Public Function SetNewPrefsForUser() As Double
    Try
        Dim inputChar As Byte
        Dim isoFile As IsolatedStorageFile = IsolatedStorageFile.GetStore(IsolatedStorageScope.User Or _
            IsolatedStorageScope.Assembly Or IsolatedStorageScope.Domain, _
            GetType(System.Security.Policy.Url), GetType(System.Security.Policy.Url))

        ' If this is not a new user, archive the old preferences and 
        ' overwrite them using the new preferences.
        If Not Me.myNewPrefs Then
            If isoFile.GetDirectoryNames("Archive").Length = 0 Then
                isoFile.CreateDirectory("Archive")
            Else

                Dim source As New IsolatedStorageFileStream(Me.userName, FileMode.OpenOrCreate, isoFile)
                Dim canWrite, canRead As Boolean
                ' This is the stream from which data will be read.
                If source.CanRead Then canRead = True Else canRead = False
                Console.WriteLine("Is the source file readable? " & canRead)
                Console.WriteLine("Creating new IsolatedStorageFileStream for Archive.")
                ' Open or create a writable file.
                Dim target As New IsolatedStorageFileStream("Archive\ " & Me.userName, _
                     FileMode.OpenOrCreate, FileAccess.Write, FileShare.Write, isoFile)
                ' This is the stream to which data will be written.
                If target.CanWrite Then canWrite = True Else canWrite = False
                Console.WriteLine("Is the target file writable? " & canWrite)
                target.SetLength(0)  'rewind the target file

                ' Stream the old file to a new file in the Archive directory.
                If source.IsAsync And target.IsAsync Then
                    ' IsolatedStorageFileStreams cannot be asynchronous.  However, you
                    ' can use the asynchronous BeginRead and BeginWrite functions
                    ' with some possible performance penalty.
                    Console.WriteLine("IsolatedStorageFileStreams cannot be asynchronous.")
                Else
                    Console.WriteLine("Writing data to the new file.")
                    While source.Position < source.Length
                        inputChar = CByte(source.ReadByte())
                        target.WriteByte(inputChar)
                    End While

                    ' Determine the size of the IsolatedStorageFileStream
                    ' by checking its Length property.
                    Console.WriteLine(("Total Bytes Read: " & source.Length))
                End If

                ' After you have read and written to the streams, close them.	
                target.Close()
                source.Close()
            End If
        End If
        ' Open or create a writable file with a maximum size of 10K.
        Dim isoStream As New IsolatedStorageFileStream(Me.userName, FileMode.OpenOrCreate, _
            FileAccess.Write, FileShare.Write, 10240, isoFile)
        isoStream.SetLength(0) 'Position to overwrite the old data.

' 导入命名空间
Imports System.IO.IsolatedStorage
        
Public Class Tester
    Public Shared Sub Main

        Dim myIsoStore As IsolatedStorageFile

        Try
            myIsoStore.CreateDirectory("newDir")

            Dim myIsoStroeStream As New IsolatedStorageFileStream("test.txt", IO.FileMode.Create.Create, myIsoStore)
            myIsoStroeStream.Close()
        Catch ex As IsolatedStorageException
            Console.WriteLine(ex.Message)
        End Try
    End Sub
End Class