webform 图片验证码制作

 界面：
1 <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default2.aspx.cs" Inherits="Default2" %>
 2 
 3 <!DOCTYPE html>
 4 
 5 <html xmlns="http://www.w3.org/1999/xhtml">
 6 <head runat="server">
 7     <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
 8     <title></title>
 9 </head>
10 <body>
11     <form id="form1" runat="server">
12         <div>
13             <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
14             <asp:Image ID="Image1" runat="server" ImageUrl="YZM.aspx" />
15             <asp:Button ID="Button1" runat="server" Text="验证" />
16             <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
17         </div>
18     </form>
19 </body>
20 </html>
21 <script type="text/javascript">
22     var a = 0;
23     //点击图片更换验证码
24     document.getElementById("Image1").onclick = function () {
25         this.setAttribute("src", "yzm.aspx?id=" + a);
26         a++;
27     }
28 </script>

后台：

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Web;
 5 using System.Web.UI;
 6 using System.Web.UI.WebControls;
 7 
 8 public partial class Default2 : System.Web.UI.Page
 9 {
10     protected void Page_Load(object sender, EventArgs e)
11     {
12         Button1.Click += Button1_Click;
13     }
14 
15     void Button1_Click(object sender, EventArgs e)
16     {
17         string t1 = TextBox1.Text;
18         string t2 = Session["YZM"].ToString();
19 
20         if (t1.ToUpper() == t2.ToUpper())
21         {
22             Label1.Text = "验证成功！";
23         }
24         else
25         {
26             Label1.Text = "验证失败！";
27         }
28 
29 
30     }
31 }

验证码制作：

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Web;
 5 using System.Web.UI;
 6 using System.Web.UI.WebControls;
 7 using System.Drawing;
 8 
 9 public partial class YZM : System.Web.UI.Page
10 {
11     protected void Page_Load(object sender, EventArgs e)
12     {
13         Bitmap img = new Bitmap(80, 40);//验证码图片大小
14         Graphics g = Graphics.FromImage(img);
15         Random r = new Random();
16         //背景色
17         List<Color> clist = new List<Color>();
18         clist.Add(Color.Yellow);
19         clist.Add(Color.Green);
20         clist.Add(Color.Blue);
21         clist.Add(Color.Pink);
22         clist.Add(Color.Orange);
23         clist.Add(Color.AliceBlue);
24         clist.Add(Color.Aqua);
25         clist.Add(Color.Cyan);
26         clist.Add(Color.DarkOliveGreen);
27         clist.Add(Color.Black);
28 
29         g.FillRectangle(new SolidBrush(clist[r.Next(0, clist.Count)]), 0, 0, 80, 40);
30 
31 
32         
33         for (int i = 0; i < 10; i++)
34         {
35             Color ccc = clist[r.Next(0, clist.Count)];//随机颜色
36 
37             Pen ppp = new Pen(new SolidBrush(ccc), r.Next(1, 5));//随机线条
38 
39             g.DrawLine(ppp, new PointF(r.Next(0, 80), r.Next(0, 40)), new PointF(r.Next(0, 80), r.Next(0, 40)));
40         }
41 
42 
43 
44 
45         //验证码
46         string all = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
47         string s = "";
48 
49         for (int i = 0; i < 4; i++)
50         {
51             int a = r.Next(all.Length);//随机取数
52             s += all.Substring(a, 1);
53         }
54 
55         Session["YZM"] = s;
56 
57         g.DrawString(s, new Font("微软雅黑", 16), new SolidBrush(Color.Red), new PointF(3, 3));
58 
59         img.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Png);
60         Response.End();
61 
62     }
63 }