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

2007年01月05日 21:04:00

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 /// >summary<
11 /// ValidateImageHandler 生成网站验证码功能
12 /// >/summary<
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 /// >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 }
58
59 /// >summary<
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 /// >/summary<
62 public bool IsReusable
63 {
64 get
65 {
66 return true ;
67 }
68 }
69 }
70

2. 前台页面代码

1 > asp:Login ID = " Login1 " runat = " server " BackColor = " #EFF3FB " BorderColor = " #B5C7DE " BorderPadding = " 4 " BorderStyle = " Solid " BorderWidth = " 1px " Font - Names = " Verdana " Font - Size = " 0.8em " ForeColor = " #333333 " OnAuthenticate = " Login1_Authenticate " <
2 > TitleTextStyle BackColor = " #507CD1 " Font - Bold = " True " Font - Size = " 0.9em " ForeColor = " White " /<
3 > InstructionTextStyle Font - Italic = " True " ForeColor = " Black " /<
4 > TextBoxStyle Font - Size = " 0.8em " /<
5 > LoginButtonStyle BackColor = " White " BorderColor = " #507CD1 " BorderStyle = " Solid " BorderWidth = " 1px "
6 Font - Names = " Verdana " Font - Size = " 0.8em " ForeColor = " #284E98 " /<
7 > LayoutTemplate <
8 > table border = " 0 " cellpadding = " 4 " cellspacing = " 0 " style = " border-collapse: collapse " <
9 > tr <
10 > td style = " width: 292px " <
11 > table border = " 0 " cellpadding = " 0 " <
12 > tr <
13 > td align = " center " colspan = " 2 " style = " font-weight: bold; font-size: 0.9em; color: white;
14 background - color: #507cd1 " <
15 登录 >/ td <
16 >/ tr <
17 > tr <
18 > td align = " left " style = " width: 84px; height: 31px; " <
19 > asp:Label ID = " UserNameLabel " runat = " server " AssociatedControlID = " UserName " < 用户名: >/ asp:Label <>/ td <
20 > td style = " height: 31px; width: 215px; " <
21 > asp:TextBox ID = " UserName " runat = " server " Font - Size = " 0.8em " Width = " 113px " <>/ asp:TextBox <
22 > asp:RequiredFieldValidator ID = " UserNameRequired " runat = " server " ControlToValidate = " UserName "
23 ErrorMessage = " 必须填写"用户名"。 " ToolTip = " 必须填写"用户名"。 " ValidationGroup = " Login1 " <*>/ asp:RequiredFieldValidator <
24 >/ td <
25 >/ tr <
26 > tr <
27 > td align = " left " style = " width: 84px " <
28 > asp:Label ID = " PasswordLabel " runat = " server " AssociatedControlID = " Password " < 密码: >/ asp:Label <>/ td <
29 > td style = " width: 215px " <
30 > asp:TextBox ID = " Password " runat = " server " Font - Size = " 0.8em " TextMode = " Password " <>/ asp:TextBox <
31 > asp:RequiredFieldValidator ID = " PasswordRequired " runat = " server " ControlToValidate = " Password "
32 ErrorMessage = " 必须填写"密码"。 " ToolTip = " 必须填写"密码"。 " ValidationGroup = " Login1 " <*>/ asp:RequiredFieldValidator <
33 >/ td <
34 >/ tr <
35 > tr <
36 > td style = " width: 84px; height: 4px; " align = " left " <
37 验证码: >/ td <
38 > td valign = " middle " style = " height: 31px; width: 215px; " align = " left " <
39 > asp:TextBox ID = " TextBox1 " runat = " server " Font - Size = " 0.8em " TextMode = " Password " <>/ asp:TextBox <& nbsp;
40

>img width="100px" height="25px" src="ValidateImageHandler.ashx"/<

>/ td <
41 >/ tr <
42 > tr <
43 > td align = " left " colspan = " 2 " style = " color: red " <
44 > asp:CheckBox ID = " RememberMe " runat = " server " Text = " 下次记住我。 " /<& nbsp; >/ td <
45 >/ tr <
46 > tr <
47 > td align = " right " colspan = " 2 " <
48 > asp:Button ID = " LoginButton " runat = " server " BackColor = " White " BorderColor = " #507CD1 "
49 BorderStyle = " Solid " BorderWidth = " 1px " CommandName = " Login " Font - Names = " Verdana "
50 Font - Size = " 0.8em " ForeColor = " #284E98 " Text = " 登录 " ValidationGroup = " Login1 " /<
51 >/ td <
52 >/ tr <
53 >/ table <
54 >/ td <
55 >/ tr <
56 >/ table <
57 >/ LayoutTemplate <
58
59 >/ asp:Login <
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 > httpHandlers <
2 > add verb = " * " path = " *.asah " type = " System.Web.UI.SimpleHandlerFactory " /<
3 >/ httpHandlers <
4

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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