In C#, the HttpClient
class is used to send HTTP requests and receive HTTP responses. By default, HttpClient
uses the system proxy settings that are configured in the operating system, unless you override these settings.
To ensure that HttpClient
uses the system proxy settings, you can set up an HttpClientHandler
and pass it to the HttpClient
constructor. Here's a step-by-step guide:
- Create an instance of
HttpClientHandler
. - Set the
UseProxy
property totrue
to enable proxy use. - Optionally, set the
UseDefaultCredentials
property totrue
if your proxy requires authentication and you want to use the default network credentials. - Create an instance of
HttpClient
with the configuredHttpClientHandler
.
Here is an example in C#:
using System;
using System.Net.Http;
using System.Threading.Tasks;
class Program
{
static async Task Main(string[] args)
{
// Create an instance of HttpClientHandler
var httpClientHandler = new HttpClientHandler
{
// Use system proxy settings
UseProxy = true,
// Use default credentials for proxy authentication if required
UseDefaultCredentials = true
};
// Create an instance of HttpClient with the handler
using (var httpClient = new HttpClient(httpClientHandler))
{
try
{
// Send a GET request
string response = await httpClient.GetStringAsync("http://example.com");
Console.WriteLine(response);
}
catch (HttpRequestException e)
{
Console.WriteLine("Error while making request: " + e.Message);
}
}
}
}
In this example, the HttpClientHandler
is configured to use the system's proxy settings. The UseProxy
property is by default set to true
, but it's explicitly set in this example for clarity. The UseDefaultCredentials
is also set to true
to ensure that if the proxy server requires authentication, the system's default credentials are used. If you don't require default credentials for proxy authentication, you can omit that line or set it to false
.
When the HttpClient
instance is created using this handler, it will automatically adhere to the proxy settings as configured on the user's system.
Remember that the HttpClient
instance should be instantiated once and reused throughout the life of an application, rather than per request. This is to reduce the number of sockets used and to improve performance.
Also, note that some applications might run in environments where the default proxy settings are not appropriate or need to be bypassed for specific requests. In such cases, you can set the proxy manually in the HttpClientHandler
:
httpClientHandler.Proxy = new WebProxy("http://yourproxyaddress:port", true);
Replace "http://yourproxyaddress:port"
with your proxy server's URI and port number. The second parameter to WebProxy
constructor is bypassOnLocal
, which you can set to true
if you want to bypass the proxy for local addresses.
Always make sure to handle exceptions that may occur due to network errors or invalid proxy settings by using appropriate try-catch blocks around your HTTP calls.