C# winform登陆框验证码的实现

验证码技术已愈来愈成熟，从最初的数字、字母、字符、汉字已经到目前的语言，其应用也甚广，之前大多数只有在网站上可以看到，现在在一些客户端软件也经常可见（比如证券相关软件）。之前做的一个基于 C# 客户端连 J2EE 应用的项目，其 Login Form 也要求实现验证码，在此贴上。

1、 新建一个简单的 windows 应用项目
在默认的 Form1 中添加如下控件：
1） Label ： text = “ 输入验证码 :”
2） TextBox ： name=” txtValidCode” 输入验证码的文本框
3） Image ： name=” picValidCode” 显示验证码的图片控件
4） Button ：单击事件进行验证码验证

2、 新建一个产生验证码的核心类，并构建其一个实例： ValidCode validCode = new ValidCode (5, ValidCode .CodeType .Numbers)

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 } }

3、 图片加载验证码、验证码验证
// 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 ;
}