ASP.NET 2.0 HttpHandler实现生成图片验证码 ，转

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 }