C# HttpClient使用 网络(一)

一、异步调用web服务  GetAsync()

 1  static void Main(string[] args)
 2         {
 3             Console.WriteLine("In main before call to GetData!");
 4             GetData();
 5             Console.WriteLine("Back in main after call to GetData!");
 6             Console.ReadKey();
 7         }
 8         static  async void GetData()
 9         {
10             HttpClient httpClient = new HttpClient();
11             HttpResponseMessage response = null;
12          
13             response = await httpClient.GetAsync("http://www.baidu.com");
14             if(response.IsSuccessStatusCode)
15             {
16                 Console.WriteLine("Response status Code :" + response.StatusCode + " " + response.ReasonPhrase);
17                 string responseBodyAsText = response.Content.ReadAsStringAsync().Result;
18                 Console.WriteLine("Received payload of " + responseBodyAsText.Length + " characters");
19                 Console.WriteLine(responseBodyAsText);
20             }
21         }

二、设置或改变请求标题

 1    static void Main(string[] args)
 2         {
 3             GetData2();
 4             Console.ReadKey();
 5         }
 6 
 7 static  void GetData2()
 8         {
 9             HttpClient httpClient = new HttpClient();
10             HttpResponseMessage response = null;
11             httpClient.DefaultRequestHeaders.Add("Accept", "application/json;odata=verbose");
12             Console.WriteLine("Request Headers:");
13             EnumerateHeaders(httpClient.DefaultRequestHeaders);
14             Console.WriteLine();
15            response =  httpClient.GetAsync("http://www.baidu.com").Result;
16             if (response.IsSuccessStatusCode)
17             {
18                 Console.WriteLine("Response Headers:");
19                 EnumerateHeaders(response.Headers);
20             }
21         }
22         private static void EnumerateHeaders(HttpHeaders headers)
23         {
24             foreach (var header in headers)
25             {
26                 var value = "";
27                 foreach (var val in header.Value)
28                 {
29                     value = val + " ";
30                 }
31                 Console.WriteLine("Header: " + header.Key + " Value: " + value);
32             }
33         }

三、HttpMessageHandler

 1 class Program
 2     {
 3 
 4         static void Main(string[] args)
 5         {
 6             GetData();
 7             Console.ReadKey();
 8         }
 9 
10         private static void GetData()
11         {
12             HttpClient httpClient = new HttpClient(new MessageHandler("error"));
13             HttpResponseMessage response = null;
14             Console.WriteLine();
15             response = httpClient.GetAsync("http://services.odata.org/Northwind/Northwind.svc/Regions").Result;
16             Console.WriteLine(response.StatusCode);
17         }
18     }
19 
20     public class MessageHandler : HttpClientHandler
21     {
22         string displayMessage = "";
23         public MessageHandler(string message)
24         {
25             displayMessage = message;
26         }
27 
28         protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, System.Threading.CancellationToken cancellationToken)
29         {
30             Console.WriteLine("In DisplayMessageHandler " + displayMessage);
31             if (displayMessage == "error")
32             {
33                 var response = new HttpResponseMessage(System.Net.HttpStatusCode.BadRequest);
34                 var tsc = new TaskCompletionSource<HttpResponseMessage>();
35                 tsc.SetResult(response);
36                 return tsc.Task;
37             }
38             return base.SendAsync(request, cancellationToken);
39         }
40 
41     }
View Code
原文地址:https://www.cnblogs.com/farmer-y/p/6113331.html