在ASP.Net Core Web API中返回文件

如果这是ASP.net-Core，则您正在混合使用Web
API版本。让操作返回一个派生，

IActionResult

HttpResponseMessage

[Route("api/[controller]")]public class DownloadController : Controller {    //GET api/download/12345abc    [HttpGet("{id}"]    public async Task<IActionResult> Download(string id) {        Stream stream = await {{__get_stream_based_on_id_here__}}        if(stream == null) return NotFound(); // returns a NotFoundResult with Status404NotFound response.        return File(stream, "application/octet-stream"); // returns a FileStreamResult    }    }