在ASP.NET Core 2.0中，你可以使用Microsoft.AspNetCore.Mvc模版控制器来接收POST参数并将其转换为流。以下是一个示例：

```csharp using System.Collections.Generic; using System.IO; using System.Net.Http; using Microsoft.AspNetCore.Mvc;

namespace YourProjectName.Controllers { [ApiController] [Route("[controller]")] public class MyController : ControllerBase { private readonly HttpClient _httpClient; private readonly string _streamContent;

    public MyController(HttpClient httpClient, string streamContent)
    {
        _httpClient = httpClient;
        _streamContent = streamContent;
    }

    [HttpPost]
    public IActionResult Post([FromBody] Stream content)
    {
        var byteStream = content.ToArray();
        var response = new HttpResponseMessage();
        response.Content = new StringContent(new byte[byteStream.Length], Encoding.UTF8, "application/octet-stream");
        response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
        response.Content.Headers.ContentLength = byteStream.Length;
        return Ok(response);
    }
}

} ```

在这个示例中，我们创建了一个名为MyController的控制器，它接受一个名为"content"的POST请求。然后，我们使用ConvertStream方法将流转换为字节数组，然后创建一个新的HttpResponse对象。最后，我们将这个HttpResponse对象设置为响应体，并将其设置为"application/octet-stream"的类型和大小。