C# Winform验证码

建一个产生验证码的核心类

using System; 

using System.Collections.Generic; 

using System.Text; 

using System.IO; 

using System.Drawing; 

using System.Drawing.Drawing2D; 

  

namespace BigHorseLib.Security 

{ 

    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 

    } 

}

ValidCode validCode = new ValidCode (5, ValidCode .CodeType .Numbers)

// 图片加载验证码

picValidCode.Image = Bitmap .FromStream(validCode.CreateCheckCodeImage())

 

// 验证

    if (!this .txtValidCode.Text.Equals(_validCode.CheckCode))

     {

         MessageBox .Show(" 请输入正确的验证码!" , this .Text);

         this .txtValidCode.Focus();

         return ;

  }