生成图片验证码类

using System;

using System.IO;

using System.Web;

using System.Text;

using System.Drawing;

using System.Drawing.Imaging;

/// <summary>

///Cls_PicVcode生成图片

/// </summary>

public class ValidateCode

{

    /// <summary>

    /// 该方法用于生成指定位数的随机数

    /// </summary>

    /// <param name="VcodeNum">参数是随机数的位数</param>

    /// <returns>返回一个随机数字符串</returns>

    private string RndNum(int VcodeNum)

    {

        string Vchar = "1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,L,M,N,P" +

            ",Q,R,S,T,U,V,W,X,Y,Z";

        string[] VcArray = Vchar.Split(new Char[] { '','' });//拆分成数组

        string VNum = "";//产生的随机数

        int temp = -1;//记录上次随机数值，尽量避免生产几个一样的随机数

        Random rand = new Random();

        for (int i = 1; i < VcodeNum + 1; i++)

        {

            if (temp != -1)

            {

                rand = new Random(i * temp * unchecked((int)DateTime.Now.Ticks));

            }

            int t = rand.Next(33);

            if (temp != -1 && temp == t)

            {

                return RndNum(VcodeNum);

            }

            temp = t;

            VNum += VcArray[t];

        }

        return VNum;

    }

    /// <summary>

    /// 该方法是将生成的随机数写入图像文件

    /// </summary>

    /// <param name="VNum">VNum是一个随机数</param>

    public MemoryStream Create(out string VNum)

    {

        VNum = RndNum(4);

        Bitmap Img = null;

        Graphics g = null;

        MemoryStream ms = null;

        System.Random random = new Random();

        //验证码颜色集合

        Color[] c = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple };

        //验证码字体集合

        string[] fonts = { "Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", "宋体" };





        //定义图像的大小，生成图像的实例

        Img = new Bitmap(100, 25);



        g = Graphics.FromImage(Img);//从Img对象生成新的Graphics对象 



        g.Clear(Color.White);//背景设为白色



        //在随机位置画背景点

        for (int i = 0; i < 100; i++)

        {

            int x = random.Next(Img.Width);

            int y = random.Next(Img.Height);

            g.DrawRectangle(new Pen(Color.LightGray, 0), x, y, 1, 1);

        }

        //验证码绘制在g中

        for (int i = 0; i < VNum.Length; i++)

        {

            int cindex = random.Next(7);//随机颜色索引值

            int findex = random.Next(5);//随机字体索引值

            Font f = new System.Drawing.Font(fonts[findex], 14, System.Drawing.FontStyle.Bold);//字体

            Brush b = new System.Drawing.SolidBrush(c[cindex]);//颜色

            int ii = 4;

            if ((i + 1) % 2 == 0)//控制验证码不在同一高度

            {

                ii = 2;

            }

            g.DrawString(VNum.Substring(i, 1), f, b, 3 + (i * 20), ii);//绘制一个验证字符

        }

        ms = new MemoryStream();//生成内存流对象

        Img.Save(ms, ImageFormat.Jpeg);//将此图像以jpg图像文件的格式保存到流中



        //回收资源

        g.Dispose();

        Img.Dispose();

        return ms;



    }

}