ASP实现301重定向跳转代码

<%
'--301重定向
Dim Server_Name,Path_infostr,Query_Stringstr
Path_infostr=lcase(request.ServerVariables("PATH_INFO"))
Server_Name=lcase(request.ServerVariables("Server_Name"))
Query_Stringstr=request.ServerVariables("Query_String")
If  Query_Stringstr<>"" Then
   Query_Stringstr="?"&Query_Stringstr
IF  instr(Server_Name,"www.")<1 Then 
   Response.Status = "301 Moved Permanently"
if instr(Path_infostr,"index")>0 or  instr(Path_infostr,"default")>0  Then
  Response.AddHeader "Location","http://www."&Server_Name
Else 
   Response.AddHeader "Location","http://www."&Server_Name&Path_infostr&Query_Stringstr 
End if
  Response.End
End if %>