/// <summary>    /// 图形验证码类    /// </summary>    public class PicCaptcha    {        #region Constructed Methods        /// <summary>        /// 默认构造方法        /// </summary>        public PicCaptcha()        {        }        /// <summary>        ///构造方法         /// </summary>        /// <param name="cpatchaType">验证码类型</param>        public PicCaptcha(CaptchaType cpatchaType)        {            this.CaptchaType = cpatchaType;        }        /// <summary>        /// 构造方法        /// </summary>        /// <param name="captchaType">验证码类型</param>        /// <param name="width">图形宽度</param>        /// <param name="height">图形高度</param>        public PicCaptcha(CaptchaType captchaType, int width, int height)            : this(captchaType)        {            this.Width = width;            this.Height = height;        }        /// <summary>        /// 构造方法        /// </summary>        /// <param name="captchaType">验证码类型</param>        /// <param name="width">图形宽度</param>        /// <param name="height">图形高度</param>        /// <param name="fontSize">字体大小</param>        public PicCaptcha(CaptchaType captchaType, int width, int height, int fontSize)            : this(captchaType, width, height)        {            this.FontSize = fontSize;        }        #endregion        #region Fields        private int _width = 80;                                    //default width        private int _height = 25;                                   //default height        private int _fontSize = 16;                                 //default fontSize        private CaptchaType _captchaType = CaptchaType.RandomType;  //default captchaType        #endregion        #region Properties        /// <summary>        /// 验证码图形宽度        /// </summary>        public int Width        {            get { return _width; }            set { _width = value; }        }        /// <summary>        /// 验证码图形高度        /// </summary>        public int Height        {            get { return _height; }            set { _height = value; }        }        /// <summary>        /// 验证码字体大小        /// </summary>        public int FontSize        {            get { return _fontSize; }            set { _fontSize = value; }        }        /// <summary>        /// 验证码类型        /// </summary>        public CaptchaType CaptchaType        {            get { return _captchaType; }            set { _captchaType = value; }        }        #endregion        #region Public Methods        /// <summary>        /// 获取生成的验证码图片        /// </summary>        /// <param name="matchCode">与验证码图片相匹配的内容,一般将该内容保存至session中,用于校验</param>        /// <returns>验证码图片</returns>        public Bitmap GetCaptchaPic(out string matchCode)        {            matchCode = null;            string captchaContent = null;            switch (_captchaType)  //需要生成的验证码类型            {                case CaptchaType.RandomString:                    {                        string randomStr = CreateCheckCodeString(4);                        captchaContent = randomStr;                        matchCode = randomStr;                        break;                    }                case CaptchaType.RandomOperationExpression:                    {                        string[] codes = CreateOperateCheckCode();                        captchaContent = codes[0];                        matchCode = codes[1];                        break;                    }                case CaptchaType.RandomType:                    {                        RandomSelectCreateMethod(out captchaContent, out matchCode);                        break;                    }                default:                    throw new Exception("unknow CaptchaType!");            }            return GenerateCaptchaPic(captchaContent);   //生成验证码图片        }        #endregion        #region  Private Methods        /// <summary>        /// 生成验证码图片        /// </summary>        /// <param name="captchaContent">验证码内容</param>        /// <returns>图片</returns>        private Bitmap GenerateCaptchaPic(string captchaContent)        {            var font = new Font("Arial", _fontSize, FontStyle.Bold);//验证码字体            var brush = new SolidBrush(Color.Black);//用于写验证码的画笔            var crosswise = new Pen(Color.Green, 0);//画横向干扰线的钢笔            var vertical = new Pen(Color.FromArgb(255, 100, 100, 100), 0);//画纵向干扰线的钢笔            var image = new Bitmap(_width, _height);//生成图像            using (Graphics g = Graphics.FromImage(image))  //生成一个绘画面板（画布）            {                g.Clear(ColorTranslator.FromHtml("#f0f0f0"));//用指定颜色填充画布                RectangleF rect = new RectangleF(5, 