原文地址：http://www.cnblogs.com/tianguook/p/4142346.html
首先感谢aparche大牛的帖子，因为过两天可能要做个登录的页面，因此，需要用到验证码，从而看到了大神的这篇帖子，十分感谢。
产生验证码的类ValidCode
public class ValidCode
{
public enum CodeType { Words, Numbers, Characters, Alphas } private const double PI = 3.1415926535897932384626433832795;
private const double PI2 = 6.283185307179586476925286766559; private int _len;
private CodeType _codetype;
private readonly Single _jianju = (float)18.0;
private readonly Single _height = (float)24.0;
private string _checkCode; public string CheckCode
{
get
{
return _checkCode;
}
} private string returnCode = ""; public string ReturnCode
{
get
{
return returnCode;
} set
{
returnCode = value;
}
}
/// <summary>
/// 构造函数
/// </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;
} private string GenerateNumbers()
{
Random random = new Random();
for (int i = ; i < _len; i++)
{
string num = Convert.ToString(random.Next() % );
ReturnCode += num;
}
return ReturnCode.Trim();
} private string GenerateCharacters()
{
string num = "";
Random random = new Random();
for (int i = ; i < _len; i++)
{
if (random.Next() % == )
{
num = Convert.ToString((char)( + random.Next() % ));
}
else
{
num = Convert.ToString((char)( + random.Next() % ));
}
ReturnCode += num;
}
return ReturnCode.Trim();
} private string GenerateAlphas()
{
string num = "";
Random random = new Random();
for (int i = ; i < _len; i++)
{
if (random.Next() % == )
{
num = Convert.ToString(random.Next() % );
}
else if (random.Next() % == )
{
num = Convert.ToString((char)( + random.Next() % ));
}
else
{
num = Convert.ToString((char)( + random.Next() % ));
}
ReturnCode += num;
}
return ReturnCode.Trim();
} private Bitmap TwistImage(Bitmap srcBmp, bool bXDir, double dMultValue, double dPhase)
{
Bitmap destBmp = new Bitmap(srcBmp.Width, srcBmp.Height);
//将位图背景填充为白色
Graphics graph = 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;
} 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 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 Font("Times New Roman", , 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 MemoryStream();
image.Save(ms, ImageFormat.Gif);
}
finally
{
g.Dispose();
image.Dispose();
}
return ms;
}
}
修改内容如下：
1、大小写混合随机出现
原文都是用大写出现的，而我们常见的验证码都有大小写同时出现的情况，因此，在代码里多写了一句“num = Convert.ToString((char)(97 + random.Next(10000) % 26));”其中97是a的ASCII值。
2、增加一个返回的属性ReturnCode
原文在每段代码里都声明了一个strOut，而最后生成的是图片，如果再去解析图片的话，就得不偿失了，因此，增加一个属性，把相应的部分，进行替换，在调用的时候方便了取数。
调用页面的CS代码，写了一个MouseLeftButtonUp事件，可以在鼠标点击的时候，进行验证码变换。
public partial class MainWindow : Window
{
ValidCode validCode;
public MainWindow()
{
InitializeComponent();
validCode = new ValidCode(, ValidCode.CodeType.Alphas);
image1.Source = BitmapFrame.Create(validCode.CreateCheckCodeImage());
} private void image1_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
validCode = new ValidCode(, ValidCode.CodeType.Alphas);
image1.Source = BitmapFrame.Create(validCode.CreateCheckCodeImage());
} private void btn1_Click(object sender, RoutedEventArgs e)
{
if (txtbox1.Text.ToUpper() == validCode.ReturnCode.ToUpper())
MessageBox.Show("输入验证码正确");
else
MessageBox.Show("输入验证码错误");
}
}
实现效果图