［原］Asp.net中以对话框形式下载文件（VB.net）

    Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        '在此处放置初始化页的用户代码
        Dim imgUrl As String = Me.Request.QueryString("url") '//取出文件的物理路径。
        Me.DownloadFile(imgUrl)
    End Sub
  
  Private Function DownloadFile(ByVal filename As String)
        Dim saveFileName As String
        Dim startIndex As Int32 = filename.LastIndexOf("\") + 1
        saveFileName = filename.Substring(startIndex)
        Dim fi As System.IO.FileInfo = New System.IO.FileInfo(filename)
        Dim fileExtName As String = fi.Extension
        Dim DEFAULT_CONTENT_TYPE As String = "application/unknown"
        Dim regKey, fileExtKey As Microsoft.Win32.RegistryKey
        Dim fileContentType As String
        Try
            regKey = Microsoft.Win32.Registry.ClassesRoot
            fileExtKey = regKey.OpenSubKey(fileExtName)
            fileContentType = fileExtKey.GetValue("Content Type", DEFAULT_CONTENT_TYPE)

        Catch ex As Exception
            fileContentType = DEFAULT_CONTENT_TYPE
        End Try
        Me.Response.Clear()
        Response.Charset = "utf-8"
        Me.Response.Buffer = True
        Me.EnableViewState = False
        Me.Response.ContentEncoding = System.Text.Encoding.UTF8
        Me.Response.AppendHeader("Content-Disposition", "attachment;filename=" & saveFileName)
        Me.Response.ContentType = fileContentType
        Me.Response.WriteFile(filename)
        Me.Response.Flush()
        Me.Response.End()
    End Function

我的这个程序能够下载Jpg图片等文件，但在保存对话框中的文件名，如果是汉字就不能正常显示（显示乱码），字母和数字都能正常显示，希望各位能帮忙解决一下。先谢了