.NET 验证码/验证图片

 /// <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();
             string result = "";
             System.Random random = new Random();
             for (int i = ; i < Length; i++)
             {
                 result += random.Next().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();
             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 = ; i < Length; i++)
             {
                 int rnd = random.Next(, 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();
             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 = ; i < Length; i++)
             {
                 int rnd = random.Next(, n);
                 result += Pattern[rnd];
             }
             return result;
         }
         #endregion
     }

     /// <summary>
     /// 验证图片类
     /// </summary>
     public class CheckCodeHelper
     {
         #region 私有字段
         private string text;
         private Bitmap image;
         private int letterCount = ;   //验证码位数
         private int letterWidth = ;  //单个字体的宽度范围
         private int letterHeight = ; //单个字体的高度范围
         private static byte[] randb = new byte[];
         private static RNGCryptoServiceProvider rand = new RNGCryptoServiceProvider();
         private Font[] fonts =
             {
                new Font(new FontFamily("Times New Roman"), +Next(),System.Drawing.FontStyle.Regular),
                new Font(new FontFamily("Georgia"),  + Next(),System.Drawing.FontStyle.Regular),
                new Font(new FontFamily("Arial"),  + Next(),System.Drawing.FontStyle.Regular),
                new Font(new FontFamily("Comic Sans MS"),  + Next(),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 CheckCodeHelper()
         {
             //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();
             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, );
             value = value % (max + );
             if (value < ) 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 = ; i < ; i++)
             {
                 int x1 = Next(image.Width - );
                 int x2 = Next(image.Width - );
                 int y1 = Next(image.Height - );
                 int y2 = Next(image.Height - );
                 g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
             }
             int _x = -, _y = ;
             for (int int_index = ; int_index < this.text.Length; int_index++)
             {
                 _x += Next(, );
                 _y = Next(-, );
                 string str_char = this.text.Substring(int_index, );
                 str_char = Next() ==  ? 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 - )], newBrush, thePos);
             }
             for (int i = ; i < ; i++)
             {
                 int x = Next(image.Width - );
                 int y = Next(image.Height - );
                 image.SetPixel(x, y, Color.FromArgb(Next(, ), Next(, ), Next(, )));
             }
             image = TwistImage(image, true, Next(, ), Next(, ));
             g.DrawRectangle(new Pen(Color.LightGray, ), , , int_ImageWidth - , (letterHeight - ));
             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());
             Random RandomNum_Sencond = new Random((int)DateTime.Now.Ticks);
             int int_Red = RandomNum_First.Next();
             int int_Green = RandomNum_Sencond.Next();
             int int_Blue = (int_Red + int_Green > ) ?  :  - int_Red - int_Green;
             int_Blue = (int_Blue > ) ?  : 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), , , 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 ? (PI * (double)j) / dBaseAxisLen : (PI * (double)i) / dBaseAxisLen;
                     dx += dPhase;
                     double dy = Math.Sin(dx);
                     int nOldX = , nOldY = ;
                     nOldX = bXDir ? i + (int)(dy * dMultValue) : i;
                     nOldY = bXDir ? j : j + (int)(dy * dMultValue);

                     Color color = srcBmp.GetPixel(i, j);
                     if (nOldX >=  && nOldX < destBmp.Width
                      && nOldY >=  && nOldY < destBmp.Height)
                     {
                         destBmp.SetPixel(nOldX, nOldY, color);
                     }
                 }
             }
             srcBmp.Dispose();
             return destBmp;
         }
         #endregion
     }