asp的一个下载功能页面，就是把文件直接传给客户端的方式

<%
filepath=request.querystring("filepath")
filenames=Split(filepath,"/")
filename=filenames(1)
Const ForReading=1
Const TristateTrue=-1 'Unicode
Const FILE_TRANSFER_SIZE=16384 '16k
'Use the following line for IIS4/PWS - this is the default for IIS5
Response.Buffer = True

Function TransferFile(path, mimeType, filename)
Dim objFileSystem, objFile, objStream
Dim char
Dim sent
send=0
TransferFile = True

Set objFileSystem = Server.CreateObject("Scripting.FileSystemObject")
Set objFile = objFileSystem.GetFile(Path)
Set objStream = objFile.OpenAsTextStream(ForReading, TristateTrue)

Response.AddHeader "content-type", mineType

Response.ContentType = "application/octet-stream"

response.AddHeader "Content-Disposition","attachment;filename="&filename 
Response.AddHeader "content-length", objFile.Size

Do While Not objStream.AtEndOfStream
char = objStream.Read(1)
Response.BinaryWrite(char)
sent = sent + 1
If (sent MOD FILE_TRANSFER_SIZE) = 0 Then
Response.Flush
If Not Response.IsClientConnected Then
TransferFile = False
Exit Do
End If
End If
Loop

Response.Flush
If Not Response.IsClientConnected Then TransferFile = False

objStream.Close
Set objStream = Nothing
Set objFileSystem = Nothing
End Function

Dim path, mimeType, sucess

path = Server.MapPath(filepath)
mimeType = "application/octet-stream" 
sucess = TransferFile(path, mimeType,filename)

Response.End
%>