3个随机图片验证代码

 

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Drawing.Design;
using System.Drawing;
using System.Text;

namespace Webform
{
    public partial class imgCheck : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            this.CreateCheckCodeImage(RndNumcn2());

        }

        //随机字母的简单算法
        private string RndNum()
        {
            int number;
            char code;
            string checkCode = String.Empty;

            System.Random random = new Random();

            for (int i = 0; i < 4; i++)
            {
                number = random.Next();
                if (number % 2 == 0)
                    code = (char)('0' + (char)(number % 10));
                else
                    code = (char)('A' + (char)(number % 26));
                checkCode += code.ToString();
            }
            Response.Cookies.Add(new HttpCookie("checkCode", checkCode));
            return checkCode;
        }

        //简单的随机汉字算法
        private string RndNumcn()
        {
            string letters = "我爱你猪宝贝";
            string letter;
            string checkCode = "";

            System.Random r = new Random();

            for (int x = 0; x < 2; x++)
            {
                letter = letters.Substring(r.Next(0, letters.Length - 1), 1);
                checkCode += letter;
            }
            Response.Cookies.Add(new HttpCookie("checkCode", checkCode));
            return checkCode;

        }

        //复杂随机汉字算法
        private string RndNumcn2()
        {
            Encoding gb = Encoding.GetEncoding("gb2312");

            //调用函数产生4个随机中文汉字编码
            object[] bytes = CreateRegionCode(4);

            //根据汉字编码的字节数组解码出中文汉字
            string str1 = gb.GetString((byte[])Convert.ChangeType(bytes[0], typeof(byte[])));
            string str2 = gb.GetString((byte[])Convert.ChangeType(bytes[1], typeof(byte[])));
            string str3 = gb.GetString((byte[])Convert.ChangeType(bytes[2], typeof(byte[])));
            string str4 = gb.GetString((byte[])Convert.ChangeType(bytes[3], typeof(byte[])));

            string checkCode= (str1 + str2 + str3 + str4);
            Response.Cookies.Add(new HttpCookie("checkCode", checkCode));
            return checkCode;
        }

 

        public static object[] CreateRegionCode(int strlength)
        {
            //定义一个字符串数组储存汉字编码的组成元素
            string[] rBase=new String [16]{"0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f"};
            
            Random rnd=new Random();
        
            //定义一个object数组用来
            object[] bytes=new object[strlength];
 
            /**//*每循环一次产生一个含两个元素的十六进制字节数组，并将其放入bject数组中
             每个汉字有四个区位码组成
             区位码第1位和区位码第2位作为字节数组第一个元素
             区位码第3位和区位码第4位作为字节数组第二个元素
            */
            for(int i=0;i<strlength;i++)
            {
                //区位码第1位
                int r1=rnd.Next(11,14);
                string str_r1=rBase[r1].Trim();
 
                //区位码第2位
                rnd=new Random(r1*unchecked((int)DateTime.Now.Ticks)+i);//更换随机数发生器的种子避免产生重复值
                int r2;
                if (r1==13)
                {
                    r2=rnd.Next(0,7);
                }
                else
                {
                    r2=rnd.Next(0,16);
                }
                string str_r2=rBase[r2].Trim();
 
                //区位码第3位
                rnd=new Random(r2*unchecked((int)DateTime.Now.Ticks)+i);
                int r3=rnd.Next(10,16);
                string str_r3=rBase[r3].Trim();
 
                //区位码第4位
                rnd=new Random(r3*unchecked((int)DateTime.Now.Ticks)+i);
                int r4;
                if (r3==10)
                {
                    r4=rnd.Next(1,16);
                }
                else if (r3==15)
                {
                    r4=rnd.Next(0,15);
                }
                else
                {
                    r4=rnd.Next(0,16);
                }
                string str_r4=rBase[r4].Trim();
 
                //定义两个字节变量存储产生的随机汉字区位码
                byte byte1=Convert.ToByte(str_r1 + str_r2,16);
                byte byte2=Convert.ToByte(str_r3 + str_r4,16);
                //将两个字节变量存储在字节数组中
                byte[] str_r=new byte[]{byte1,byte2};
 
                //将产生的一个汉字的字节数组放入object数组中
                bytes.SetValue(str_r,i);
                
            }
 
            return bytes;
 
            }

        private void CreateCheckCodeImage(string checkCode)
        {

            if (checkCode == null || checkCode.Trim() == String.Empty)
                return;
            System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 22.5)), 22);
            Graphics g = Graphics.FromImage(image);
            try
            {
                //生成随机生成器
                Random random = new Random();
                //清空图片背景色
                g.Clear(Color.White);
                //画图片的背景噪音线
                for (int i = 0; i < 8; i++)
                {
                    int x1 = random.Next(image.Width);
                    int x2 = random.Next(image.Width);
                    int y1 = random.Next(image.Height);
                    int y2 = random.Next(image.Height);
                    g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
                }

                Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));
                System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);
                g.DrawString(checkCode, font, brush, 2, 2);
                //画图片的前景噪音点
                for (int i = 0; i < 10; i++)
                {
                    int x = random.Next(image.Width);
                    int y = random.Next(image.Height);
                    image.SetPixel(x, y, Color.FromArgb(random.Next()));
                }
                //画图片的边框线
                g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
                System.IO.MemoryStream ms = new System.IO.MemoryStream();
                image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
                Response.ClearContent();
                Response.ContentType = "image/Gif";
                Response.BinaryWrite(ms.ToArray());
            }
            finally
            {
                g.Dispose();
                image.Dispose();
            }
        }

   

    }
}

 

 

 

客户端测试：

    <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
    <div>
    <asp:ImageButton ID="yzm" runat="server" ImageUrl="imgcheck.aspx" />
<asp:LinkButton ID="ChangeCode" runat="server" Text="看不清楚？换一个验证码"  />
        <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Button" /></div>

 

 

            if (String.Compare(Request.Cookies["checkCode"].Value, TextBox1.Text, true) != 0)
            {
                Response.Write("<script>alert('验证码错误!')</script>");
            }
            else
            {
                Response.Write("<script>alert('验证吗正确!!!')</script>");
            }