HttpClient 类
定义
重要
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提供一个类，用于从 URI 标识的资源发送 HTTP 请求和接收 HTTP 响应。
public ref class HttpClient : System::Net::Http::HttpMessageInvokerpublic class HttpClient : System.Net.Http.HttpMessageInvokertype HttpClient = class
inherit HttpMessageInvokerPublic Class HttpClient
Inherits HttpMessageInvoker- 继承
示例
// HttpClient is intended to be instantiated once per application, rather than per-use. See Remarks.
static readonly HttpClient client = new HttpClient();
static async Task Main()
{
// Call asynchronous network methods in a try/catch block to handle exceptions.
try
{
using 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);
}
}
open System.Net.Http
// HttpClient is intended to be instantiated once per application, rather than per-use. See Remarks.
let client = new HttpClient()
let main =
task {
// Call asynchronous network methods in a try/catch block to handle exceptions.
try
use! response = client.GetAsync "http://www.contoso.com/"
response.EnsureSuccessStatusCode() |> ignore
let! responseBody = response.Content.ReadAsStringAsync()
// Above three lines can be replaced with new helper method below
// let! responseBody = client.GetStringAsync uri
printfn $"{responseBody}"
with
| :? HttpRequestException as e ->
printfn "\nException Caught!"
printfn $"Message :{e.Message} "
}
main.Wait()
' HttpClient is intended to be instantiated once per application, rather than per-use. See Remarks.
Shared ReadOnly client As HttpClient = New HttpClient()
Private Shared Async Function Main() As Task
' Call asynchronous network methods in a try/catch block to handle exceptions.
Try
Using response As HttpResponseMessage = Await client.GetAsync("http://www.contoso.com/")
response.EnsureSuccessStatusCode()
Dim responseBody As String = Await response.Content.ReadAsStringAsync()
' Above three lines can be replaced with new helper method below
' Dim responseBody As String = Await client.GetStringAsync(uri)
Console.WriteLine(responseBody)
End Using
Catch e As HttpRequestException
Console.WriteLine(Environment.NewLine & "Exception Caught!")
Console.WriteLine("Message :{0} ", e.Message)
End Try
End Function
注解
有关此 API 的详细信息，请参阅 HttpClient 的补充 API 备注。
构造函数
| 名称 | 说明 |
|---|---|
| HttpClient() |
使用HttpClientHandler释放此实例时释放的类的新实例HttpClient初始化该实例。 |
| HttpClient(HttpMessageHandler, Boolean) |
使用提供的处理程序初始化类的新实例 HttpClient ，并指定释放此实例时是否应释放该处理程序。 |
| HttpClient(HttpMessageHandler) |
使用指定的处理程序初始化类的新实例 HttpClient 。 释放此实例时，将释放处理程序。 |
属性
| 名称 | 说明 |
|---|---|
| BaseAddress |
获取或设置发送请求时使用的 Internet 资源的统一资源标识符（URI）的基址。 |
| DefaultProxy |
获取或设置全局 HTTP 代理。 |
| DefaultRequestHeaders |
获取应随每个请求一起发送的标头。 |
| DefaultRequestVersion |
获取或设置此 HttpClient 实例后续请求上使用的默认 HTTP 版本。 |
| DefaultVersionPolicy |
获取或设置隐式创建请求的默认版本策略，例如 GetAsync(String) ，以及 PostAsync(String, HttpContent)。 |
| MaxResponseContentBufferSize |
获取或设置读取响应内容时要缓冲的最大字节数。 |
| Timeout |
获取或设置在请求超时之前要等待的时间跨度。 |
