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

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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> 
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" />