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ASP.NET 2.0 HttpHandler实现生成图片验证码(示例代码下载)

2008-03-11 09:46 696 查看
 学习整理了一下(一).功能       用HttpHandler实现图片验证码     

 (二).代码如下  1. 处理程序文件 ValidateImageHandler.ashx代码如下  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 
 2. 前台页面代码
 1 
 2             
 3             
 4             
 5              6                 Font-Names="Verdana" Font-Size="0.8em" ForeColor="#284E98" />
 7             
 8                 
 9                     
10                         
11                             
12                                 
13                                     14                                         background-color: #507cd1">
15                                         登录
16                                 
17                                 
18                                     
19                                         用户名:
20                                     
21                                         
22                                         23                                             ErrorMessage="必须填写“用户名”。" ToolTip="必须填写“用户名”。" ValidationGroup="Login1">*
24                                     
25                                 
26                                 
27                                     
28                                         密码:
29                                     
30                                         
31                                         32                                             ErrorMessage="必须填写“密码”。" ToolTip="必须填写“密码”。" ValidationGroup="Login1">*
33                                     
34                                 
35                                 
36                                     
37                                         验证码:
38                                     
39                                          
40                                         
                                 


                                       
41                                 
42                                 
43                                     
44                                          
45                                 
46                                 
47                                     
48                                         49                                             BorderStyle="Solid" BorderWidth="1px" CommandName="Login" Font-Names="Verdana"
50                                             Font-Size="0.8em" ForeColor="#284E98" Text="登录" ValidationGroup="Login1" />
51                                     
52                                 
53                             
54                         
55                     
56                 
57             

58         
59         
60 
  3.这里因为使用的是默认 *.asah处理文件类型,在machine.config文件中已经有此类型的默认注册,
 因为这里不需要注册 1 
2   


 注意:
1.再注册一下也不会出错,会覆盖machine.config文件配置
2.如果在同一个配置文件中注册多次,默认后者也会覆盖前者.
3.如果其它格式(系统默认没有注册)的,务必要在Web.config文件中注册一下.
 (三).示例代码下载            http://www.cnblogs.com/Files/ChengKing/ValidateImageHttpHandler.rar
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