Partage complet d'exemples de code pour C# afin de générer un superbe code de vérification

using System;
using System.Web;
using System.Drawing;
using System.Security.Cryptography;
namespace DotNet.Utilities
{
  /// <summary>
  /// 验证码类
  /// </summary>
  public class Rand
  {
    #region 生成随机数字
    /// <summary>
    /// 生成随机数字
    /// </summary>
    /// <param name="length">生成长度</param>
    public static string Number(int Length)
    {
      return Number(Length, false);
    }
    /// <summary>
    /// 生成随机数字
    /// </summary>
    /// <param name="Length">生成长度</param>
    /// <param name="Sleep">是否要在生成前将当前线程阻止以避免重复</param>
    public static string Number(int Length, bool Sleep)
    {
      if (Sleep) System.Threading.Thread.Sleep(3);
      string result = "";
      System.Random random = new Random();
      for (int i = 0; i < Length; i++)
      {
        result += random.Next(10).ToString();
      }
      return result;
    }
    #endregion
    #region 生成随机字母与数字
    /// <summary>
    /// 生成随机字母与数字
    /// </summary>
    /// <param name="IntStr">生成长度</param>
    public static string Str(int Length)
    {
      return Str(Length, false);
    }
    /// <summary>
    /// 生成随机字母与数字
    /// </summary>
    /// <param name="Length">生成长度</param>
    /// <param name="Sleep">是否要在生成前将当前线程阻止以避免重复</param>
    public static string Str(int Length, bool Sleep)
    {
      if (Sleep) System.Threading.Thread.Sleep(3);
      char[] Pattern = new char[] { &#39;0&#39;, &#39;1&#39;, &#39;2&#39;, &#39;3&#39;, &#39;4&#39;, &#39;5&#39;, &#39;6&#39;, &#39;7&#39;, &#39;8&#39;, &#39;9&#39;, &#39;A&#39;, &#39;B&#39;, &#39;C&#39;, &#39;D&#39;, &#39;E&#39;, &#39;F&#39;, &#39;G&#39;, &#39;H&#39;, &#39;I&#39;, &#39;J&#39;, &#39;K&#39;, &#39;L&#39;, &#39;M&#39;, &#39;N&#39;, &#39;O&#39;, &#39;P&#39;, &#39;Q&#39;, &#39;R&#39;, &#39;S&#39;, &#39;T&#39;, &#39;U&#39;, &#39;V&#39;, &#39;W&#39;, &#39;X&#39;, &#39;Y&#39;, &#39;Z&#39; };
      string result = "";
      int n = Pattern.Length;
      System.Random random = new Random(~unchecked((int)DateTime.Now.Ticks));
      for (int i = 0; i < Length; i++)
      {
        int rnd = random.Next(0, n);
        result += Pattern[rnd];
      }
      return result;
    }
    #endregion
    #region 生成随机纯字母随机数
    /// <summary>
    /// 生成随机纯字母随机数
    /// </summary>
    /// <param name="IntStr">生成长度</param>
    public static string Str_char(int Length)
    {
      return Str_char(Length, false);
    }
    /// <summary>
    /// 生成随机纯字母随机数
    /// </summary>
    /// <param name="Length">生成长度</param>
    /// <param name="Sleep">是否要在生成前将当前线程阻止以避免重复</param>
    public static string Str_char(int Length, bool Sleep)
    {
      if (Sleep) System.Threading.Thread.Sleep(3);
      char[] Pattern = new char[] { &#39;A&#39;, &#39;B&#39;, &#39;C&#39;, &#39;D&#39;, &#39;E&#39;, &#39;F&#39;, &#39;G&#39;, &#39;H&#39;, &#39;I&#39;, &#39;J&#39;, &#39;K&#39;, &#39;L&#39;, &#39;M&#39;, &#39;N&#39;, &#39;O&#39;, &#39;P&#39;, &#39;Q&#39;, &#39;R&#39;, &#39;S&#39;, &#39;T&#39;, &#39;U&#39;, &#39;V&#39;, &#39;W&#39;, &#39;X&#39;, &#39;Y&#39;, &#39;Z&#39; };
      string result = "";
      int n = Pattern.Length;
      System.Random random = new Random(~unchecked((int)DateTime.Now.Ticks));
      for (int i = 0; i < Length; i++)
      {
        int rnd = random.Next(0, n);
        result += Pattern[rnd];
      }
      return result;
    }
    #endregion
  }
  /// <summary>
  /// 验证图片类
  /// </summary>
  public class YZMHelper
  {
    #region 私有字段
    private string text;
    private Bitmap image;
    private int letterCount = 4;  //验证码位数
    private int letterWidth = 16; //单个字体的宽度范围
    private int letterHeight = 20; //单个字体的高度范围
    private static byte[] randb = new byte[4];
    private static RNGCryptoServiceProvider rand = new RNGCryptoServiceProvider();
    private Font[] fonts = 
  {
    new Font(new FontFamily("Times New Roman"),10 +Next(1),System.Drawing.FontStyle.Regular),
    new Font(new FontFamily("Georgia"), 10 + Next(1),System.Drawing.FontStyle.Regular),
    new Font(new FontFamily("Arial"), 10 + Next(1),System.Drawing.FontStyle.Regular),
    new Font(new FontFamily("Comic Sans MS"), 10 + Next(1),System.Drawing.FontStyle.Regular)
  };
    #endregion
    #region 公有属性
    /// <summary>
    /// 验证码
    /// </summary>
    public string Text
    {
      get { return this.text; }
    }
    /// <summary>
    /// 验证码图片
    /// </summary>
