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      &