验证码生成类

public class ValidatorCode : IHttpHandler, IRequiresSessionState
    {
        public void ProcessRequest(HttpContext Context)
        {
            //定义图片的宽度
            int ImageWidth = 57;
            //定义图片高度
            int ImageHeigh = 21;
            //定义字体，用于绘制文字
            Font font = new Font("Arial", 12, FontStyle.Bold);
            //定义画笔，用于绘制文字
            Brush brush = new SolidBrush(Color.Black);
            //定义钢笔，用于绘制干扰线
            Pen pen1 = new Pen(Color.FromArgb(255, 100, 100), 0);//这里也可以直接获得一个现有的color对象如：Color.Gold.我是为了美观所以定义和下面一样
            Pen pen2 = new Pen(Color.FromArgb(255, 100, 100), 0);//这里根据ARGB值定义获得了一个color对象
            //创建一个图像
            Bitmap BitImage = new Bitmap(ImageWidth, ImageHeigh);
            //从图像获取一个绘画面
            Graphics graphics = Graphics.FromImage(BitImage);
            //清除整个绘图画面并用颜色填充
            graphics.Clear(ColorTranslator.FromHtml("#F0F0F0"));//这里从HTML代码获取color对象
            //定义文字的绘制矩形区域
            RectangleF rect = new RectangleF(5, 2, ImageWidth, ImageHeigh);
            //定义一个随机数对象，用于绘制干扰线
            Random rand = new Random();
            //生成两条横向的干扰线
            for (int i = 0; i < 2; i++)
            {
                //定义起点
                Point p1 = new Point(0, rand.Next(ImageHeigh));
                //定义终点
                Point p2 = new Point(ImageWidth, rand.Next(ImageHeigh));
                //绘制直线
                graphics.DrawLine(pen1, p1, p2);
            }
            //生成两条纵向的干扰线
            for (int i = 0; i < 2; i++)
            {
                //定义起点
                Point p1 = new Point(rand.Next(ImageWidth), 0);
                //定义终点
                Point p2 = new Point(rand.Next(ImageWidth), ImageHeigh);
                //绘制直线
                graphics.DrawLine(pen2, p1, p2);
            }
            //绘制验证码文字
            //GetSession.Add("LoginCode", this.RndNum().ToUpper(), 5);
            //将验证码写入Cookies
            Cookies.Add("LoginCode", this.RndNum().ToUpper(), DateTime.Now.AddMinutes(5));
            graphics.DrawString(this.RndNum(), font, brush, rect);
            Context.Response.Clear();
            Context.Response.ContentType = "image/jpeg";
            //保存图片为gif格式
            BitImage.Save(Context.Response.OutputStream, ImageFormat.Jpeg);
            //释放对象
            BitImage.Dispose();
            graphics.Dispose();
        }
        /// <summary>
        /// 产生一个4位数的随机字符串
        /// </summary>
        /// <returns></returns>
        private string RndNum()
        {
            //定义用于验证码的字符数组
            char[] AllCheckCodeArray ={ '0','1','2','3','4','5','6','7','8','9','a','b','c',
        'd','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w',
        'x','y','z','A','B','C','D','E','F','G','H','J','K','L','M','N','P','Q','R','S','T','U','W','V','X','Y','Z'};
            //定义验证码字符串
            StringBuilder randomcode = new StringBuilder();
            Random rd = new Random();
            //生成4位验证码字符串
            for (int i = 0; i < 4; i++)
            {
                randomcode.Append(AllCheckCodeArray[rd.Next(AllCheckCodeArray.Length)]);
            }
            return randomcode.ToString();
        }
        /// <summary>
        /// 是否可以重复使用
        /// </summary>
        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }