生成验证码的图片

关于生成验证码的代码 网上很多

这里就只弄个生成验证码图片的代码

生成效果

 

        /// <summary>

        /// 生成图片验证码

        /// </summary>

        /// <param name="iCount">验证码的字符数(注意: 一个汉字为两个字符)</param>

        /// <param name="sValidate">验证码</param>

        /// <returns>图片字节流</returns>

        public static byte[] CreateImage(int iCount, string sValidate)

        {

            int iBmpWidth = 13 * iCount + 5;

            int iBmpHeight = 25;

            Bitmap bmp = new Bitmap(iBmpWidth, iBmpHeight);

 

            //生成随机背景颜色

            int iRed, iGreen, iBlue;  // 背景的三元色

            Random rd = new Random((int)System.DateTime.Now.Ticks);

            iRed = rd.Next(255) % 128 + 128;

            iGreen = rd.Next(255) % 128 + 128;

            iBlue = rd.Next(255) % 128 + 128;

 

            //填充位图背景

            Graphics graph = Graphics.FromImage(bmp);

            graph.FillRectangle(new SolidBrush(Color.FromArgb(iRed, iGreen, iBlue)), 0, 0, iBmpWidth, iBmpHeight);

 

            //绘制干扰线条，采用比背景略深一些的颜色

            Pen pen = new Pen(Color.FromArgb(iRed - 17, iGreen - 17, iBlue - 17), 2);

            for (int a = 0; a < 3; a++)

            {

                int x1 = rd.Next() % iBmpWidth;

                int y1 = rd.Next() % iBmpHeight;

                int x2 = rd.Next() % iBmpWidth;

                int y2 = rd.Next() % iBmpHeight;

                graph.DrawLine(pen, x1, y1, x2, y2);

            }

 

            //生成字体

            Font font = new Font("Courier New", 12 + rd.Next() % 4, FontStyle.Bold);

 

            //绘图

            graph.DrawString(sValidate, font, new SolidBrush(Color.FromArgb(iRed - 60, iGreen - 60, iBlue - 40)), 2, 3);

 

            System.IO.MemoryStream bstream = new System.IO.MemoryStream();

            bmp.Save(bstream, System.Drawing.Imaging.ImageFormat.Jpeg);

 

            bmp.Dispose();

            graph.Dispose();

 

            byte[] byteReturn = bstream.ToArray();

            bstream.Close();

 

            return byteReturn;

        }

需要注意的是，如果是用Session保存验证码，在验证成功后，记得把保存验证码的 Session清空掉.否则就可以跳过验证码，就失去验证码的意义了。