动态生成验证码

知识点：

1. 对图像的操作

问题：

解决方案

 1 <%@ WebHandler Language="C#" Class="ValidateCode" %>
 2
 3 using System;
 4 using System.Web;
 5 using System.Drawing;
 6 using System.IO;
 7
 8 public class ValidateCode : IHttpHandler {
 9
10     public void ProcessRequest (HttpContext context) {
11         context.Response.ContentType = "text/plain";
12         //context.Response.Write("Hello World");
13         Random r = new Random();
14         int n = r.Next(10000,100000);
15         CreateValidateGraphic(n.ToString(),context);
16     }
17     /// <summary>
18     /// 创建验证码的图片
19     /// </summary>
20     /// <param name="containsPage">要输出到的page对象</param>
21     /// <param name="validateNum">验证码</param>
22     public void CreateValidateGraphic(string validateCode, HttpContext context)
23     {
24         Bitmap image = new Bitmap((int)Math.Ceiling(validateCode.Length * 12.0), 22);
25         Graphics g = Graphics.FromImage(image);
26         try
27         {
28             //生成随机生成器
29             Random random = new Random();
30             //清空图片背景色
31             g.Clear(Color.White);
32             //画图片的干扰线
33             for (int i = 0; i < 25; i++)
34             {
35                 int x1 = random.Next(image.Width);
36                 int x2 = random.Next(image.Width);
37                 int y1 = random.Next(image.Height);
38                 int y2 = random.Next(image.Height);
39                 g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
40             }
41             Font font = new Font("Arial", 12, (FontStyle.Bold | FontStyle.Italic));
42             System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),
43              Color.Blue, Color.DarkRed, 1.2f, true);
44             g.DrawString(validateCode, font, brush, 3, 2);
45             //画图片的前景干扰点
46             for (int i = 0; i < 100; i++)
47             {
48                 int x = random.Next(image.Width);
49                 int y = random.Next(image.Height);
50                 image.SetPixel(x, y, Color.FromArgb(random.Next()));
51             }
52             //画图片的边框线
53             g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
54             //保存图片数据
55             MemoryStream stream = new MemoryStream();
56             image.Save(stream, System.Drawing.Imaging.ImageFormat.Jpeg);
57             //输出图片流
58             context.Response.Clear();
59             context.Response.ContentType = "image/jpeg";
60             context.Response.BinaryWrite(stream.ToArray());
61         }
62         finally
63         {
64             g.Dispose();
65             image.Dispose();
66         }
67     }
68
69     public bool IsReusable {
70         get {
71             return false;
72         }
73     }
74
75 }