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生成验证码

 1 <!DOCTYPE html>
 2 <html xmlns="http://www.w3.org/1999/xhtml">
 3 <head>
 4 <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
 5     <title></title>
 6 </head>
 7 <body>
 8     <table>
 9         <tr>
10             <td>用户名：</td>
11             <td><input type="text" /></td>
12         </tr>
13         <tr>
14             <td>密码：</td>
15             <td><input type="password" /></td>
16         </tr>
17         <tr>
18             <td>验证码</td>
19             <td><img src="ValidCode.ashx" /></td>
20         </tr>
21         <tr></tr>
22     </table>
23 </body>
24 </html>

View Code

ValidCode.ashx

 1 <%@ WebHandler Language="C#" Class="ValidCode" %>
 2 
 3 using System;
 4 using System.Web;
 5 using System.Drawing;
 6 
 7 public class ValidCode : IHttpHandler
 8 {
 9 
10     public void ProcessRequest(HttpContext context)
11     {
12         context.Response.ContentType = "image/jpeg";
13         //生成随机验证码的字符串
14         string code = MakeRanStr();
15         using (Image img = new Bitmap(100, 26))
16         {
17             using (Graphics g = Graphics.FromImage(img))
18             {
19                 //背景为白色
20                 g.Clear(Color.White);
21                 //验证码边框
22                 g.DrawRectangle(Pens.Black, new Rectangle(0, 0, img.Width - 1, img.Height - 1));
23                 //干扰线
24                 DrwaGanRaoXian(50, g, img);
25                 g.DrawString(code, new Font("微软雅黑", 12), Brushes.Red, 1, 2);                
26             }
27             img.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
28         }
29     }
30 
31     /// <summary>
32     /// 画干扰线
33     /// </summary>
34     void DrwaGanRaoXian(int count, Graphics g, Image img)
35     {
36         Random ran = new Random();
37         for (int i = 0; i < count; i++)
38         {
39             Point p1 = new Point(ran.Next(img.Width), ran.Next(img.Height));
40             Point p2 = new Point(p1.X - ran.Next(-50, 50), p1.Y - ran.Next(-50, 50));
41             g.DrawLine(Pens.Black, p1, p2);
42         }
43     }
44 
45     /// <summary>
46     /// 生成随机码
47     /// </summary>
48     /// <returns></returns>
49     string MakeRanStr()
50     {
51         char[] charArr = new char[10] { 'a', 'b', 'c', '1', '2', '3', '你', '好', '啊', '呀' };
52         string strValidCode = "";
53         Random ran = new Random();
54         int index = 0;
55         for (int i = 0; i < 5; i++)
56         {
57             index = ran.Next(9);
58             strValidCode += charArr[index];
59         }
60         return strValidCode;
61     }
62 
63     public bool IsReusable
64     {
65         get
66         {
67             return false;
68         }
69     }
70 
71 }

View Code

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原文地址：https://www.cnblogs.com/HuoAA/p/4087935.html