如何通过ASP强制刷新网页和判断文件地址实例代码？

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'强制性刷新随机验证码
'让随机验证码每次按IE的后退按钮时，返回登录页面的随即码都自动刷新，
Response.expires=-1
Response.AddHeader"pragma","no-cache"
Response.AddHeader"cache-control","no-store"
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Response.Write("")
On Error Resume Next
Dim thisurl,thistext
thisurl=Request("thisurl") '定义文件地址(非Html格式文档)!
if thisurl="" then
Response.Write("请先输入文件地址!")
Response.End
End if
Function objxmlhttp(xmlurl)
On Error Resume Next
Set objxml = CreateObject("Microsoft.XMLHTTP")
objxml.Open "get",xmlurl,false
objxml.setrequestheader "content-type","application/x-www-form-urlencoded"
objxml.send
objxmlhttp = objxml.responsebody
if Err then
Err.Clear
Response.Write("建立连接失败,文件不存在或网络有问题!;错误原因:"&Err.Description&"！")
Response.End
End if
End Function
Function bytes2BSTR(vIn)
strReturn = ""
For i = 1 To LenB(vIn)
ThisCharCode = AscB(MidB(vIn,i,1))
If ThisCharCode < &H80 Then
strReturn = strReturn & Chr(ThisCharCode)
Else
NextCharCode = AscB(MidB(vIn,i+1,1))
strReturn = strReturn & Chr(CLng(ThisCharCode) * &H100 + CInt(NextCharCode))
i = i + 1
End If
Next
bytes2BSTR = strReturn
End Function
thisurl2=Split(thisurl,",")
For Each ii In thisurl2
thistext=bytes2BSTR(objxmlhttp(ii))
if InStr(thistext,"")<>0 then
Response.Write(""& ii &" ×
")
Else
Response.Write(""& ii &" √
")
End if
Next
if Err then
Err.Clear
Response.Write("碰到意外!;错误原因:"&Err.Description&"！")
Response.End
End if
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