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 ;

  }