用Asp隐藏文件路径,实现防盗链

示例代码：
<%
From_url=Cstr(Request.ServerVariables("HTTP_REFERER"))
Serv_url=Cstr(Request.ServerVariables("SERVER_NAME"))
if mid(From_url,8,len(Serv_url)) <> Serv_url then
?response.write "非法链接！" '防止盗链
?response.end
end if
if Request.Cookies("Logined")="" then
?response.redirect "/login.asp" '需要登陆！
end if
Function GetFileName(longname)'/folder1/folder2/file.asp=>file.asp
?while instr(longname,"/")
longname=right(longname,len(longname)-1)
?wend
?GetFileName=longname
End Function

Dim Stream
Dim Contents
Dim FileName
Dim TrueFileName
Dim FileExt
Const adTypeBinary=1
FileName=Request.QueryString("FileName")
if FileName="" Then
Response.Write "无效/webpage/asp/041101/24.htm！"
Response.End
End if

FileExt=Mid(FileName, InStrRev(FileName, ".") + 1)
Select Case UCase(FileExt)
Case "ASP", "ASA", "ASPX", "ASAX", "MDB"
Response.Write "非法操作！"
Response.End
End Select

Response.Clear

if lcase(right(FileName,3))="gif" or lcase(right(FileName,3))="jpg" or lcase(right(FileName,3))="png" then
?Response.ContentType="image/*" '对图像文件不出现下载对话框
else
?Response.ContentType="application/ms-download"
end if

Response.AddHeader "content-disposition", "attachment; 200497141230.htm=" & GetFileName(Request.QueryString("FileName"))
Set Stream=server.CreateObject("ADODB.Stream")
Stream.Type=adTypeBinary
Stream.Open
if lcase(right(FileName,3))="pdf" then '设置pdf类型文件目录
?TrueFileName="/the_pdf_file_s/"&FileName
end if
if lcase(right(FileName,3))="doc" then '设置DOC类型文件目录
?TrueFileName="/my_D_O_C_file/"&FileName
end if
if lcase(right(FileName,3))="gif" or lcase(right(FileName,3))="jpg" or lcase(right(FileName,3))="png" then
?TrueFileName="/all_images_/"&FileName '设置图像文件目录
end if
Stream.LoadFromFile Server.MapPath(TrueFileName)
While Not Stream.EOS
?Response.BinaryWrite Stream.Read(1024 * 64)
Wend
Stream.Close
Set Stream=Nothing
Response.Flush
Response.End
%>