ASP. NET Verification Code Generation

Verification Code Generation Principle: generate a random character, generate the character into an image, and store it in the Session. Then, verify that the content entered by the user matches the verification code in the Session.
 
: You can click to switch the verification code information.
 
 
General handler: CheckCodeHandler. cs
 
1 <% @ WebHandler Language = "C #" Class = "CheckCodeHandler" %>
2
3 using System;
4 using System. Web;
5 using System. Text;
6 using System. Drawing;
7 using System. Web. SessionState;
8
9 public class CheckCodeHandler: IHttpHandler, IRequiresSessionState
10 {
11
12 // character set that generates the verification code
13 public string charcode = "2, 3, 4, 5, 6, 8, 9, A, B, C, D, E, F, G, H, J, K, M, N, P, r, S, U, W, X, Y, a, B, c, d, e, f, g, h, j, k, m, n, p, r, s, u, w, x, y ";
14
15 public void ProcessRequest (HttpContext context ){
16 string validateCode = CreateRandomCode (4 );
17 context. Session ["ValidateCode"] = validateCode; // Save the verification code to the session.
18 CreateCodeImage (validateCode, context );
19}
20
21 public bool IsReusable {
22 get {
23 return false;
24}
25}
26
27 /// <summary>
28 // generate the verification code
29 /// </summary>
30 /// <param name = "n"> Number of verification codes </param>
31 /// <returns> Verification code string </returns>
32 public string CreateRandomCode (int n)
33 {
34 string [] CharArray = charcode. Split (','); // convert a string to a character array
35 string randomCode = "";
36 int temp =-1;
37
38 Random rand = new Random ();
39 for (int I = 0; I <n; I ++)
40 {
41 if (temp! =-1)
42 {
43 rand = new Random (I * temp * (int) DateTime. Now. Ticks ));
44}
45 int t = rand. Next (CharArray. Length-1 );
46 if (temp! =-1 & temp = t)
47 {
48 return CreateRandomCode (n );
49}
50 temp = t;
51 randomCode + = CharArray [t];
52}
53 return randomCode;
54}
55
56 public void CreateCodeImage (string checkCode, HttpContext context)
57 {
58 int iwidth = (int) (checkCode. Length * 13 );
59 System. Drawing. Bitmap image = new System. Drawing. Bitmap (iwidth, 20 );
60 Graphics g = Graphics. FromImage (image );
61 Font f = new System. Drawing. Font ("Arial", 12, (System. Drawing. FontStyle. Italic | System. Drawing. FontStyle. Bold ));
62
63 // foreground
64 Brush B = new System. Drawing. SolidBrush (Color. Black );
65
66 // background color
67g. Clear (Color. White );
68
69 // fill in text
70g. DrawString (checkCode, f, B, 0, 1 );
71
72 // random line
73
74 Pen linePen = new Pen (Color. Gray, 0 );
75 Random rand = new Random ();
76
77 for (int I = 0; I <5; I ++)
78 {
79 int x1 = rand. Next (image. Width );
80 int y1 = rand. Next (image. Height );
81 int x2 = rand. Next (image. Width );
82 int y2 = rand. Next (image. Height );
83g. DrawLine (linePen, x1, y1, x2, y2 );
84}
85
86 // random point
87 for (int I = 0; I <30; I ++)
88 {
89 int x = rand. Next (image. Width );
90 int y = rand. Next (image. Height );
91 image. SetPixel (x, y, Color. Gray );
92}
93
94 // border
95g. DrawRectangle (new Pen (Color. Gray), 0, 0, image. Width-1, image. Height-1 );
96
97 // output image
98 System. IO. MemoryStream MS = new System. IO. MemoryStream ();
99 image. Save (MS, System. Drawing. Imaging. ImageFormat. Jpeg );
100 context. Response. ClearContent ();
101 context. Response. ContentType = "image/jpeg ";
102 context. Response. BinaryWrite (ms. ToArray ());
103g. Dispose ();
104 image. Dispose ();
105}
106}
 
