Question

贴吧里那种，顶一次就变一次的图片是怎麼做的？什麼原理？

Answer 1

我把asp源码给你，自己看：

************************* 随机图片显示 ****************************
'使用实例:img.asp?list=图片存放目录
'使用注意:图片目录放于本文件同目录下!需要FSO支持!
'说明：只要将变化图片放于一个目录下，修改下面程序的（需要修改的地方）成你的目录名称！
上传本程序和图片文件夹到同一目录下，在发帖时候使用UBB代码形如：即可！
'----------------------------------------------------------------------------------------
Function AllPath()
Dim Domain,GFilePath
Domain = Request.ServerVariables("SERVER_NAME")
GFilePath = Request.ServerVariables("PATH_INFO")
GFilePath = lcase(left(GFilePath,instrRev(GFilePath,"/")))
AllPath = "http://"&Domain&GFilePath
End Function

Function ShowFileList(folderspec)
Dim Path,objFSO,objFolder,count,objFile,nume,S
Path = Server.MapPath(folderspec)
Set objFSO = Server.CreateObject("Scripting.FileSystemObject")
If objFSO.FolderExists(Path) Then
Set objFolder = objFSO.GetFolder(Path)
count = 0
For Each objFile in objFolder.Files
count = count+1
Next
randomize
nume = Int((count*rnd)+1)
S = 0
ShowFileList = ""
For Each objFile in objFolder.Files
S = S + 1
If S = nume Then
ShowFileList = objFile.Name
Exit For
End If
Next
Set objFolder = Nothing
Else
ShowFileList = "NO"
End If
Set objFSO = Nothing
End Function

Dim list,2004528115924.htm,address,str

list = trim(Request.QueryString("list"))
if list = "" then
Response.write "本页需要正确参数引入,您缺少相关的参数！正确格式如下："&AllPath&"img.asp?list=（需要修改的地方）"
Response.End()
end if

2004528115924.htm = ShowFileList("./"&list&"/")
if 2004528115924.htm = "NO" then
Response.write "您指定的目录<b>"&list&"</b>不存在，请重新指定！"
Response.End()
end if

if 2004528115924.htm = "" then
Response.write "您指定的目录<b>"&list&"</b>没有相关的图片文件存在，请重新指定！"
Response.End()
end if

str = right(2004528115924.htm,3)
if str<>"jpg" and str<>"gif" then
2004528115924.htm = "erro.gif"
end if

address = AllPath&list&"/"
address = address&2004528115924.htm
%>
<%Response.redirect(address)%>