2, _width, _height);//定义文字的绘制矩形                Random rand = new Random((int)DateTime.Now.Ticks);//生成干扰线的随机对象                for (int i = 1; i <= 4; i++)   //干扰线                {                    Point start = new Point(0, rand.Next(_height));                    Point end = new Point(_width, rand.Next(_height));                    g.DrawLine(crosswise, start, end);                }                for (int i = 1; i <= 5; i++)  //干扰线                {                    Point start = new Point(rand.Next(_width), 0);                    Point end = new Point(rand.Next(_width), _height);                    g.DrawLine(vertical, start, end);                }                g.DrawString(captchaContent, font, brush, rect);//将验证码写到画布上            }            return image;        }        /// <summary>        /// 随机选择生成验证码的方法        /// </summary>        /// <param name="captchaContent">验证码图片显示的内容</param>        /// <param name="matchCode">与验证码图片匹配的内容</param>        private void RandomSelectCreateMethod(out string captchaContent, out string matchCode)        {            captchaContent = "";            matchCode = "";            int currSeconds = DateTime.Now.Second;            if (currSeconds % 2 == 0)            {                captchaContent = matchCode = CreateCheckCodeString(4);            }            else            {                string[] codes = CreateOperateCheckCode();                captchaContent = codes[0];                matchCode = codes[1];            }            return;        }        /// <summary>        /// 生成len位随机字符串        /// </summary>        /// <param name="len">随机字符串长度</param>        /// <returns>len位随机字符串</returns>        private string CreateCheckCodeString(int len)        {            //定义用于验证码的字符数组            char[] checkCodeArray ={ ‘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‘};            //定义验证码字符串            string randomcode = "";            Random rd = new Random();            //生成4位验证码字符串            for (int i = 1; i <= len; i++)                randomcode += checkCodeArray[rd.Next(checkCodeArray.Length)];            return randomcode;        }        /// <summary>        /// 生成随机的运算表达式  1+1=?,2        /// </summary>        /// <returns>codes[0]: 表达式; codes[1]: 运算结果</returns>        private string[] CreateOperateCheckCode()        {            string[] codes = new string[2] { "", "" };            string[] operators = new string[] { "+", "-" };            int result = 0;            Random random = new Random();            int num1 = random.Next(10); // [0,19)            int num2 = random.Next(10);            string oper = operators[random.Next(operators.Length)];            switch (oper)            {                case "+":                    {                        result = num1 + num2;                        break;                    }                case "-":                    {                        result = num1 - num2;                        break;                    }                default:                    throw new Exception("operators error");            }            codes[0] = string.Format("{0}{1}{2}=?", num1, oper, num2);            codes[1] = result.ToString();            return codes;        }        #endregion    }    /// <summary>    /// 生成的验证码类型    /// </summary>    public enum CaptchaType    {        /// <summary>        /// 随机类型, 在所有支持的验证码类型中,随机选择一种        /// </summary>        RandomType,        /// <summary>        /// 普通的随机字符串,如: jH9Y, 12H8        /// </summary>        RandomString,        /// <summary>        /// 随机运算表达式, 如: 1+2=?, 5加2=?, 4-2=?        /// </summary>        RandomOperationExpression,    }

/// <summary>    /// 生成图形验证码    /// </summary>    public class CreateCode : IHttpHandler, IRequiresSessionState    {        private static readonly string CodeSessionName = "Code_Session_Name";        public void ProcessRequest(HttpContext context)        {            string checkCodeSession = string.Empty;             var captChaPic = new PicCaptcha();            using (var image = captChaPic.GetCaptchaPic(out checkCodeSession))  //获取验证码图片            using (var ms = new MemoryStream())            {                context.Session.Add(CodeSessionName, checkCodeSession);         //验证码校验内容保存到sessioin中                image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);                context.Response.ClearContent();                context.Response.ContentType = "image/Gif";                context.Response.BinaryWrite(ms.ToArray());            }            return;        }        public bool IsReusable        {            get            {                return false;            }        }    }