无法从ASP.NET MVC中的操作返回图像流

Question

我有以下行动：

StaticImage

我有一个检索//E is StaticImage in this case //The returned entity is not disposed, it leaves that responsability to the controller //However, the response IS disposed, that's why I need to copy the stream public async Task<E> SelectAsync(params object[] keys) { using(GetObjectResponse response = await MakeGetObjectRequestAsync(keys.First().ToString())) { if(response == null) return default(E); E entity = CreateEntity(); entity.Key = response.Key; Stream entityStream = new MemoryStream(Convert.ToInt32(response.ResponseStream.Length)); await response.ResponseStream.CopyToAsync(entityStream); entity.Stream = entityStream; return entity; } } 的通用持久性策略（使用Amazon S3），如下所示：

response.ResponseStream

Length包含图片的内容：

它正好被复制到新流（参见0）：

但是，我的控制器会返回10 +++ DO I = 1 TO SYSTSIN.0 Error running MYREXX, line 10: Bad arithmetic conversion 个字节：

Answer 1

如果查看第二张图片，则流的位置为197397。我的假设是当你将它传递给FileStreamResult的构造函数时，它不会复制它，因为位置在流的末尾。在将其传递给FileStreamResult的构造函数之前，请将位置设置回0：

StaticImage image = await _images.UseRepositoryAsync(repo => repo.ReadAsync(path));     
image.Stream.Position = 0;
return image != null ? new FileStreamResult(image.Stream, "image/jpeg") : (ActionResult)HttpNotFound();