asp.net|示例|下载|验证码学习整理了一下(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 &n, bsp; <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 <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。" /> </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.
