将以下代码放到一个单独的页面checkcode.asp

<%Option ExplicitResponse.buffer=trueCall Com_CreatValidCode("validateCode") Sub Com_CreatValidCode(pSN)' 禁止缓存Response.Expires = -9999Response.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), vCodesFor i = 0 To 3vCode(i) = Int(Rnd * cAmount)vCodes = vCodes & Mid(cCode, vCode(i) + 1, 1)NextSession(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)ElseResponse.BinaryWrite vColorData(Mid(vNumberData(vCode(ii)), i * 10 + iii, 1))End IfNextNextNextEnd 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：

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

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