用asp隐藏文件路径实现防盗链_asp实例

　　如果我们知道一个静态文件的实际路径如：http://www.xx.com/download/51windows.pdf，如果服务器没有作特别的限制设置，我们就可以毫不费力的把它下载下来！当网站提供51windows.pdf下载时，怎么样才能让下载者无法得到他的实际路径呢！本文就来介绍如何使用Asp来隐藏文件的实际下载路径。

　　我们在管理网站文件时，可以把扩展名一样的文件放在同一个目录下，起一个比较特别名字，例如放pdf文件目录为the_pdf_file_s，把下面代码另存为down.asp，他的网上路径为http://www.xx.com/down.asp，我们就可以用http://www.xx.com/down.asp?FileName=51windows.pdf来下载这个文件了，而且下载者无法看到这个文件实际下载路径的！在down.asp中我们还可以设置下载文件是否需要登陆，判断下载的来源页是否为外部网站，从而可以做到防止文件被盗链。

示例代码：

<%<br /> From_url = Cstr(Request.ServerVariables(“HTTP_REFERER”))<br /> Serv_url = Cstr(Request.ServerVariables(“SERVER_NAME”))<br /> if mid(From_url,8,len(Serv_url)) <> Serv_url then<br /> response.write “非法链接！” 防止盗链<br /> response.end<br /> end if</p> <p>if Request.Cookies(“Logined”)=”” then<br /> response.redirect “/login.asp” 需要登陆！<br /> end if<br /> Function GetFileName(longname)/folder1/folder2/file.asp=>file.asp<br /> while instr(longname,”/”)<br /> longname = right(longname,len(longname)-1)<br /> wend<br /> GetFileName = longname<br /> End Function<br /> Dim Stream<br /> Dim Contents<br /> Dim FileName<br /> Dim TrueFileName<br /> Dim FileExt<br /> Const adTypeBinary = 1<br /> FileName = Request.QueryString(“FileName”)<br /> if FileName = “” Then<br /> Response.Write “无效文件名！”<br /> Response.End<br /> End if<br /> FileExt = Mid(FileName, InStrRev(FileName, “.”) + 1)<br /> Select Case UCase(FileExt)<br /> Case “ASP”, “ASA”, “ASPX”, “ASAX”, “MDB”<br /> Response.Write “非法操作！”<br /> Response.End<br /> End Select<br /> Response.Clear<br /> if lcase(right(FileName,3))=”gif” or lcase(right(FileName,3))=”jpg” or lcase(right(FileName,3))=”png” then<br /> Response.ContentType = “image/*” 对图像文件不出现下载对话框<br /> else<br /> Response.ContentType = “application/ms-download”<br /> end if<br /> Response.AddHeader “content-disposition”, “attachment; filename=” & GetFileName(Request.QueryString(“FileName”))<br /> Set Stream = server.CreateObject(“ADODB.Stream”)<br /> Stream.Type = adTypeBinary<br /> Stream.Open<br /> if lcase(right(FileName,3))=”pdf” then 设置pdf类型文件目录<br /> TrueFileName = “/the_pdf_file_s/”&FileName<br /> end if<br /> if lcase(right(FileName,3))=”doc” then 设置DOC类型文件目录<br /> TrueFileName = “/my_D_O_C_file/”&FileName<br /> end if<br /> if lcase(right(FileName,3))=”gif” or lcase(right(FileName,3))=”jpg” or lcase(right(FileName,3))=”png” then<br /> TrueFileName = “/all_images_/”&FileName 设置图像文件目录<br /> end if<br /> Stream.LoadFromFile Server.MapPath(TrueFileName)<br /> While Not Stream.EOS<br /> Response.BinaryWrite Stream.Read(1024 * 64)<br /> Wend<br /> Stream.Close<br /> Set Stream = Nothing<br /> Response.Flush<br /> Response.End<br /> %>