上传到azure存储区返回一个空文件

Question

我的上传工作方式如下：

1. 我有两种方法，一种调整图像大小，另一种上传完整图像尺寸。
2. 我的上传方法工作正常，因为我可以在我的blob中找到问题，当我尝试下载完整的图像时它返回一个0号文件，但调整后的图像效果很好。

以下是一些背景信息：

public async Task<UserProfile> PostProfilePictureAsync(int userId, IFormFile file)
    {
        var stream = file.OpenReadStream();
        var name = file.FileName;
        var thumbName = "resized_"+file.FileName;

        var resizedStream = ResizeImage(stream);
        var uploadedFileUrl = await UploadFileAsBlob(stream, name);
        var uploadedResizedUrl = await UploadFileAsBlob(resizedStream, thumbName);

        var entity = await _context.UserProfile.FirstOrDefaultAsync(r => r.userId == userId);
        entity.PictureUrl = uploadedFileUrl;
        entity.ThumbnailUrl = uploadedResizedUrl;
        _context.Entry(entity).State = EntityState.Modified;
        _context.SaveChanges();

        return Mapper.Map<UserProfile>(entity);

    }

private Stream ResizeImage(Stream stream) {
        MemoryStream result = new MemoryStream();
        // Create a new image 
        var image = Image.FromStream(stream);
        // Set the image size for the final size values
        var resizedImage = new Bitmap(80, 80);
        // Draw the image inside a new graphic container
        Graphics g = Graphics.FromImage(resizedImage);
        g.DrawImage(image,0,0,80,80);
        // Save that new image and return the stream
        result.Position = 0;
        resizedImage.Save(result,System.Drawing.Imaging.ImageFormat.Jpeg);
        result.Position = 0;
        return result;
    }

private async Task<string> UploadFileAsBlob(Stream stream, string filename)
    {
        CloudStorageAccount storageAccount = new CloudStorageAccount(new Microsoft.WindowsAzure.Storage.Auth.StorageCredentials("my_credentials", "my_key"), true);
        CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();
        CloudBlobContainer container = blobClient.GetContainerReference("my_reference");
        CloudBlockBlob blockBlob = container.GetBlockBlobReference(filename);
        await blockBlob.UploadFromStreamAsync(stream);
        stream.Dispose();
        return blockBlob?.Uri.ToString();
    }

任何人都知道我犯了哪个错误，我觉得我可能需要将uploadToBlob分开，因为它会导致流错误。任何帮助，将不胜感激。以下是一些供参考的图片：

Answer 1

正如Camilo Terevinto所说，你需要在调用ResizeImage（）之后设置stream.Position = 0;。那么它应该适合你。

var resizedStream = ResizeImage(stream);
stream.Position = 0 //add this code.
var uploadedFileUrl = await UploadFileAsBlob(stream, name);