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HttpClient Class

HttpClient Class

.NET Framework 4.6 and 4.5

Provides a base class for sending HTTP requests and receiving HTTP responses from a resource identified by a URI.

Namespace:  System.Net.Http
Assembly:  System.Net.Http (in System.Net.Http.dll)

public class HttpClient : HttpMessageInvoker

The HttpClient type exposes the following members.

  NameDescription
Public methodHttpClient()Initializes a new instance of the HttpClient class.
Public methodHttpClient(HttpMessageHandler)Initializes a new instance of the HttpClient class with a specific handler.
Public methodHttpClient(HttpMessageHandler, Boolean)Initializes a new instance of the HttpClient class with a specific handler.
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  NameDescription
Public propertyBaseAddressGets or sets the base address of Uniform Resource Identifier (URI) of the Internet resource used when sending requests.
Public propertyDefaultRequestHeadersGets the headers which should be sent with each request.
Public propertyMaxResponseContentBufferSizeGets or sets the maximum number of bytes to buffer when reading the response content.
Public propertyTimeoutGets or sets the timespan to wait before the request times out.
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  NameDescription
Public methodCancelPendingRequestsCancel all pending requests on this instance.
Public methodDeleteAsync(String)Send a DELETE request to the specified Uri as an asynchronous operation.
Public methodDeleteAsync(Uri)Send a DELETE request to the specified Uri as an asynchronous operation.
Public methodDeleteAsync(String, CancellationToken)Send a DELETE request to the specified Uri with a cancellation token as an asynchronous operation.
Public methodDeleteAsync(Uri, CancellationToken)Send a DELETE request to the specified Uri with a cancellation token as an asynchronous operation.
Public methodDispose()Releases the unmanaged resources and disposes of the managed resources used by the HttpMessageInvoker. (Inherited from HttpMessageInvoker.)
Protected methodDispose(Boolean)Releases the unmanaged resources used by the HttpClient and optionally disposes of the managed resources. (Overrides HttpMessageInvoker.Dispose(Boolean).)
Public methodEquals(Object)Determines whether the specified object is equal to the current object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetAsync(String)Send a GET request to the specified Uri as an asynchronous operation.
Public methodGetAsync(Uri)Send a GET request to the specified Uri as an asynchronous operation.
Public methodGetAsync(String, HttpCompletionOption)Send a GET request to the specified Uri with an HTTP completion option as an asynchronous operation.
Public methodGetAsync(String, CancellationToken)Send a GET request to the specified Uri with a cancellation token as an asynchronous operation.
Public methodGetAsync(Uri, HttpCompletionOption)Send a GET request to the specified Uri with an HTTP completion option as an asynchronous operation.
Public methodGetAsync(Uri, CancellationToken)Send a GET request to the specified Uri with a cancellation token as an asynchronous operation.
Public methodGetAsync(String, HttpCompletionOption, CancellationToken)Send a GET request to the specified Uri with an HTTP completion option and a cancellation token as an asynchronous operation.
Public methodGetAsync(Uri, HttpCompletionOption, CancellationToken)Send a GET request to the specified Uri with an HTTP completion option and a cancellation token as an asynchronous operation.
Public methodGetByteArrayAsync(String)Send a GET request to the specified Uri and return the response body as a byte array in an asynchronous operation.
Public methodGetByteArrayAsync(Uri)Send a GET request to the specified Uri and return the response body as a byte array in an asynchronous operation.
Public methodGetHashCodeServes as the default hash function. (Inherited from Object.)
Public methodGetStreamAsync(String)Send a GET request to the specified Uri and return the response body as a stream in an asynchronous operation.
Public methodGetStreamAsync(Uri)Send a GET request to the specified Uri and return the response body as a stream in an asynchronous operation.
Public methodGetStringAsync(String)Send a GET request to the specified Uri and return the response body as a string in an asynchronous operation.
Public methodGetStringAsync(Uri)Send a GET request to the specified Uri and return the response body as a string in an asynchronous operation.
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodPostAsync(String, HttpContent)Send a POST request to the specified Uri as an asynchronous operation.
Public methodPostAsync(Uri, HttpContent)Send a POST request to the specified Uri as an asynchronous operation.
Public methodPostAsync(String, HttpContent, CancellationToken)Send a POST request with a cancellation token as an asynchronous operation.
Public methodPostAsync(Uri, HttpContent, CancellationToken)Send a POST request with a cancellation token as an asynchronous operation.
Public methodPutAsync(String, HttpContent)Send a PUT request to the specified Uri as an asynchronous operation.
Public methodPutAsync(Uri, HttpContent)Send a PUT request to the specified Uri as an asynchronous operation.
Public methodPutAsync(String, HttpContent, CancellationToken)Send a PUT request with a cancellation token as an asynchronous operation.
Public methodPutAsync(Uri, HttpContent, CancellationToken)Send a PUT request with a cancellation token as an asynchronous operation.
Public methodSendAsync(HttpRequestMessage)Send an HTTP request as an asynchronous operation.
Public methodSendAsync(HttpRequestMessage, HttpCompletionOption)Send an HTTP request as an asynchronous operation.
Public methodSendAsync(HttpRequestMessage, CancellationToken)Send an HTTP request as an asynchronous operation. (Overrides HttpMessageInvoker.SendAsync(HttpRequestMessage, CancellationToken).)
Public methodSendAsync(HttpRequestMessage, HttpCompletionOption, CancellationToken)Send an HTTP request as an asynchronous operation.
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
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The HttpClient class instance acts as a session to send HTTP requests. An HttpClient instance is a collection of settings applied to all requests executed by that instance. In addition, every HttpClient instance uses its own connection pool, isolating its requests from requests executed by other HttpClient instances.

