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 ;

 }

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。