C#验证码技术示例

验证码生成页面：CheckCode.aspx

c# 代码

 

1. using System;
2. using System.Data;
3. using System.Configuration;
4. using System.Collections;
5. using System.Web;
6. using System.Web.Security;
7. using System.Web.UI;
8. using System.Web.UI.WebControls;
9. using System.Web.UI.WebControls.WebParts;
10. using System.Web.UI.HtmlControls;
11. using System.Drawing;
12. public partial class CheckCode : System.Web.UI.Page
13. {
14. protected void Page_Load(object sender, EventArgs e)
15. {
16. this.CreateCheckCodeImage(GenerateCheckCode());
17.  
18. }
19. private string GenerateCheckCode()
20. {
21. int number;
22. char code;
23. string checkCode = String.Empty;
24.  
25. System.Random random = new Random();
26.  
27. for (int i = 0; i < 5; i++)
28. {
29. number = random.Next();
30.  
31. if (number % 2 == 0)
32. code = (char)(0 + (char)(number % 10));
33. else
34. code = (char)(A + (char)(number % 26));
35.  
36. checkCode += code.ToString();
37. }
38.  
39. Response.Cookies.Add(new HttpCookie("CheckCode", checkCode));
40.  
41. return checkCode;
42. }
43.  
44. private void CreateCheckCodeImage(string checkCode)
45. {
46. if (checkCode == null || checkCode.Trim() == String.Empty)
47. return;
48.  
49. System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), 22);
50. Graphics g = Graphics.FromImage(image);
51.  
52. try
53. {
54. //生成随机生成器
55. Random random = new Random();
56.  
57. //清空图片背景色
58. g.Clear(Color.White);
59.  
60. //画图片的背景噪音线
61. for (int i = 0; i < 25; i++)
62. {
63. int x1 = random.Next(image.Width);
64. int x2 = random.Next(image.Width);
65. int y1 = random.Next(image.Height);
66. int y2 = random.Next(image.Height);
67.  
68. g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
69. }
70.  
71. Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));
72. System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);
73. g.DrawString(checkCode, font, brush, 2, 2);
74.  
75. //画图片的前景噪音点
76. for (int i = 0; i < 100; i++)
77. {
78. int x = random.Next(image.Width);
79. int y = random.Next(image.Height);
80.  
81. image.SetPixel(x, y, Color.FromArgb(random.Next()));
82. }
83.  
84. //画图片的边框线
85. g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
86.  
87. System.IO.MemoryStream ms = new System.IO.MemoryStream();
88. image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
89. Response.ClearContent();
90. Response.ContentType = "image/Gif";
91. Response.BinaryWrite(ms.ToArray());
92. }
93. finally
94. {
95. g.Dispose();
96. image.Dispose();
97. }
98. }
99.  
100.  
101.  
102. }

而在目标页面调用是用这样的：



如果判断验证码呢，下面一段就是判断语句

c# 代码

 

1. protected void btnSaveAs_Click(object sender, EventArgs e)
2. {
3. if (Request.Cookies["CheckCode"] == null)
4. {
5. lblMessage.Text = "您的浏览器设置已被禁用 Cookies，您必须设置浏览器允许使用 Cookies 选项后才能使用本系统。";
6. lblMessage.Visible = true;
7. return;
8. }
9.  
10. if (String.Compare(Request.Cookies["CheckCode"].Value, txtCheckCode.Text, true) != 0)
11. {
12. lblMessage.Text = "验证码错误，请输入正确的验证码。";
13. lblMessage.Visible = true;
14. return;
15. }
16. }

转载于:https://www.cnblogs.com/gllgsoft/archive/2008/08/06/1262177.html