本文实例讲述了WinForm生成验证码图片的方法。分享给大家供大家参考，具体如下：

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());

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