如何将 HTTP 响应转发给客户端

Question

我有一个客户端 (Xamarin) 和两个 Web API 服务器，A 和 B。客户端向 A 发出请求，A 使用请求参数向 B 发出另一个请求。我如何 return A 从 B 接收到客户端的响应，这样 B 对 C 的使用对客户端是透明的。

例如，如果我使用 HttpClient 从 A 向 B 发出请求，我如何在控制器的操作中将 HttpResponseMessage 转发给客户端？

Answer 1

这是服务器端：

WebForm1.aspx.cs

protected void Page_Load(object sender, EventArgs e)
    {
        HttpClient client = new HttpClient();
        client.Timeout = TimeSpan.FromSeconds(10);

        client.GetAsync("http://localhost:14388/WebForm2.aspx").ContinueWith(
             getTask =>
             {
                 if (getTask.IsCanceled)
                 {
                     Console.WriteLine("Request was canceled");
                 }
                 else if (getTask.IsFaulted)
                 {
                     Console.WriteLine("Request failed: {0}", getTask.Exception);
                 }
                 else
                 {
                     HttpResponseMessage response = getTask.Result;

                     string _message = response.Content.ReadAsStringAsync()
                                           .Result
                                           .Replace("\", "")
                                           .Trim(new char[1] { '"' });
                 }
             });
    }

WebForm2.aspx:

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm2.aspx.cs" Inherits="Volkan.WebForm2" %>

WebForm2.aspx.cs:

protected void Page_Load(object sender, EventArgs e)
    {
        Response.Write("ahada cevabım");
    }

这是客户端：

Answer 2

查看 aspnet/AspLabs 存储库以获得透明 HTTP 代理的良好示例。该代理是处理客户端对 A 的请求并向 B 发出自己的请求的中间件。

为了提供完整的答案，这是其源代码的一部分，它实际上转发了一个HttpResponseMessage：

using (var responseMessage = await _httpClient.SendAsync(
    requestMessage, HttpCompletionOption.ResponseHeadersRead, context.RequestAborted))
{
    context.Response.StatusCode = (int)responseMessage.StatusCode;
    foreach (var header in responseMessage.Headers)
    {
        context.Response.Headers[header.Key] = header.Value.ToArray();
    }

    foreach (var header in responseMessage.Content.Headers)
    {
        context.Response.Headers[header.Key] = header.Value.ToArray();
    }

    // SendAsync removes chunking from the response. This removes the header so it doesn't expect a chunked response.
    context.Response.Headers.Remove("transfer-encoding");
    await responseMessage.Content.CopyToAsync(context.Response.Body);
}

full code 将收到的 HttpResponseMessage 复制到存储库中的 HttpContext.Response。

Answer 3

我采纳了 IIya 的回答并将其改编为 asp.net MVC 5

 public async Task GetFile(CancellationToken cancellationToken)
    {
        var context = HttpContext;
        var _httpClient = StaticHttpClient.Instance;
        var requestMessage = new HttpRequestMessage()
        {
            RequestUri = new Uri("https://localhost:44305/api/files/123"),
        };
        using (var responseMessage = await _httpClient.SendAsync(
requestMessage, HttpCompletionOption.ResponseHeadersRead, cancellationToken))
        {
            Response.StatusCode = (int)responseMessage.StatusCode;
            foreach (var header in responseMessage.Headers)
            {
                Response.Headers[header.Key] = header.Value.First();
            }
            foreach (var header in responseMessage.Content.Headers)
            {
                Response.Headers[header.Key] = header.Value.First();
            }
            Response.Headers.Remove("transfer-encoding");
            //Response.BinaryWrite(await responseMessage.Content.ReadAsByteArrayAsync());
            await responseMessage.Content.CopyToAsync(Response.OutputStream);
            Response.Flush();
            Response.Close();
            context.ApplicationInstance.CompleteRequest();
        }
    }

如何将 HTTP 响应转发给客户端

How to forward HTTP response to client

c#

asp.net-core

asp.net-core-webapi