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 <% @ 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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