c# - 从 WP8 将照片上传到 Azure 存储

Question

我无法使用 CloudBlockBlob 将照片上传到 Azure 存储

    //module level variables
    CameraCaptureTask cameraCaptureTask;
    Stream _media;

    // Constructor
    public MainPage()
    {
        InitializeComponent();

        cameraCaptureTask = new CameraCaptureTask();
        cameraCaptureTask.Completed += new EventHandler<PhotoResult>(cameraCaptureTask_Completed);
    }

    private void Button_Click_1(object sender, RoutedEventArgs e)
    {
        cameraCaptureTask.Show();
    }

    private async void cameraCaptureTask_Completed(object sender, PhotoResult e)
    {
        _media = e.ChosenPhoto;

        ShowPhotoOnScreen();
        var todoItem = CreateToDo(e);
        await UploadFileToAzureStorage(todoItem);
    }

    //Works good till here. It will go off and never come back.
    private async Task UploadFileToAzureStorage(TodoItem todoItem)
    {

            Stream _media ;

            // Upload the new image as a BLOB from the stream.
            CloudBlockBlob blobFromSASCredential = container.GetBlockBlobReference(todoItem.ResourceName);
            _photoCache.Position = 0;
            await blobFromSASCredential.UploadFromStreamAsync(_media );
    }

这将异步启动并且永远不会返回。我有一种感觉，我在流中做错了什么。

我的问题：

1. 我应该如何处理流？
2. 我在 UploadFromStreamAsync 上没有看到已完成的事件，是否有一种巧妙的方法来捕获 OnCompleted 或我应该使用的其他方法？

在 Azure 存储教程中可以找到类似的代码，并且适用于 Win8： http: //www.windowsazure.com/en-us/develop/mobile/tutorials/upload-images-to-storage-dotnet/

            StorageFile _media = null;

            // Get the new image as a stream.
            using (var fileStream = await _media.OpenStreamForReadAsync())
            {
               ...

                // Upload the new image as a BLOB from the stream.
                CloudBlockBlob blobFromSASCredential = container.GetBlockBlobReference(todoItem.ResourceName);
                await blobFromSASCredential.UploadFromStreamAsync(fileStream.AsInputStream());
            }

Win8 与 WP8 示例的主要区别是

1. 照片是在 WP8 中捕获的 StorageFile (Win8) 和 Stream。
2. AsInputStream 在 WP8 中似乎无效

如果您需要更多信息，请告诉我。谢谢。