Winform中产生验证码图片

1、创建ValidCode类：

public class ValidCode
    {

        #region Private Fields

        private const double PI = 3.1415926535897932384626433832795;

        private const double PI2 = 6.283185307179586476925286766559;

        //private readonly int _wordsLen = 4; 

        private int _len;

        private CodeType _codetype;

        private readonly Single _jianju = (float)18.0;

        private readonly Single _height = (float)24.0;

        private string _checkCode;

        #endregion

        #region Public Property

        public string CheckCode
        {

            get
            {

                return _checkCode;

            }

        }

        #endregion

        #region Constructors

        /// <summary> 

        /// public constructors 

        /// </summary> 

        /// <param name="len"> 验证码长度 </param> 

        /// <param name="ctype"> 验证码类型：字母、数字、字母+ 数字 </param> 

        public ValidCode(int len, CodeType ctype)
        {

            this._len = len;

            this._codetype = ctype;

        }

        #endregion

        #region Public Field

        public enum CodeType { Words, Numbers, Characters, Alphas }

        #endregion

        #region Private Methods

        private string GenerateNumbers()
        {

            string strOut = "";

            System.Random random = new Random();

            for (int i = 0; i < _len; i++)
            {

                string num = Convert.ToString(random.Next(10000) % 10);

                strOut += num;

            }

            return strOut.Trim();

        }

        private string GenerateCharacters()
        {

            string strOut = "";

            System.Random random = new Random();

            for (int i = 0; i < _len; i++)
            {

                string num = Convert.ToString((char)(65 + random.Next(10000) % 26));

                strOut += num;

            }

            return strOut.Trim();

        }

        // 

        private string GenerateAlphas()
        {

            string strOut = "";

            string num = "";

            System.Random random = new Random();

            for (int i = 0; i < _len; i++)
            {

                if (random.Next(500) % 2 == 0)
                {

                    num = Convert.ToString(random.Next(10000) % 10);

                }

                else
                {

                    num = Convert.ToString((char)(65 + random.Next(10000) % 26));

                }

                strOut += num;

            }

            return strOut.Trim();

        }

        private System.Drawing.Bitmap TwistImage(Bitmap srcBmp, bool bXDir, double dMultValue, double dPhase)
        {

            System.Drawing.Bitmap destBmp = new Bitmap(srcBmp.Width, srcBmp.Height);

            // 将位图背景填充为白色 

            System.Drawing.Graphics graph = System.Drawing.Graphics.FromImage(destBmp);

            graph.FillRectangle(new SolidBrush(System.Drawing.Color.White), 0, 0, destBmp.Width, destBmp.Height);

            graph.Dispose();

            double dBaseAxisLen = bXDir ? (double)destBmp.Height : (double)destBmp.Width;

            for (int i = 0; i < destBmp.Width; i++)
            {

                for (int j = 0; j < destBmp.Height; j++)
                {

                    double dx = 0;

                    dx = bXDir ? (PI2 * (double)j) / dBaseAxisLen : (PI2 * (double)i) / dBaseAxisLen;

                    dx += dPhase;

                    double dy = Math.Sin(dx);

                    // 取得当前点的颜色 

                    int nOldX = 0, nOldY = 0;

                    nOldX = bXDir ? i + (int)(dy * dMultValue) : i;

                    nOldY = bXDir ? j : j + (int)(dy * dMultValue);

                    System.Drawing.Color color = srcBmp.GetPixel(i, j);

                    if (nOldX >= 0 && nOldX < destBmp.Width

                     && nOldY >= 0 && nOldY < destBmp.Height)
                    {

                        destBmp.SetPixel(nOldX, nOldY, color);

                    }

                }

            }

            return destBmp;

        }

        #endregion

        #region Public Methods

        public Stream CreateCheckCodeImage()
        {

            string checkCode;

            switch (_codetype)
            {

                case CodeType.Alphas:

                    checkCode = GenerateAlphas();

                    break;

                case CodeType.Numbers:

                    checkCode = GenerateNumbers();

                    break;

                case CodeType.Characters:

                    checkCode = GenerateCharacters();

                    break;

                default:

                    checkCode = GenerateAlphas();

                    break;

            }

            this._checkCode = checkCode;

            MemoryStream ms = null;

            // 

            if (checkCode == null || checkCode.Trim() == String.Empty)

                return null;

            Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * _jianju)), (int)_height);

            Graphics g = Graphics.FromImage(image);

            try
            {

                Random random = new Random();

                g.Clear(Color.White);

                // 画图片的背景噪音线 

                for (int i = 0; i < 18; i++)
                {

                    int x1 = random.Next(image.Width);

                    int x2 = random.Next(image.Width);

                    int y1 = random.Next(image.Height);

                    int y2 = random.Next(image.Height);

                    g.DrawLine(new Pen(Color.FromArgb(random.Next()), 1), x1, y1, x2, y2);

                }

                Font font = new System.Drawing.Font("Times New Roman", 14, System.Drawing.FontStyle.Bold);

                LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);

                if (_codetype != CodeType.Words)
                {

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

                        g.DrawString(checkCode.Substring(i, 1), font, brush, 2 + i * _jianju, 1);

                    }

                }
                else
                {

                    g.DrawString(checkCode, font, brush, 2, 2);

                }

                // 画图片的前景噪音点 

                for (int i = 0; i < 150; i++)
                {

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

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

                    image.SetPixel(x, y, Color.FromArgb(random.Next()));

                }

                // 画图片的波形滤镜效果 

                if (_codetype != CodeType.Words)
                {

                    image = TwistImage(image, true, 3, 1);

                }

                // 画图片的边框线 

                g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);

                ms = new System.IO.MemoryStream();

                image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);

            }

            finally
            {

                g.Dispose();

                image.Dispose();

            }

            return ms;

        }

        #endregion

    }

2、产生验证码图片代码：

//参数一：产生几个字符的验证码图片  参数二：验证码的形式(数字、字母、数字字母混合都有)
ValidCode validCode = new ValidCode(5, ValidCode.CodeType.Alphas);

this.pictureBox2.Image = Bitmap.FromStream(validCode.CreateCheckCodeImage());