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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