public class HttpClientHandler : System.Net.Http.HttpMessageHandler
Inheritance->Object->HttpMessageHandler->HttpclientHandler
Derived System.Net.Http.WebRequestHandler
Examples
C#
static async Task Main()
{
// Create an HttpClientHandler object and set to use default credentials
HttpClientHandler handler = new HttpClientHandler();
handler.UseDefaultCredentials = true;
// Create an HttpClient object
HttpClient client = new HttpClient(handler);
// 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(); Console.WriteLine(responseBody);
}
catch(HttpRequestException e)
{
Console.WriteLine("\nException Caught!");
Console.WriteLine("Message :{0} ",e.Message);
}
// Need to call dispose on the HttpClient and HttpClientHandler objects
// when done using them, so the app doesn't leak resources
handler.Dispose(true);
client.Dispose(true); }
The preceding code example uses an async Task Main() entry point. That feature requires C# 7.1 or later.
Remarks
The HttpClientHandler class and classes derived from it enable developers to configure a variety of options ranging from proxies to authentication.
HttpClientHandler in .NET Core
Starting in .NET Core 2.1, the implementation of the HttpClientHandler class was changed to be based on the cross-platform HTTP protocol stack used by the System.Net.Http.SocketsHttpHandler class. Prior to .NET Core 2.1, the HttpClientHandler class used older HTTP protocol stacks (WinHttpHandler on Windows and CurlHandler, an internal class implemented on top of Linux's native libcurl component, on Linux).
You can configure your app to use the older HTTP protocol stacks in one of the following three ways:
Call the AppContext.SetSwitch method:
C#
AppContext.SetSwitch("System.Net.Http.UseSocketsHttpHandler", false);
Define the System.Net.Http.UseSocketsHttpHandler switch in the .netcore.runtimeconfig.json configuration file:
JSON
"runtimeOptions": { "configProperties": { "System.Net.Http.UseSocketsHttpHandler": false } }
Define an environment variable named DOTNET_SYSTEM_NET_HTTP_USESOCKETSHTTPHANDLER and set it to either false or 0.
Constructors
CONSTRUCTORSHttpClientHandler()
Creates an instance of a HttpClientHandler class.
Properties
PROPERTIESAllowAutoRedirect
Gets or sets a value that indicates whether the handler should follow redirection responses.
AutomaticDecompression
Gets or sets the type of decompression method used by the handler for automatic decompression of the HTTP content response.
CheckCertificateRevocationList
Gets or sets a value that indicates whether the certificate is checked against the certificate authority revocation list.
ClientCertificateOptions
Gets or sets a value that indicates if the certificate is automatically picked from the certificate store or if the caller is allowed to pass in a specific client certificate.
ClientCertificates
Gets the collection of security certificates that are associated requests to the server.
CookieContainer
Gets or sets the cookie container used to store server cookies by the handler.
Credentials
Gets or sets authentication information used by this handler.
DangerousAcceptAnyServerCertificateValidator
Gets a cached delegate that always returns true.
DefaultProxyCredentials
When the default (system) proxy is being used, gets or sets the credentials to submit to the default proxy server for authentication. The default proxy is used only when UseProxy is set to true and Proxy is set to null.
MaxAutomaticRedirections
Gets or sets the maximum number of redirects that the handler follows.
MaxConnectionsPerServer
Gets or sets the maximum number of concurrent connections (per server endpoint) allowed when making requests using an HttpClient object. Note that the limit is per server endpoint, so for example a value of 256 would permit 256 concurrent connections to http://www.adatum.com/ and another 256 to http://www.adventure-works.com/.
MaxRequestContentBufferSize
Gets or sets the maximum request content buffer size used by the handler.
MaxResponseHeadersLength
Gets or sets the maximum length, in kilobytes (1024 bytes), of the response headers. For example, if the value is 64, then 65536 bytes are allowed for the maximum response headers' length.
PreAuthenticate
Gets or sets a value that indicates whether the handler sends an Authorization header with the request.
Properties
Gets a writable dictionary (that is, a map) of custom properties for the HttpClient requests. The dictionary is initialized empty; you can insert and query key-value pairs for your custom handlers and special processing.
Proxy
Gets or sets proxy information used by the handler.
ServerCertificateCustomValidationCallback
Gets or sets a callback method to validate the server certificate.
SslProtocols
Gets or sets the TLS/SSL protocol used by the HttpClient objects managed by the HttpClientHandler object.
SupportsAutomaticDecompression
Gets a value that indicates whether the handler supports automatic response content decompression.
SupportsProxy
Gets a value that indicates whether the handler supports proxy settings.
SupportsRedirectConfiguration
Gets a value that indicates whether the handler supports configuration settings for the AllowAutoRedirect and MaxAutomaticRedirections properties.
UseCookies
Gets or sets a value that indicates whether the handler uses the CookieContainer property to store server cookies and uses these cookies when sending requests.
UseDefaultCredentials
Gets or sets a value that controls whether default credentials are sent with requests by the handler.
UseProxy
Gets or sets a value that indicates whether the handler uses a proxy for requests.
Methods
METHODSDispose()
Releases the unmanaged resources and disposes of the managed resources used by the HttpMessageHandler.
(Inherited from HttpMessageHandler)Dispose(Boolean)
Releases the unmanaged resources used by the HttpClientHandler and optionally disposes of the managed resources.
Equals(Object)
Determines whether the specified object is equal to the current object.
(Inherited from Object)GetHashCode()
Serves as the default hash function.
(Inherited from Object)GetType()
Gets the Type of the current instance.
(Inherited from Object)MemberwiseClone()
Creates a shallow copy of the current Object.
(Inherited from Object)SendAsync(HttpRequestMessage, CancellationToken)
Creates an instance of HttpResponseMessage based on the information provided in the HttpRequestMessage as an operation that will not block.
ToString()
Returns a string that represents the current object.
(Inherited from Object)
