文件下载？

Question

Dim fName1 As String = e.Item.Cells(1).Text.Trim  '文件名
        Dim fName As String
        '****************文件下载***********************************************
        Try
            fName = viewstate("curDirectory") + fName1   ‘全路径文件名
            Dim fInfo As System.IO.FileInfo = New FileInfo(fName)
            Response.Clear()
            Response.ClearContent()
            Response.ClearHeaders()
            Response.Buffer = True
            Response.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(fName1, System.Text.Encoding.UTF8))
            Response.AddHeader("Content-Length", fInfo.Length.ToString())
            Response.ContentType = "application/octet-stream"
            Dim MyFileStream As FileStream = New FileStream(fName, System.IO.FileMode.Open, System.IO.FileAccess.Read, System.IO.FileShare.Read)
            Dim FileSize As Long = MyFileStream.Length
            Dim Buffer(CInt(FileSize)) As Byte
            MyFileStream.Read(Buffer, 0, Int32.Parse(FileSize))
            MyFileStream.Close()
            Response.BinaryWrite(Buffer)
         Catch ex As Exception
            Page.RegisterStartupScript("look", "<script language='javascript'>window.alert('文件不存在！' )</script>")
            Exit Sub
        Finally
            Response.End()
        End Try

Answer 1

<%@ Page Language="VB" Debug="true"%>
<%@ Import NameSpace="System.IO" %>
<%@ Import NameSpace="System.Net" %>
<script runat="server">
Sub Button1_Click(s As Object,e As EventArgs)
    DownloadFile("c:\rt.gif",true)
End SubSub DownloadFile(ByVal fname As String, ByVal forceDownload As Boolean)
  Dim path As Path
  Dim fullpath = path.GetFullPath(fname)
  Dim name = path.GetFileName(fullpath)
  Dim ext = path.GetExtension(fullpath)
  Dim type As String = ""
  If Not IsDBNull(ext) Then
      ext = LCase(ext)
  End If
  Select Case ext
      Case ".htm", ".html"
          type = "text/HTML"
      Case ".txt"
          type = "text/plain"
      Case ".doc", ".rtf"
          type = "Application/msword"
      Case ".csv", ".xls"
          type = "Application/x-msexcel"
      Case Else
          type = "text/plain"
  End Select
  If (forceDownload) Then
      Response.AppendHeader("content-disposition", _
      "attachment; filename=" + name)
  End If
  If type <> "" Then
      Response.ContentType = type
  End If
  Response.WriteFile(fullpath)
  Response.End()
End Sub
</script>
<form runat="server">
<asp:Button id="button1" onclick="Button1_Click" runat="server" Text="DownLoadFile"/>
</form>