利用.net core实现反向代理中间件的方法

public class ReverseProxy
  {
    static HttpClient _http = new HttpClient();

    public static async Task Invoke(HttpContext context)
    {
      var url = context.Request.Path.ToUriComponent();
      var uri = new Uri("http://localhost:8080/api" + url);

      var request  = CopyRequest(context, uri);
      var remoteRsp = await _http.SendAsync(request);
      var rsp    = context.Response;

      foreach (var header in remoteRsp.Headers)
      {
        rsp.Headers.Add(header.Key, header.Value.ToArray());
      }

      rsp.ContentType  = remoteRsp.Content.Headers.ContentType?.ToString();
      rsp.ContentLength = remoteRsp.Content.Headers.ContentLength;

      await remoteRsp.Content.CopyToAsync(rsp.Body);
    }


    static HttpRequestMessage CopyRequest(HttpContext context, Uri targetUri)
    {
      var req = context.Request;
      var requestMessage = new HttpRequestMessage()
      {
        Method   = new HttpMethod(req.Method),
        Content  = new StreamContent(req.Body),
        RequestUri = targetUri,
      };

      foreach (var header in req.Headers)
      {
        requestMessage.Content?.Headers.TryAddWithoutValidation(header.Key, header.Value.ToArray());
      }

      requestMessage.Headers.Host = targetUri.Host;

      return requestMessage;
    }
  }

  app.Run(Middleware.ReverseProxy.Invoke);