[转载]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 = ; i < _len; i++)

            {

                string num = Convert .ToString(random.Next()%);

                strOut += num;

            }

            return strOut.Trim();

        }

        private string GenerateCharacters()

        {

            string strOut = "" ;

            System.Random random = new Random ();

            for (int i = ; i < _len; i++)

            {

                string num = Convert .ToString((char )(+random.Next()%));

                strOut += num;

            }

            return strOut.Trim();

        }

        //

        private string GenerateAlphas()

        {

            string strOut = "" ;

            string num = "" ;

            System.Random random = new Random ();

            for (int i = ; i < _len; i++)

            {

                if (random.Next() %  == )

                {

                    num = Convert .ToString(random.Next() % );

                }

                else

                {

                    num = Convert .ToString((char )( + random.Next() % ));

                }

                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), , , destBmp.Width, destBmp.Height);

            graph.Dispose();

            double dBaseAxisLen = bXDir ? (double )destBmp.Height : (double )destBmp.Width;

            for (int i = ; i < destBmp.Width; i++)

             {

                for (int j = ; j < destBmp.Height; j++)

                {

                    double dx = ;

                    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 = , nOldY = ;

                    nOldX = bXDir ? i + (int )(dy * dMultValue) : i;

                    nOldY = bXDir ? j : j + (int )(dy * dMultValue);

                    System.Drawing.Color color = srcBmp.GetPixel(i, j);

                    if (nOldX >=  && nOldX < destBmp.Width

                     && nOldY >=  && 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 = ; i < ; 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()),), x1, y1, x2, y2);

                }

                Font font = new System.Drawing.Font ("Times New Roman" , , System.Drawing.FontStyle .Bold);

                 LinearGradientBrush brush = new LinearGradientBrush (new Rectangle (, , image.Width, image.Height), Color .Blue, Color .DarkRed, 1.2f, true );

                if (_codetype != CodeType .Words)

                {

                    for (int i = ; i < checkCode.Length; i++)

                    {

                        g.DrawString(checkCode.Substring(i, ), font, brush,  + i * _jianju, );

                    }

                }else {

                    g.DrawString(checkCode, font, brush, , );

                }

                // 画图片的前景噪音点

                for (int i = ; i < ; 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 , , );

                }

                // 画图片的边框线

                g.DrawRectangle(new Pen (Color .Silver), , , image.Width - , image.Height - );

                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 ;

}

http://blog.csdn.net/chuangxin/article/details/5421903