{
_httpClients[name].Value.Dispose();
}
}
#endregion
}
但是微软的IHttpClientFactory实现也可以用于最新和最好的:
var serviceCollection = new ServiceCollection();
var baseUri = new Uri("http://www.test.com");
serviceCollection.AddSingleton(typeof(ISerializationAdapter), typeof(NewtonsoftSerializationAdapter));
serviceCollection.AddSingleton(typeof(ILogger), typeof(ConsoleLogger));
serviceCollection.AddSingleton(typeof(IClient), typeof(Client));
serviceCollection.AddDependencyInjectionMapping();
serviceCollection.AddTransient<TestHandler>();
//Make sure the HttpClient is named the same as the Rest Client
serviceCollection.AddSingleton<IClient>(x => new Client(name: clientName, httpClientFactory: x.GetRequiredService<IHttpClientFactory>()));
serviceCollection.AddHttpClient(clientName, (c) => { c.BaseAddress = baseUri; })
.AddHttpMessageHandler<TestHandler>();
var serviceProvider = serviceCollection.BuildServiceProvider();
var client = serviceProvider.GetService<IClient>();
await client.GetAsync<object>();
RestClient。Net考虑了依赖注入、模拟、IoC容器、单元可测试性，最重要的是速度快。我四处寻找，唯一的另一个客户端，似乎工作在类似的能力是flul . http。
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; }
}
}
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
