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 ///

11 /// ValidateImageHandler 生成网站验证码功能
12 ///

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      ///

22 /// 生成验证图片核心代码
23 ///

24      ///
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      ///

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 ///

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> 
40

                                        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。" />  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