利用stream直接下载文件

在浏览器的地址栏里直接输入一个doc或xls或jpg的文件的url路径，那么该文件会直接显示在浏览器里。而在很多时候我们希望能直接弹出下载提示框让用户下载，我们该怎么办呢？这里有两种方法：

1、设置你的服务器的iis，给doc等后缀名做映射

2、在向客户端发送时设置其contenttype



下面详细说明方法2



<%

Response.Buffer = true

Response.Clear



dim url

Dim fso,fl,flsize

dim Dname

Dim objStream,ContentType,flName,isre,url1

'*********************************************调用时传入的下载文件名

Dname=trim(request("n"))

'******************************************************************

If Dname<>"" Then

'******************************下载文件存放的服务端目录

url=server.MapPath("/")&"\"&Dname

'***************************************************

End If



Set fso=Server.CreateObject("Scripting.FileSystemObject")

Set fl=fso.getfile(url)

flsize=fl.size

flName=fl.name

Set fl=Nothing

Set fso=Nothing

%>

<%

Set objStream = Server.CreateObject("ADODB.Stream")

objStream.Open

objStream.Type = 1

objStream.LoadFromFile url





Select Case lcase(Right(flName, 4))

Case ".asf"

ContentType = "video/x-ms-asf"

Case ".avi"

ContentType = "video/avi"

Case ".doc"

ContentType = "application/msword"

Case ".zip"

ContentType = "application/zip"

Case ".xls"

ContentType = "application/vnd.ms-excel"

Case ".gif"

ContentType = "image/gif"

Case ".jpg", "jpeg"

ContentType = "image/jpeg"

Case ".wav"

ContentType = "audio/wav"

Case ".mp3"

ContentType = "audio/mpeg3"

Case ".mpg", "mpeg"

ContentType = "video/mpeg"

Case ".rtf"

ContentType = "application/rtf"

Case ".htm", "html"

ContentType = "text/html"

Case ".txt"

ContentType = "text/plain"

Case Else

ContentType = "application/octet-stream"

End Select







Response.AddHeader "Content-Disposition", "attachment; filename=" & flName

Response.AddHeader "Content-Length", flsize



Response.Charset = "UTF-8"

Response.ContentType = ContentType



Response.BinaryWrite objStream.Read

Response.Flush

response.Clear()

objStream.Close

Set objStream = Nothing



%>



将下面的东西存成download.asp然后你就可以用<a herf="http://xxx.xxx.com/download.asp?n=file.doc";>download!</a>来下载同一目录下的file.doc了!



但是这里有个问题就是直接将file.doc路径写在url里是不安全的，所以解决方案应该是将file.doc的路径存到数据库里，同过查找数据库后得到路径



在这个程序的最前面如果加上一个判断：



if instr(Request.ServerVariables("HTTP_REFERER"),"http://你的域名")=0 then

Response.End

end if



就能够很好的防止别人的盗链了