    public Bitmap Image
    {
      get { return this.image; }
    }
    #endregion
    #region 构造函数
    public YZMHelper()
    {
      HttpContext.Current.Response.Expires = 0;
      HttpContext.Current.Response.Buffer = true;
HttpContext.Current.Response.ExpiresAbsolute = DateTime.Now.AddSeconds(-1);
      HttpContext.Current.Response.AddHeader("pragma", "no-cache");
      HttpContext.Current.Response.CacheControl = "no-cache";
      this.text = Rand.Number(4);
      CreateImage();
    }
    #endregion
    #region 私有方法
    /// <summary>
    /// 获得下一个随机数
    /// </summary>
    /// <param name="max">最大值</param>
    private static int Next(int max)
    {
      rand.GetBytes(randb);
      int value = BitConverter.ToInt32(randb, 0);
      value = value % (max + 1);
      if (value < 0) value = -value;
      return value;
    }
    /// <summary>
    /// 获得下一个随机数
    /// </summary>
    /// <param name="min">最小值</param>
    /// <param name="max">最大值</param>
    private static int Next(int min, int max)
    {
      int value = Next(max - min) + min;
      return value;
    }
    #endregion
    #region 公共方法
    /// <summary>
    /// 绘制验证码
    /// </summary>
    public void CreateImage()
    {
      int int_ImageWidth = this.text.Length * letterWidth;
      Bitmap image = new Bitmap(int_ImageWidth, letterHeight);
      Graphics g = Graphics.FromImage(image);
      g.Clear(Color.White);
      for (int i = 0; i < 2; i++)
      {
        int x1 = Next(image.Width - 1);
        int x2 = Next(image.Width - 1);
        int y1 = Next(image.Height - 1);
        int y2 = Next(image.Height - 1);
        g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
      }
      int _x = -12, _y = 0;
      for (int int_index = 0; int_index < this.text.Length; int_index++)
      {
        _x += Next(12, 16);
        _y = Next(-2, 2);
        string str_char = this.text.Substring(int_index, 1);
        str_char = Next(1) == 1 ? str_char.ToLower() : str_char.ToUpper();
        Brush newBrush = new SolidBrush(GetRandomColor());
        Point thePos = new Point(_x, _y);
        g.DrawString(str_char, fonts[Next(fonts.Length - 1)], newBrush, thePos);
      }
      for (int i = 0; i < 10; i++)
      {
        int x = Next(image.Width - 1);
        int y = Next(image.Height - 1);
        image.SetPixel(x, y, Color.FromArgb(Next(0, 255), Next(0, 255), Next(0, 255)));
      }
      image = TwistImage(image, true, Next(1, 3), Next(4, 6));
      g.DrawRectangle(new Pen(Color.LightGray, 1), 0, 0, int_ImageWidth - 1, (letterHeight - 1));
      this.image = image;
    }
    /// <summary>
    /// 字体随机颜色
    /// </summary>
    public Color GetRandomColor()
    {
      Random RandomNum_First = new Random((int)DateTime.Now.Ticks);
      System.Threading.Thread.Sleep(RandomNum_First.Next(50));
      Random RandomNum_Sencond = new Random((int)DateTime.Now.Ticks);
      int int_Red = RandomNum_First.Next(180);
      int int_Green = RandomNum_Sencond.Next(180);
      int int_Blue = (int_Red + int_Green > 300) ? 0 : 400 - int_Red - int_Green;
      int_Blue = (int_Blue > 255) ? 255 : int_Blue;
      return Color.FromArgb(int_Red, int_Green, int_Blue);
    }
    /// <summary>
    /// 正弦曲线Wave扭曲图片
    /// </summary>
    /// <param name="srcBmp">图片路径</param>
    /// <param name="bXDir">如果扭曲则选择为True</param>
    /// <param name="nMultValue">波形的幅度倍数，越大扭曲的程度越高,一般为3</param>
    /// <param name="dPhase">波形的起始相位,取值区间[0-2*PI)</param>
    public System.Drawing.Bitmap TwistImage(Bitmap srcBmp, bool bXDir, double dMultValue, double dPhase)
    {
      double PI = 6.283185307179586476925286766559;
      Bitmap destBmp = new Bitmap(srcBmp.Width, srcBmp.Height);
      Graphics graph = Graphics.FromImage(destBmp);
      graph.FillRectangle(new SolidBrush(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 ? (PI * (double)j) / dBaseAxisLen : (PI * (double)i) / dBaseAxisLen;
          dx += dPhase;
          double dy = Math.Sin(dx);
          int nOldX = 0, nOldY = 0;
          nOldX = bXDir ? i + (int)(dy * dMultValue) : i;
          nOldY = bXDir ? j : j + (int)(dy * dMultValue);
          Color color = srcBmp.GetPixel(i, j);
          if (nOldX >= 0 && nOldX < destBmp.Width
           && nOldY >= 0 && nOldY < destBmp.Height)
          {
            destBmp.SetPixel(nOldX, nOldY, color);
          }
        }
      }
      srcBmp.Dispose();
      return destBmp;
    }
    #endregion
  }
}