漂亮的验证码

using System.Text;
using System.IO;
using System.Drawing;
using System.Drawing.Imaging;

  protected void Page_Load(object sender, EventArgs e)
        {
            
            String sCode = String.Empty;
            //清除該頁輸出緩存，設置該頁無緩存
            Response.Buffer = true;
            Response.ExpiresAbsolute = System.DateTime.Now.AddMilliseconds(0);
            Response.Expires = 0;
            Response.CacheControl = "no-cache";
            Response.AppendHeader("Pragma", "No-Cache");

            // '將驗證碼圖片寫入記憶體流，並將其以 "image/Png" 格式輸出
            MemoryStream oStream = new MemoryStream();
            try
            {
                CreateValidateCodeImage(oStream, sCode, 4, 100, 40, 18);
                Session["_ValidateCode"] = sCode;
                Response.ClearContent();
                Response.ContentType = "image/Png";
                Response.BinaryWrite(oStream.ToArray());
            }
            finally
            {
                // '釋放資源
                oStream.Dispose();
            }
        }
        /// <summary>
        /// 產生圖形驗證碼。
        /// </summary>
        /// <param name="MemoryStream">記憶體資料流。</param>
        /// <param name="Code">傳出驗證碼。</param>
        /// <param name="CodeLength">驗證碼字元數。</param>
        /// <param name="Width"></param>
        /// <param name="Height"></param>
        /// <param name="FontSize"></param>
        public void CreateValidateCodeImage(MemoryStream MemoryStream, String Code, int CodeLength, int Width, int Height, int FontSize)
        {
            Bitmap oBmp;
            oBmp = CreateValidateCodeImage(Code, CodeLength, Width, Height, FontSize);
            try
            {
                oBmp.Save(MemoryStream, ImageFormat.Png);
            }
            finally { oBmp.Dispose(); }
        }
        /// <summary>
        /// 產生圖形驗證碼。
        /// </summary>
        /// <param name="Code">傳出驗證碼。</param>
        /// <param name="CodeLength">驗證碼字元數。</param>
        /// <param name="Width"></param>
        /// <param name="Height"></param>
        /// <param name="FontSize"></param>
        /// <returns></returns>
        public Bitmap CreateValidateCodeImage(String Code, int CodeLength, int Width, int Height, int FontSize)
        {
            String sCode = String.Empty;
            //顏色列表，用於驗證碼、噪線、噪點
            Color[] oColors ={
             System.Drawing.Color.Black,
             System.Drawing.Color.Red,
             System.Drawing.Color.Blue,
             System.Drawing.Color.Green,
             System.Drawing.Color.Orange,
             System.Drawing.Color.Brown,
             System.Drawing.Color.Brown,
             System.Drawing.Color.DarkBlue
            };
            //字體列表，用於驗證碼
            string[] oFontNames ={ "Times New Roman", "MS Mincho", "Book Antiqua", "Gungsuh", "PMingLiU", "Impact" };
            //驗證碼的字元集，去掉了一些容易混淆的字元
            char[] oCharacter = {
   '2',
   '3',
   '4',
   '5',
   '6',
   '8',
   '9',
   'A',
   'B',
   'C',
   'D',
   'E',
   'F',
   'G',
   'H',
   'J',
   'K',
   'L',
   'M',
   'N',
   'P',
   'R',
   'S',
   'T',
   'W',
   'X',
   'Y'
  };
            Random oRnd = new Random();
            Bitmap oBmp = null;
            Graphics oGraphics = null;
            int N1 = 0;
            System.Drawing.Point oPoint1 = default(System.Drawing.Point);
            System.Drawing.Point oPoint2 = default(System.Drawing.Point);
            string sFontName = null;
            Font oFont = null;
            Color oColor = default(Color);

            //生成驗證碼字串
            for (N1 = 0; N1 <= CodeLength - 1; N1++)
            {
                sCode += oCharacter[oRnd.Next(oCharacter.Length)];
            }

            oBmp = new Bitmap(Width, Height);
            oGraphics = Graphics.FromImage(oBmp);
            oGraphics.Clear(System.Drawing.Color.White);
            try
            {
                for (N1 = 0; N1 <= 4; N1++)
                {
                    //畫噪線
                    oPoint1.X = oRnd.Next(Width);
                    oPoint1.Y = oRnd.Next(Height);
                    oPoint2.X = oRnd.Next(Width);
                    oPoint2.Y = oRnd.Next(Height);
                    oColor = oColors[oRnd.Next(oColors.Length)];
                    oGraphics.DrawLine(new Pen(oColor), oPoint1, oPoint2);
                }

                for (N1 = 0; N1 <= sCode.Length - 1; N1++)
                {
                    //畫驗證碼字串
                    sFontName = oFontNames[oRnd.Next(oFontNames.Length)];
                    oFont = new Font(sFontName, FontSize, FontStyle.Italic);
                    oColor = oColors[oRnd.Next(oColors.Length)];
                    oGraphics.DrawString(sCode[N1].ToString(), oFont, new SolidBrush(oColor), Convert.ToSingle(N1) * FontSize + 10, Convert.ToSingle(8));
                }

                for (int i = 0; i <= 30; i++)
                {
                    //畫噪點
                    int x = oRnd.Next(oBmp.Width);
                    int y = oRnd.Next(oBmp.Height);
                    Color clr = oColors[oRnd.Next(oColors.Length)];
                    oBmp.SetPixel(x, y, clr);
                }

                Code = sCode;
                return oBmp;
            }
            finally
            {
                oGraphics.Dispose();
            }

        }

=====================================

改编自博友的原代码为C#

http://www.cnblogs.com/jeff377/archive/2008/10/29/1322471.html

效果图如下：

下载地址 /Files/ggbbeyou/改编验证码.rar