我们用FSO来读取文件之前,判断querystring的值是否和session的值想符合,不相符合就不读取文件.如果相符合就读出css文件发送到客户端.然后将session清空.

代码如下:

显示文件showfile.asp

<%
if session("css")="" then
       session("css")=session.sessionid
end if
if request("sss")<>session("css") then
       response.write "非法链接!"
       response.end
end if
session("css")="" '关键是这里,将CSS文件显示后,立即将session清空,也可以采用session.abandon方法,但是那将把所有的session都清空了
FileName=server.MapPath("css.css")
Set fso=Server.CreateObject("Scripting.FileSystemObject")
if fso.fileexists(FileName)=false then
       FileName=server.MapPath("images/fileerror.gif")
       flsize=16384
       'flname=FileName
else
        Set fl=fso.getfile(FileName)
        flsize=fl.size
        'flname=fl.name
        Set fl=Nothing
end if
Set fso=Nothing
'response.write filename
'response.end
Response.Clear
dim UpFileExt,CType
UpFileExt=lcase(right(FileName,4))
flname="webstudio" & UpFileExt
Select Case UpFileExt
Case ".asf",".avi",".mpg","mpeg",".mov",".3gp",".wmv"
        CType = "video/*"
Case ".wma"
       CType="audio/x-ms-wma"
Case ".wav",".mp3"
        CType = "audio/*"
Case ".bmp"
       CType="application/x-bmp"
Case ".png"
       CType="application/x-png"
Case ".gif",".jpg","jpeg"
       CType = "image/*"
Case ".doc"
       CType = "application/msword"
Case ".exe"
       CType = "application/x-msdownload "
Case ".pdf"
       CType = "application/pdf"
'Case "rmvb"
       'CType="application/vnd.rn-realmedia-vbr"
Case ".zip"
       CType = "application/zip"
Case ".xls"
       CType = "application/vnd.ms-excel"
Case ".ppt"
       CType = "application/vnd.ms-powerpoint"
Case ".mdb"
       CType = "application/x-msaccess"
Case ".rtf"
       CType = "application/rtf"
Case ".htm", "html"
       CType = "text/html"
Case ".txt"
       CType = "text/plain"
Case Else
       CType = "application/octet-stream"
End Select
Response.AddHeader "content-disposition","attachment; filename=" & flname
Response.AddHeader "Content-Length",flsize
Response.Charset = "UTF-8"
Response.ContentType=CType
Set Stream = server.CreateObject("ADODB.Stream")
Stream.Type = 1'adTypeBinary
Stream.Open
Stream.LoadFromFile FileName
While Not Stream.EOS
Response.BinaryWrite Stream.Read()
Wend
Stream.Close
Set Stream = Nothing
Response.Flush
Response.End
%>
前台调用:
<link rel="stylesheet" type="text/css" href="showfile.asp?sss=<%=session.SessionID%>" />

前台将参数sss传递给showfile.asp,showfile.asp通过判断sss是否与session("css")相一致来决定是否将css文件传递给客户端.
我测试了一下,OK