C# winform登陆框验证码的实现方法

本文实例为大家分享了C# winform登陆框验证码的具体代码，供大家参考，具体内容如下

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 ;

}

来源：http://www.cnblogs.com/viuu/archive/2017/08/25/7429151.html