由12306动态验证码想到的ASP.NET实现动态GIF验证码(附源码)

 public void ShowCode()        {            //对象实例化            Validate GifValidate = new Validate();            #region 对验证码进行设置(不进行设置时,将以默认值生成)            //验证码位数，不小于4位            GifValidate.ValidateCodeCount = 4;            //验证码字体型号(默认13)            GifValidate.ValidateCodeSize = 13;            //验证码图片高度,高度越大,字符的上下偏移量就越明显            GifValidate.ImageHeight = 23;            //验证码字符及线条颜色(需要参考颜色类)            GifValidate.DrawColor = System.Drawing.Color.BlueViolet;            //验证码字体(需要填写服务器安装的字体)            GifValidate.ValidateCodeFont = "Arial";            //验证码字符是否消除锯齿            GifValidate.FontTextRenderingHint = false;            //定义验证码中所有的字符(","分离),似乎暂时不支持中文            GifValidate.AllChar = "1,2,3,4,5,6,7,8,9,0,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,W,X,Y,Z";            #endregion            //输出图像(Session名称)            GifValidate.OutPutValidate("GetCode");        }

public class Validate    {        public string AllChar = "1,2,3,4,5,6,7,8,9,0,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,W,X,Y,Z";        public Color DrawColor = Color.BlueViolet;        public bool FontTextRenderingHint = false;        public int ImageHeight = 0x17;        private byte TrueValidateCodeCount = 4;        protected string ValidateCode = "";        public string ValidateCodeFont = "Arial";        public float ValidateCodeSize = 13f;        private void CreateImageBmp(out Bitmap ImageFrame)        {            char[] chArray = this.ValidateCode.ToCharArray(0, this.ValidateCodeCount);            int width = (int) (((this.TrueValidateCodeCount * this.ValidateCodeSize) * 1.3) + 4.0);            ImageFrame = new Bitmap(width, this.ImageHeight);            Graphics graphics = Graphics.FromImage(ImageFrame);            graphics.Clear(Color.White);            Font font = new Font(this.ValidateCodeFont, this.ValidateCodeSize, FontStyle.Bold);            Brush brush = new SolidBrush(this.DrawColor);            int maxValue = (int) Math.Max((float) ((this.ImageHeight - this.ValidateCodeSize) - 3f), (float) 2f);            Random random = new Random();            for (int i = 0; i < this.TrueValidateCodeCount; i++)            {                int[] numArray = new int[] { (((int) (i * this.ValidateCodeSize)) + random.Next(1)) + 3, random.Next(maxValue) };                Point point = new Point(numArray[0], numArray[1]);                if (this.FontTextRenderingHint)                {                    graphics.TextRenderingHint = TextRenderingHint.SingleBitPerPixel;                }                else                {                    graphics.TextRenderingHint = TextRenderingHint.AntiAlias;                }                graphics.DrawString(chArray[i].ToString(), font, brush, (PointF) point);            }            graphics.Dispose();        }        private void CreateImageGif()        {            AnimatedGifEncoder encoder = new AnimatedGifEncoder();            MemoryStream stream = new MemoryStream();            encoder.Start();            encoder.SetDelay(5);            encoder.SetRepeat(0);            for (int i = 0; i < 10; i++)            {                Bitmap bitmap;                this.CreateImageBmp(out bitmap);                this.DisposeImageBmp(ref bitmap);                bitmap.Save(stream, ImageFormat.Png);                encoder.AddFrame(Image.FromStream(stream));                stream = new MemoryStream();            }            encoder.OutPut(ref stream);            HttpContext.Current.Response.ClearContent();            HttpContext.Current.Response.ContentType = "image/Gif";            HttpContext.Current.Response.BinaryWrite(stream.ToArray());            stream.Close();            stream.Dispose();        }        private void CreateValidate()        {            this.ValidateCode = "";            string[] strArray = this.AllChar.Split(new char[] { ',' });            int index = -1;            Random random = new Random();            for (int i = 0; i < this.ValidateCodeCount; i++)            {                if (index != -1)                {                    random = new Random((i * index) * ((int) DateTime.Now.Ticks));                }                int num3 = random.Next(0x23);                if (index == num3)                {                    this.CreateValidate();                }                index = num3;                this.ValidateCode = this.ValidateCode + strArray[index];            }            if (this.ValidateCode.Length > this.TrueValidateCodeCount)            {                this.ValidateCode = this.ValidateCode.Remove(this.TrueValidateCodeCount);            }        }        private void DisposeImageBmp(ref Bitmap ImageFrame)        {            Graphics graphics = Graphics.FromImage(ImageFrame);            Pen pen = new Pen(this.DrawColor, 1f);            Random random = new Random();            Point[] pointArray = new Point[2];            for (int i = 0; i < 15; i++)            {                pointArray[0] = new Point(random.Next(ImageFrame.Width), random.Next(ImageFrame.Height));                pointArray[1] = new Point(random.Next(ImageFrame.Width), random.Next(ImageFrame.Height));                graphics.DrawLine(pen, pointArray[0], pointArray[1]);            }            graphics.Dispose();        }        public void OutPutValidate(string ValidateCodeSession)        {            this.CreateValidate();            this.CreateImageGif();            HttpContext.Current.Session[ValidateCodeSession] = this.ValidateCode;        }        public byte ValidateCodeCount        {            get            {                return this.TrueValidateCodeCount;            }            set            {                if (value > 4)                {                    this.TrueValidateCodeCount = value;                }            }        }    }