ASP使用流输出文件下载

function downloadfile(fullpath)
downloadfile = false
dim strfilename, s, fso, f, intfilelength 
set fso = server.createobject("scripting.filesystemobject") 
if not fso.fileexists(fullpath) then  
exit function  
end if     
set f = fso.getfile(fullpath) 
       '获取文件大小   
       intfilelength = f.size   
       set s = server.createobject("adodb.stream")  
       s.open     
       s.type = 1    
       s.loadfromfile(fullpath)    
       response.buffer = true     
       response.clear     
       'response.addheader "content-type","application/x-msdownload"  
       response.addheader "content-disposition","attachment;filename=" & f.name    
       response.addheader "content-length" ,intfilelength     
       response.contenttype = "application/octet-stream"    
       while not s.eos       
       response.binarywrite s.read(1024 * 64)    
       response.flush    
       wend     
       s.close  
       set s = nothing   
       downloadfile = true  
end function