将以下代码放到一个单独的页面checkcode.asp 

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<%
Option Explicit
Response.buffer=true
Call Com_CreatValidCode("validateCode")
 
Sub Com_CreatValidCode(pSN)
' 禁止缓存
Response.Expires = -9999
Response.AddHeader "Pragma","no-cache"
Response.AddHeader "cache-ctrol","no-cache"
Response.ContentType = "Image/BMP"
 
Randomize
 
Dim i, ii, iii
 
Const cOdds = 2 ' 杂点出现的机率
Const cAmount = 10 ' 文字数量
Const cCode = "0123456789"
 
' 颜色的数据(字符,背景)
Dim vColorData(1)
vColorData(0) = ChrB(0) & ChrB(0) & ChrB(211) ' 蓝0,绿0,红0(黑色)
vColorData(1) = ChrB(255) & ChrB(255) & ChrB(255) ' 蓝250,绿236,红211(浅蓝色)
 
' 随机产生字符
Dim vCode(4), vCodes
For i = 0 To 3
vCode(i) = Int(Rnd * cAmount)
vCodes = vCodes & Mid(cCode, vCode(i) + 1, 1)
Next
Session(pSN) = vCodes '记录入Session
' 字符的数据
Dim vNumberData(9)
vNumberData(0) =
 
"1110000111110111101111011110111101001011110100101111010010111101001011110111101111011110111
 
110000111"
vNumberData(1) =
 
"1111011111110001111111110111111111011111111101111111110111111111011111111101111111110111111
 
100000111"
vNumberData(2) =
 
"1110000111110111101111011110111111111011111111011111111011111111011111111011111111011110111
 
100000011"
vNumberData(3) =
 
"1110000111110111101111011110111111110111111100111111111101111111111011110111101111011110111
 
110000111"
vNumberData(4) =
 
"1111101111111110111111110011111110101111110110111111011011111100000011111110111111111011111
 
111000011"
vNumberData(5) =
 
"1100000011110111111111011111111101000111110011101111111110111111111011110111101111011110111
 
110000111"
vNumberData(6) =
 
"1111000111111011101111011111111101111111110100011111001110111101111011110111101111011110111
 
110000111"
vNumberData(7) =
 
"1100000011110111011111011101111111101111111110111111110111111111011111111101111111110111111
 
111011111"
vNumberData(8) =
 
"1110000111110111101111011110111101111011111000011111101101111101111011110111101111011110111
 
110000111"
vNumberData(9) =
 
"1110001111110111011111011110111101111011110111001111100010111111111011111111101111011101111
 
110001111"
' 输出图像文件头
Response.BinaryWrite ChrB(66) & ChrB(77) & ChrB(230) & ChrB(4) & ChrB(0) & ChrB(0) & ChrB(0)
 
& ChrB(0) &_
ChrB(0) & ChrB(0) & ChrB(54) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(40) & ChrB(0) &_
ChrB(0) & ChrB(0) & ChrB(40) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(10) & ChrB(0) &_
ChrB(0) & ChrB(0) & ChrB(1) & ChrB(0)
 
' 输出图像信息头
Response.BinaryWrite ChrB(24) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(176)
 
& ChrB(4) &_
ChrB(0) & ChrB(0) & ChrB(18) & ChrB(11) & ChrB(0) & ChrB(0) & ChrB(18) & ChrB(11) &_
ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) &_
ChrB(0) & ChrB(0)
 
For i = 9 To 0 Step -1 ' 历经所有行
For ii = 0 To 3 ' 历经所有字
For iii = 1 To 10 ' 历经所有像素
' 逐行、逐字、逐像素地输出图像数据
If Rnd * 99 + 1 < cOdds Then ' 随机生成杂点
Response.BinaryWrite vColorData(0)
Else
Response.BinaryWrite vColorData(Mid(vNumberData(vCode(ii)), i * 10 + iii, 1))
End If
Next
Next
Next
End Sub
%>

需要用得页面用如下方式引用: 

验证码:  src="checkcode.asp " alt="验证码,看不清楚?请点击刷新验证码" height="10" style="cursor : 
pointer;" onClick="this.src='checkcode.asp?t='+(new Date().getTime());" > 

判断页面: 

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<%
if trim(session("validateCode")) <> trim(Request("txt_check")) then
ErrorMessage = "请输入正确的验证码"
response.write(" <script>alert('"&ErrorMessage&"');location.href='Default.asp' </script>")
response.end
end if
%>

以上所述就是本文的全部内容了,希望大家能够喜欢。