1 <%@ WebHandler Language="C#" Class="ValidateImageHandler" %>
2
3 using System;
4 using System.Web;
5 using System.Web.SessionState;
6 using System.Drawing;
7 using System.Drawing.Imaging;
8 using System.Text;
9
10 ///

11 /// ValidateImageHandler 生成网站验证码功能
12 ///

13 public class ValidateImageHandler : IHttpHandler, IRequiresSessionState
14 {
15 int intLength = 5; //长度
16 string strIdentify = "Identify"; //随机字串存储键值，以便存储到Session中
17 public ValidateImageHandler()
18 {
19 }
20
21 ///

22 /// 生成验证图片核心代码
23 ///

24 ///
25 public void ProcessRequest(HttpContext hc)
26 {
27 //设置输出流图片格式
28 hc.Response.ContentType = "image/gif";
29
30 Bitmap b = new Bitmap(200, 60);
31 Graphics g = Graphics.FromImage(b);
32 g.FillRectangle(new SolidBrush(Color.YellowGreen), 0, 0, 200, 60);
33 Font font = new Font(FontFamily.GenericSerif, 48, FontStyle.Bold, GraphicsUnit.Pixel);
34 Random r = new Random();
35
36 //合法随机显示字符列表
37 string strLetters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";
38 StringBuilder s = new StringBuilder();
39
40 //将随机生成的字符串绘制到图片上
41 for (int i = 0; i < intLength; i++)
42 {
43 s.Append(strLetters.Substring(r.Next(0, strLetters.Length - 1), 1));
44 g.DrawString(s[s.Length - 1].ToString(), font, new SolidBrush(Color.Blue), i * 38, r.Next(0, 15));
45 }
46
47 //生成干扰线条
48 Pen pen = new Pen(new SolidBrush(Color.Blue), 2);
49 for (int i = 0; i < 10; i++)
50 {
51 g.DrawLine(pen, new Point(r.Next(0, 199), r.Next(0, 59)), new Point(r.Next(0, 199), r.Next(0, 59)));
52 }
53 b.Save(hc.Response.OutputStream, ImageFormat.Gif);
54 hc.Session[strIdentify] = s.ToString(); //先保存在Session中，验证与用户输入是否一致
55 hc.Response.End();
56
57 }
58
59 ///

60 /// 表示此类实例是否可以被多个请求共用(重用可以提高性能)
61 ///

62 public bool IsReusable
63 {
64 get
65 {
66 return true;
67 }
68 }
69 }
70