[ASP.NET] 验证码生成

类：

CheckCode.cs
 1//----------------------------------------------------------------------
 2// Ryan Wei
 3// Date:2008.05.08
 4//----------------------------------------------------------------------
 5// Description: 
 6//----------------------------------------------------------------------
 7using System;
 8using System.Collections.Generic;
 9using System.Text;
10using System.Drawing;
11
12namespace HouseProgram.Common
13{
14    public class CheckCode
15    {
16        /**///// <summary>
17        /// 生成随机数
18        /// </summary>
19        /// <param name="codeCount">要生成的随机数位数</param>
20        /// <returns></returns>
21        public static string CreateRandomCode(int codeCount)
22        {
23            string allChar = "0,1,2,3,4,5,6,7,8,9";
24            string[] allCharArray = allChar.Split(',');
25            string randomCode = "";
26            int temp = -1;
27
28            Random rand = new Random();
29            for(int i = 0; i < codeCount; i++)
30            {
31                if(temp != -1)
32                {
33                    rand = new Random(i*temp*((int)DateTime.Now.Ticks));
34                }
35                int t = rand.Next(9);
36                if(temp == t)
37                {
38                    return CreateRandomCode(codeCount);
39                }
40                temp = t;
41                randomCode += allCharArray[t];
42            }
43            return randomCode;
44        }
45        /**///// <summary>
46        /// 生成验证码图片
47        /// </summary>
48        /// <param name="checkCode"></param>
49        public static void CreateImage(string checkCode)
50        {
51            int iwidth = (int)(checkCode.Length * 11.5);
52            System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 20);
53            Graphics g = Graphics.FromImage(image);
54            Font f = new System.Drawing.Font("Arial", 10, System.Drawing.FontStyle.Bold);
55            Brush b = new System.Drawing.SolidBrush(Color.White);
56            g.Clear(Color.Blue);
57            g.DrawString(checkCode, f, b, 3, 3);
58
59            Pen blackPen = new Pen(Color.Brown,0);
60            Random rand = new Random();
61            for (int i=0;i<5;i++)
62            {
63                int y = rand.Next(image.Height);
64            }
65            
66            System.IO.MemoryStream ms = new System.IO.MemoryStream();
67            for(int i=0; i<90; i++)
68            {
69                int x = rand.Next(image.Width);
70                int y = rand.Next(image.Height);
71                image.SetPixel(x, y, Color.FromArgb(rand.Next()));
72            }
73            image.Save(ms,System.Drawing.Imaging.ImageFormat.Jpeg);
74            System.Web.HttpContext.Current.Response.ClearContent();
75            System.Web.HttpContext.Current.Response.ContentType = "image/Jpeg";
76            System.Web.HttpContext.Current.Response.BinaryWrite(ms.ToArray());
77            g.Dispose();
78            image.Dispose();
79        }
80    }
81}
82

页面后台代码：

checkCode.aspx.cs
 1//----------------------------------------------------------------------
 2// Ryan Wei
 3// Date:2008.05.08
 4//----------------------------------------------------------------------
 5// Description: CheckCode Display Page
 6//----------------------------------------------------------------------
 7using System;
 8using System.Data;
 9using System.Configuration;
10using System.Collections;
11using System.Web;
12using System.Web.Security;
13using System.Web.UI;
14using System.Web.UI.WebControls;
15using System.Web.UI.WebControls.WebParts;
16using System.Web.UI.HtmlControls;
17using HouseProgram.Common;
18
19public partial class checkCode : System.Web.UI.Page
20{
21    /**//// <summary>
22    /// 
23    /// </summary>
24    /// <param name="sender"></param>
25    /// <param name="e"></param>
26    protected void Page_Load(object sender, EventArgs e)
27    {
28        //Generate 4 bit CheckCode
29        string checkCode = CheckCode.CreateRandomCode(4);
30        //Cache CheckCode
31        Session[PublicConstString.session_CheckCode] = checkCode;
32        //Create Image
33        CheckCode.CreateImage(checkCode);
34    }
35}
36

在登录页面添加ImageButton,  ImageURL指定为CheckCode.aspx页面。