保存下面代码到code.asp,在需要显示验证码的地方使用
来显示,使用session("getcode") 来提取验证码

如果需要使用点击一下更换图片的效果，可以使用：

<%
option explicit
response.buffer=true
call com_creatvalidcode("getcode")
sub com_creatvalidcode(psn)
response.expires = -1
response.addheader "pragma","no-cache"
response.addheader "cache-ctrol","no-cache"
response.contenttype = "image/bmp"
randomize
dim i, ii, iii
const codds = 6 ' 杂点出现的机率
const camount = 10 ' 文字数量
const ccode = "0123456789abcd"
' 颜色的数据(字符，背景)
dim vcolordata(1)
vcolordata(0) = chrb(0) & chrb(0) & chrb(255) ' 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) = "1110000111110111101111011110111101001011110100101111010010111101001011110111101111011110111110000111"
vnumberdata(1) = "1111011111110001111111110111111111011111111101111111110111111111011111111101111111110111111100000111"
vnumberdata(2) = "1110000111110111101111011110111111111011111111011111111011111111011111111011111111011110111100000011"
vnumberdata(3) = "1110000111110111101111011110111111110111111100111111111101111111111011110111101111011110111110000111"
vnumberdata(4) = "1111101111111110111111110011111110101111110110111111011011111100000011111110111111111011111111000011"
vnumberdata(5) = "1100000011110111111111011111111101000111110011101111111110111111111011110111101111011110111110000111"
vnumberdata(6) = "1111000111111011101111011111111101111111110100011111001110111101111011110111101111011110111110000111"
vnumberdata(7) = "1100000011110111011111011101111111101111111110111111110111111111011111111101111111110111111111011111"
vnumberdata(8) = "1110000111110111101111011110111101111011111000011111101101111101111011110111101111011110111110000111"
vnumberdata(9) = "1110001111110111011111011110111101111011110111001111100010111111111011111111101111011101111110001111"
' 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
%>