C#生成漂亮验证码完整代码类

话不多说，请看代码：

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[] { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' };
     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[] { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' };
     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
 }
}

来源：http://www.cnblogs.com/rushme/p/6597629.html