验证码

一、造一个验证码的图片

 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 public partial class YZM : System.Web.UI.Page
 9 {
10     protected void Page_Load(object sender, EventArgs e)
11     {
12         //造一个图片
13         Bitmap img = new Bitmap(60, 30);
14         //生成个随机数
15         string str = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";
16         Random rand = new Random();
17         string code = "";
18         for (int i = 0; i < 4; i++)
19         {
20             int start = rand.Next(str.Length);
21             code += str.Substring(start, 1);
22         }
23         Session["yzm"] = code;
24         //把随机数画到图片上
25         SolidBrush brush = new SolidBrush(Color.White);
26         Font font = new Font("Lucida Sans Unicode", 14);
27         Graphics g = Graphics.FromImage(img);
28 
29         //a.把图片背景涂白
30         g.FillRectangle(brush, 0, 0, 60, 30);
31         //b.给画笔换个颜色
32         brush.Color = Color.Red;
33 
34 
35         g.DrawString(code, font, brush, 0, 0);
36 
37         //把图片保存到输出流中去
38         img.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
39 
40         Response.End();
41     }
42 }

造验证码图片

二、建立一个验证的界面并实现

　　　需要控件textbox，image，button

 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 Default5 : System.Web.UI.Page
 9 {
10     protected void Page_Load(object sender, EventArgs e)
11     {
12 
13     }
14     protected void Button1_Click(object sender, EventArgs e)
15     {
16         if (Session["yzm"].ToString() == TextBox1.Text)
17         {
18 
19         }
20     }
21 }

代码

1 <script language="javascript">
2         function changePIC() {
3             var img = document.getElementById("Image1");
4             img.setAttribute("src","yzm.aspx?id="+Math.random());
5         }
6     </script>

js特效换图