public class ValidCode{#region Private Fieldsprivate 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 Propertypublic 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 Fieldpublic enum CodeType { Words, Numbers, Characters, Alphas }#endregion#region Private Methodsprivate 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 Methodspublic 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}