The HttpClient also acts as a base class for more specific HTTP clients. An example would be a FacebookHttpClient providing additional methods specific to a Facebook web service (a GetFriends method, for instance).

By default, HttpWebRequest will be used to send requests to the server. This behavior can be modified by specifying a different channel in one of the constructor overloads taking a HttpMessageHandler instance as parameter. If features like authentication or caching are required, WebRequestHandler can be used to configure settings and the instance can be passed to the constructor. The returned handler can be passed to one of the constructor overloads taking a HttpMessageHandler parameter.

If an app using HttpClient and related classes in the System.Net.Http namespace intends to download large amounts of data (50 megabytes or more), then the app should stream those downloads and not use the default buffering. If the default buffering is used the client memory usage will get very large, potentially resulting in substantially reduced performance.

The following methods are thread safe:

  1. CancelPendingRequests

  2. DeleteAsync

  3. GetAsync

  4. GetByteArrayAsync

  5. GetStreamAsync

  6. GetStringAsync

  7. PostAsync

  8. PutAsync

  9. SendAsync

   static async void Main()
	 {

      // Create a New HttpClient object.
      HttpClient client = new HttpClient();

      // Call asynchronous network methods in a try/catch block to handle exceptions 
      try	
      {
         HttpResponseMessage response = await client.GetAsync("http://www.contoso.com/");
         response.EnsureSuccessStatusCode();
         string responseBody = await response.Content.ReadAsStringAsync();
         // Above three lines can be replaced with new helper method below 
         // string responseBody = await client.GetStringAsync(uri);

         Console.WriteLine(responseBody);
      }  
      catch(HttpRequestException e)
      {
         Console.WriteLine("\nException Caught!");	
         Console.WriteLine("Message :{0} ",e.Message);
      }

      // Need to call dispose on the HttpClient object 
      // when done using it, so the app doesn't leak resources
      client.Dispose(true);
   }

.NET Framework

Supported in: 4.6, 4.5

.NET for Windows Phone apps

Supported in: Windows Phone 8.1

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
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