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

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 <% @WebHandlerLanguage = " 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 /// <paramname="hc"></param>
25 public void ProcessRequest(HttpContexthc)
26 {
27 // 设置输出流图片格式
28 hc.Response.ContentType = " image/gif " ;
29
30 Bitmapb = new Bitmap( 200 , 60 );
31 Graphicsg = Graphics.FromImage(b);
32 g.FillRectangle( new SolidBrush(Color.YellowGreen), 0 , 0 , 200 , 60 );
33 Fontfont = new Font(FontFamily.GenericSerif, 48 ,FontStyle.Bold,GraphicsUnit.Pixel);
34 Randomr = new Random();
35
36 // 合法随机显示字符列表
37 string strLetters = " abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890 " ;
38 StringBuilders = 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 Penpen = 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:LoginID = " 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 < TitleTextStyleBackColor = " #507CD1 " Font - Bold = " True " Font - Size = " 0.9em " ForeColor = " White " />
3 < InstructionTextStyleFont - Italic = " True " ForeColor = " Black " />
4 < TextBoxStyleFont - Size = " 0.8em " />
5 < LoginButtonStyleBackColor = " White " BorderColor = " #507CD1 " BorderStyle = " Solid " BorderWidth = " 1px "
6 Font - Names = " Verdana " Font - Size = " 0.8em " ForeColor = " #284E98 " />
7 < LayoutTemplate >
8 < tableborder = " 0 " cellpadding = " 4 " cellspacing = " 0 " style = " border-collapse:collapse " >
9 < tr >
10 < tdstyle = " width:292px " >
11 < tableborder = " 0 " cellpadding = " 0 " >
12 < tr >
13 < tdalign = " 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 < tdalign = " left " style = " width:84px;height:31px; " >
19 < asp:LabelID = " UserNameLabel " runat = " server " AssociatedControlID = " UserName " > 用户名: </ asp:Label ></ td >
20 < tdstyle = " height:31px;width:215px; " >
21 < asp:TextBoxID = " UserName " runat = " server " Font - Size = " 0.8em " Width = " 113px " ></ asp:TextBox >
22 < asp:RequiredFieldValidatorID = " 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 < tdalign = " left " style = " width:84px " >
28 < asp:LabelID = " PasswordLabel " runat = " server " AssociatedControlID = " Password " > 密码: </ asp:Label ></ td >
29 < tdstyle = " width:215px " >
30 < asp:TextBoxID = " Password " runat = " server " Font - Size = " 0.8em " TextMode = " Password " ></ asp:TextBox >
31 < asp:RequiredFieldValidatorID = " 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 < tdstyle = " width:84px;height:4px; " align = " left " >
37 验证码: </ td >
38 < tdvalign = " middle " style = " height:31px;width:215px; " align = " left " >
39 < asp:TextBoxID = " TextBox1 " runat = " server " Font - Size = " 0.8em " TextMode = " Password " ></ asp:TextBox >& nbsp;
40

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

</ td >
41 </ tr >
42 < tr >
43 < tdalign = " left " colspan = " 2 " style = " color:red " >
44 < asp:CheckBoxID = " RememberMe " runat = " server " Text = " 下次记住我。 " />& nbsp; </ td >
45 </ tr >
46 < tr >
47 < tdalign = " right " colspan = " 2 " >
48 < asp:ButtonID = " 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 < addverb = " * " 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