3

我无法通过我的 Windows 商店应用程序下载文件。这是我的下载方法： 

private static async void DownloadImage()
    {
        HttpClient client = new HttpClient();

        HttpResponseMessage message = await client.GetAsync("http://coolvibe.com/wp-content/uploads/2010/05/scifiwallpaper1.jpg");

        StorageFolder myfolder = Windows.Storage.ApplicationData.Current.LocalFolder;
        StorageFile sampleFile = myfolder.CreateFileAsync("image.jpg", CreationCollisionOption.ReplaceExisting).GetResults();// this line throws an exception
        byte[] file = await message.Content.ReadAsByteArrayAsync();

        await FileIO.WriteBytesAsync(sampleFile, file);
        var files = await myfolder.GetFilesAsync();

    }

在标记的行上，我得到了这个异常： 

An exception of type 'System.InvalidOperationException' occurred in ListStalkerWin8.exe but was not handled in user code

WinRT information: A method was called at an unexpected time.

Additional information: A method was called at an unexpected time.

这可能是什么原因造成的？

4

2 回答 2

2

您在尚未完成的 IAsyncOperation 上调用 GetResults，因此不处于可以访问结果的状态（因为它们尚不存在）。

实际上，您根本不需要调用 GetResults，您只需要：

StorageFile sampleFile = await myfolder.CreateFileAsync("image.jpg", CreationCollisionOption.ReplaceExisting);
于 2013-08-14T04:11:04.903 回答
0

改变 

StorageFile sampleFile = myfolder.CreateFileAsync("image.jpg", CreationCollisionOption.ReplaceExisting).GetResults();//

至

StorageFile sampleFile = await myfolder.CreateFileAsync("image.jpg", CreationCollisionOption.ReplaceExisting);

似乎解决了这个问题，虽然我不知道为什么

于 2013-08-08T10:53:09.223 回答