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 ;
}