这个程序主要是先生成一个随机数，然后根据生成的随机数经过变换后作为XBM图片的内容，最后显示这个图片. 验证时中要获取输入的数字和Session("validatecode")比较，如果相等则通过验证（还要注意一下相比较的两数据的类型保持一致）。
如何显示生成的图片呢？
1<img src="xbm.asp"/>
关于XBM图的格式信息，看这里
http://www.zdnet.com.cn/developer/tech/story/0,2000081602,39134972,00.htm
xbm.asp的代码如下
程序代码：
1
2'开启缓冲
3Response.Buffer = True
4With Response
5.Expires = -1
6.AddHeader "Pragma","no-cache"
7.AddHeader "cache-ctrol","no-cache"
8End With
9
10Dim num
11Randomize
12num = Int(7999 * Rnd + 2000)
13Session("validateCode") = num
14
15Dim Image
16Dim Width, Height
17Dim digtal
18Dim Length
19Dim sort
20Dim hc
21Length = 4
22hc = chr(13) & chr(10)
23
24Redim sort(Length)
25
26digital = ""
27For I = 1 To Length - Len(num)
28digital = digital & "0"
29Next
30For I = 1 To Len(num)
31digital = digital & Mid(num, I, 1)
32Next
33For I = 1 To Len(digital)
34sort(I) = Mid(digital, I, 1)
35Next
36Width = 8 * Len(digital)
37Height = 10
38
39Response.ContentType = "image/x-xbitmap"
40
41Image = "#define counter_width " & Width & hc
42Image = Image & "#define counter_height " & Height & hc
43Image = Image & "static unsigned char counter_bits[] = {" & hc
44
45For I = 1 To Height
46For J = 1 To Length
47Image = Image & a(sort(J),I) & ","
48Next
49Next
50
51Image = Left(Image, Len(Image) - 1)
52Image = Image & "};" & hc
53
54Response.Write Image
Numcode.asp的代码如下：
程序代码：
1
2Dim a(10,10)
3a(0,1) = "0x3c" '数字0
4a(0,2) = "0x66"
5a(0,3) = "0xc3"
6a(0,4) = "0xc3"
7a(0,5) = "0xc3"
8a(0,6) = "0xc3"
9a(0,7) = "0xc3"
10a(0,8) = "0xc3"
11a(0,9) = "0x66"
12a(0,10)= "0x3c"
13a(1,1) = "0x18" '数字1
14a(1,2) = "0x1c"
15a(1,3) = "0x18"
16a(1,4) = "0x18"
17a(1,5) = "0x18"
18a(1,6) = "0x18"
19a(1,7) = "0x18"
20a(1,8) = "0x18"
21a(1,9) = "0x18"
22a(0,10)= "0x7e"
23a(2,1) = "0x3c" '数字2
24a(2,2) = "0x66"
25a(2,3) = "0x60"
26a(2,4) = "0x60"
27a(2,5) = "0x30"
28a(2,6) = "0x18"
29a(2,7) = "0x0c"
30a(2,8) = "0x06"
31a(2,9) = "0x06"
32a(2,10)= "0x7e"
33a(3,1) = "0x3c" '数字3
34a(3,2) = "0x66"
35a(3,3) = "0xc0"
36a(3,4) = "0x60"
37a(3,5) = "0x1c"
38a(3,6) = "0x60"
39a(3,7) = "0xc0"
40a(3,8) = "0xc0"
41a(3,9) = "0x66"
42a(3,10)= "0x38"
43a(4,1) = "0x38" '数字4
44a(4,2) = "0x3c"
45a(4,3) = "0x36"
46a(4,4) = "0x33"
47a(4,5) = "0x33"
48a(4,6) = "0x33"
49a(4,7) = "0xff"
50a(4,8) = "0x30"
51a(4,9) = "0x30"
52a(4,10)= "0xfe"
53a(5,1) = "0xfe" '数字5
54a(5,2) = "0xfe"
55a(5,3) = "0x06"
56a(5,4) = "0x06"
57a(5,5) = "0x3e"
58a(5,6) = "0x60"
59a(5,7) = "0xc0"
60a(5,8) = "0xc3"
61a(5,9) = "0x66"
62a(5,10)= "0x3c"
63a(6,1) = "0x60" '数字6
64a(6,2) = "0x30"
65a(6,3) = "0x18"
66a(6,4) = "0x0c"
67a(6,5) = "0x3e"
68a(6,6) = "0x63"
69a(6,7) = "0xc3"
70a(6,8) = "0xc3"
71a(6,9) = "0x66"
72a(6,10) ="0x3c"
73a(7,1) = "0xff" '数字7
74a(7,2) = "0xc0"
75a(7,3) = "0x60"
76a(7,4) = "0x30"
77a(7,5) = "0x18"
78a(7,6) = "0x18"
79a(7,7) = "0x18"
80a(7,8) = "0x18"
81a(7,9) = "0x18"
82a(7,10)= "0x18"
83a(8,1) = "0x3c" '数字8
84a(8,2) = "0x66"
85a(8,3) = "0xc3"
86a(8,4) = "0x66"
87a(8,5) = "0x3c"
88a(8,6) = "0x66"
89a(8,7) = "0xc3"
90a(8,8) = "0xc3"
91a(8,9) = "0x66"
92a(8,10)= "0x3c"
93a(9,1) = "0x3c" '数字9
94a(9,2) = "0x66"
95a(9,3) = "0xc3"
96a(9,4) = "0xc3"
97a(9,5) = "0x66"
98a(9,6) = "0x3c"
99a(9,7) = "0x18"
100a(9,8) = "0x0c"
101a(9,9) = "0x06"
102a(9,10)= "0x03"