 
Encapsulated as a Class Library: ValidateNumber. cs
 
1 using System;
2 using System. Collections. Generic;
3 using System. Linq;
4 using System. Web;
5 using System. Drawing;
6 using System. Web. UI;
7 using System. Drawing. Drawing2D;
8 using System. IO;
9 using System. Drawing. Imaging;
10
11 /// <summary>
12 // ValidateNumber
13 /// </summary>
14 public class ValidateNumber
15 {
16 // character set that generates the verification code (confusing characters are removed)
17 private string charcode = "2, 3, 4, 5, 6, 8, 9, A, B, C, D, E, F, G, H, J, K, M, N, P, r, S, U, W, X, Y, a, B, c, d, e, f, g, h, j, k, m, n, p, r, s, u, w, x, y ";
18
19 /// <summary>
20 /// Maximum length of the Verification Code
21 /// </summary>
22 public int MaxLength
23 {
24 get {return 10 ;}
25}
26
27 /// <summary>
28 /// minimum length of the Verification Code
29 /// </summary>
30 public int MinLength
31 {
32 get {return 1 ;}
33}
34
35 /// <summary>
36 // generate the verification code
37 /// </summary>
38 // <param name = "length"> specify the length of the Verification Code </param>
39 /// <returns> </returns>
40 public string CreateValidateNumber (int length)
41 {
42 string [] CharArray = charcode. Split (','); // convert a string to a character array
43 string randomCode = "";
44 int temp =-1;
45
46 Random rand = new Random ();
47 for (int I = 0; I <length; I ++)
48 {
49 if (temp! =-1)
50 {
51 rand = new Random (I * temp * (int) DateTime. Now. Ticks ));
52}
53 int t = rand. Next (CharArray. Length-1 );
54 if (temp! =-1 & temp = t)
55 {
56 return CreateValidateNumber (length );
57}
58 temp = t;
59 randomCode + = CharArray [t];
60}
61 return randomCode;
62}
63
64 /// <summary>
65 // create a verification code Image
66 /// </summary>
67 // <param name = "context"> context object </param>
68 // <param name = "validateNum"> Verification Code </param>
69 public void CreateValidateGraphic (HttpContext context, string validateNum)
70 {
71 int iwidth = (int) (validateNum. Length * 14 );
72 Bitmap image = new Bitmap (iwidth, 22 );
73 Graphics g = Graphics. FromImage (image );
74 try
75 {
76 // generate a random Generator
77 Random random = new Random ();
78 // clear the background color of the image
79g. Clear (Color. White );
80 // picture interference line
81 for (int I = 0; I <25; I ++)
82 {
83 int x1 = random. Next (image. Width );
84 int x2 = random. Next (image. Width );
85 int y1 = random. Next (image. Height );
86 int y2 = random. Next (image. Height );
87g. DrawLine (new Pen (Color. Silver), x1, y1, x2, y2 );
88}
89 Font font = new Font ("Arial", 12, (FontStyle. Bold | FontStyle. Italic ));
90 LinearGradientBrush brush = new LinearGradientBrush (new Rectangle (0, 0, image. Width, image. Height ),
91 Color. Blue, Color. DarkRed, 1.2f, true );
92g. DrawString (validateNum, font, brush, 3, 2 );
93 // foreground interference points
94 for (int I = 0; I <100; I ++)
95 {
96 int x = random. Next (image. Width );
97 int y = random. Next (image. Height );
98 image. SetPixel (x, y, Color. FromArgb (random. Next ()));
99}
100 // draw the border line of the image
101g. DrawRectangle (new Pen (Color. Silver), 0, 0, image. Width-1, image. Height-1 );
102 // Save image data
103 MemoryStream stream = new MemoryStream ();
104 image. Save (stream, ImageFormat. Jpeg );
105 // output image
106 context. Response. Clear ();
107 context. Response. ContentType = "image/jpeg ";
108 context. Response. BinaryWrite (stream. ToArray ());
109}
110 finally
111 {
112g. Dispose ();
113 image. Dispose ();
114}
115}
116 /// <summary>
117 // obtain the length of the Verification Code Image
118 /// </summary>
119 /// <param name = "validateNumLength"> Verification code length </param>
120 /// <returns> </returns>
121 public static int GetImageWidth (int validateNumLength)
122 {
123 return (int) (validateNumLength * 14 );
124}
125 /// <summary>
126 // obtain the height of the Verification Code Image
127 /// </summary>
128 /// <returns> </returns>
129 public static double GetImageHeight ()
130 {
131 return 22;
132}
133}
 
 
Example download: http://www.bkjia.com/uploadfile/2012/0528/20120528090736627.rar
 

 

 

Author: ForEvErNoME