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
  }
}

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