C# Winform验证码

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
	}
}

使用:

ValidCode validCode = new ValidCode (5, ValidCode .CodeType .Numbers)

// 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 ;

  }

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