UWP 在文档和图片库中保存文件答案

【问题标题】：UWP save file in Documents and Pictures LibraryUWP 在文档和图片库中保存文件
【发布时间】：2017-01-26 09:15:02
【问题描述】：

我正在尝试制作一个 UWP 应用程序，它可以将保存在自己存储中的文件导出到文档库中。

在 Package.appxmanifest 中，我插入了以下几行：

<uap:Capability Name="picturesLibrary" />
<uap:Capability Name="documentsLibrary" />

获取路径的代码是这样的：

StorageFolder storageFolder = await KnownFolders.GetFolderForUserAsync(null /* current user */, KnownFolderId.DocumentsLibrary);            
string path = storageFolder.Path + "\\" + fileName;

保存文件的代码是这样的：

FileStream writer = new FileStream(filePath, FileMode.Create);

此时，程序启动了这个异常：

Access to the path 'C:\Users\luca9\AppData\Roaming\Microsoft\Windows\Libraries\Documents.library-ms' is denied.

在我的 950XL 上，例外情况类似：

Access to the path 'C:\Data\Users\DefApps\APPDATA\ROAMING\MICROSOFT\WINDOWS\Libraries\Documents.library-ms' is denied.

我已经尝试过 Documents 和 Pictures 库，但我得到了同样的例外。

我该如何解决？

提前谢谢你，

卢卡

【问题讨论】：

你读过这些文章吗？ msdn.microsoft.com/en-us/windows/uwp/files/… .... msdn.microsoft.com/en-us/windows/uwp/files/…
我想我已经错过了他们。非常感谢

标签： c# save uwp access-denied documentsdirectory

【解决方案1】：

不要使用路径获取 FileStream - 应用程序没有权限。由于您已经拥有 StorageFolder，请使用它创建一个 StorageFile，然后使用其中一种方法从中获取流，例如：

var file = await storageFolder.CreateFileAsync("fileName");
using (var stream = await file.OpenAsync(FileAccessMode.ReadWrite))
{
    // do what you want
}

【讨论】：

【解决方案2】：

这个来自 Microsoft 的示例适用于 uwp。

https://docs.microsoft.com/en-us/windows/uwp/files/quickstart-save-a-file-with-a-picker

1.创建和自定义 FileSavePicker

var savePicker = new Windows.Storage.Pickers.FileSavePicker();
savePicker.SuggestedStartLocation =
Windows.Storage.Pickers.PickerLocationId.DocumentsLibrary;
// Dropdown of file types the user can save the file as
savePicker.FileTypeChoices.Add("Plain Text", new List<string>() { ".txt" });
// Default file name if the user does not type one in or select a file to replace
savePicker.SuggestedFileName = "New Document";

2。显示 FileSavePicker 并保存到选择的文件

Windows.Storage.StorageFile file = await savePicker.PickSaveFileAsync();
if (file != null)
{
    // Prevent updates to the remote version of the file until
    // we finish making changes and call CompleteUpdatesAsync.
    Windows.Storage.CachedFileManager.DeferUpdates(file);
    // write to file
    await Windows.Storage.FileIO.WriteTextAsync(file, file.Name);
    // Let Windows know that we're finished changing the file so
    // the other app can update the remote version of the file.
    // Completing updates may require Windows to ask for user input.
    Windows.Storage.Provider.FileUpdateStatus status =
        await Windows.Storage.CachedFileManager.CompleteUpdatesAsync(file);
    if (status == Windows.Storage.Provider.FileUpdateStatus.Complete)
    {
        this.textBlock.Text = "File " + file.Name + " was saved.";
    }
    else
    {
        this.textBlock.Text = "File " + file.Name + " couldn't be saved.";
    }
}
else
{
    this.textBlock.Text = "Operation cancelled.";
}

【讨论】：