ASP.NET2.0HttpHandler实现生成图片验证码（转）

OStack程序员社区-中国程序员成长平台 › 门户 › 编程› ASP.NET›ASP.NET编程经验

原作者: [db:作者] 来自: [db:来源] 收藏邀请

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 /// <summary>
11 /// ValidateImageHandler 生成网站验证码功能
12 /// </summary>
13 public class ValidateImageHandler : IHttpHandler, IRequiresSessionState  //特别注意，如果需要读写Session，则必须继承于IRequiresSessionState接口
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     /// <summary>
22     ///  生成验证图片核心代码
23     /// </summary>
24     /// <param name="hc"></param>
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     }