Question

如何将我的文件从本地存储复制到SD卡或WP8.1中的已知文件夹以进行备份？

我正在使用文件夹选择器来选择保存位置。

我的代码是：

Private Async Sub ButtonBackup_Click(sender As Object, e As RoutedEventArgs)
    Dim FolderPicker As New FolderPicker()
    FolderPicker.SuggestedStartLocation = PickerLocationId.DocumentsLibrary

    FolderPicker.ViewMode = PickerViewMode.List
    FolderPicker.PickFolderAndContinue()

End Sub

Public Async Sub ContinueFolderPicker(ByVal args As FolderPickerContinuationEventArgs) Implements IFolderPickerContinuable.ContinueFolderPicker
    Dim folder As StorageFolder = args.Folder
    If folder IsNot Nothing Then
        ' Application now has read/write access to all contents in the picked folder (including other sub-folder contents)
        StorageApplicationPermissions.FutureAccessList.AddOrReplace("PickedFolderToken", folder)
        'OutputTextBlock.Text = "Picked folder: " & folder.Name
    Else
        'OutputTextBlock.Text = "Operation cancelled."
    End If
    Dim file As StorageFile = Await Windows.Storage.ApplicationData.Current.LocalFolder.GetFileAsync("ContactsManager.sqlite")
    CopyFileToFolder(file, folder)

End Sub

Public Async Sub CopyFileToFolder(ByVal filetoCopy As StorageFile, ByVal folder As StorageFolder)
    Await filetoCopy.CopyAsync(folder)
End Sub

但下面的行没有开始：

Public Async Sub ContinueFolderPicker(ByVal args As FolderPickerContinuationEventArgs) Implements IFolderPickerContinuable.ContinueFolderPicker

Answer 1

最后我解决了我的问题，下面的代码是正确的。

Private Async Sub ButtonBackup_Click(sender As Object, e As RoutedEventArgs)
    Dim SqliteStorageFile As StorageFile = Await Windows.Storage.ApplicationData.Current.LocalFolder.GetFileAsync("ContactsManager.sqlite")

    Dim buffer() As Byte
    Dim stream As Stream = Await SqliteStorageFile.OpenStreamForReadAsync()
    buffer = New Byte(stream.Length - 1) {}
    Await stream.ReadAsync(buffer, 0, CInt(stream.Length))

    Dim savePicker = New FileSavePicker()
    savePicker.FileTypeChoices.Add("Backup File", New List(Of String)() From {".backup"})
    savePicker.SuggestedFileName = SqliteStorageFile.Name

    Dim file = Await savePicker.PickSaveFileAsync()
    If file IsNot Nothing Then
        CachedFileManager.DeferUpdates(file)
        Await FileIO.WriteBytesAsync(file, buffer)
        CachedFileManager.CompleteUpdatesAsync(file)
    End If
End Sub

在WP8.1中将Sqlite文件从本地存储复制到SD卡

1 个答案: