由12306动态验证码想到的ASP.NET实现动态GIF验证码(附源码)

背景：

12306网站推出“彩色动态验证码机制”，新版验证码不但经常出现字符叠压，还不停抖动，不少人大呼“看不清”，称“那个验证码，是毕加索的抽象画么!”铁总客服则表示:为了能正常购票只能这样。而多家抢票软件接近“报废”，引发不少网友不满的吐槽称“太抽象太艺术了”。

正题：

以前做项目有时候也会用到验证码，但基本都是静态的。这次也想凑凑12306的热闹。

闲言少续，切入正题，先上代码，实现方法：

 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");
        }

调用主要方法：

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;
                }
            }
        }
    }

验证码效果：

 16aspx下载

本地下载