c# - ASP.Net Core Web API 中的返回文件

Question

问题

我想在我的 ASP.Net Web API Controller 中返回一个文件，但我所有的方法都将 HttpResponseMessage 作为 JSON 返回。

到目前为止的代码

public async Task<HttpResponseMessage> DownloadAsync(string id)
{
    var response = new HttpResponseMessage(HttpStatusCode.OK);
    response.Content = new StreamContent({{__insert_stream_here__}});
    response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
    return response;
}

当我在浏览器中调用此端点时，Web API 返回 HttpResponseMessage 作为 JSON，并将 HTTP 内容 header 设置为 application/json。

Answer 1

如果这是 ASP.net-Core，那么您正在混合 Web API 版本。让操作返回派生的 IActionResult，因为在您当前的代码中，框架将 HttpResponseMessage 视为模型。

[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
    }    
}

注意:

The framework will dispose of the stream used in this case when the response is completed. If a using statement is used, the stream will be disposed before the response has been sent and result in an exception or corrupt response.