验证码

 /// <summary>
    /// 验证码生成
    /// </summary>
    public class VerificationCodeHelper
    {  //定义颜色
       //private static Color[] colors = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple };
        private static Color[] colors = { Color.Black };
        //定义验证码字符及出现频次 ,避免出现0 o j i l 1 x;  
        private static String charCollection = "ASDFGHZCVBNMKQWERTYUP";
        //缓存标识
        private static string cacheFlag = "CH_WebLoginVCode";
        //字体大小
        private static int fontSize = 25;
        //旋转角度
        private static int angle = 38;

        /// <summary>
        /// 验证码生成
        /// </summary>
        /// <param name="length">字符个数</param>
        /// <param name="width">宽度</param>
        /// <param name="height">高度</param>
        /// <returns></returns>
        public static byte[] GetBitmapCode(int width = 130, int height = 50, int length = 4)
        {
            string codes = "";
            string code = "";
            int codeX = width / (length + 1);
            Random random = new Random();
            using (Bitmap image = new Bitmap(width, height))
            {
                using (Graphics g = Graphics.FromImage(image))
                {
                    //清空图片背景色 
                    g.Clear(Color.FromArgb(247, 247, 247));
                    g.FillRectangle(new SolidBrush(Color.FromArgb(247, 247, 247)), 0, 0, image.Width, image.Height);
                    //画图片的背景噪音线 
                    for (int i = 0; i < 5; i++)
                    {
                        g.DrawLine(new Pen(colors[random.Next(colors.Length)]), random.Next(image.Width), random.Next(image.Height), random.Next(image.Width), random.Next(image.Height));
                    }


                    //文字距中  
                    StringFormat format = new StringFormat(StringFormatFlags.NoClip);
                    format.Alignment = StringAlignment.Center;
                    format.LineAlignment = StringAlignment.Near;

                    using (Font f = new Font("宋体", fontSize, System.Drawing.FontStyle.Regular))
                    {
                        using (Brush b = new SolidBrush(colors[random.Next(colors.Length)]))
                        {
                            for (int i = 0; i < length; i++)
                            {
                                code = charCollection[random.Next(0, charCollection.Length)].ToString();
                                SizeF sizeF = g.MeasureString(code, f);
                                PointF dot = new PointF(codeX, random.Next(image.Height / 2));

                                g.TranslateTransform(dot.X, dot.Y);//移动光标到指定位置  
                                int rAngel = random.Next(-angle, angle);
                                g.RotateTransform(rAngel);


                                g.DrawString(code, f, b, 1, 1, format);

                                g.RotateTransform(-rAngel);//转回去  
                                g.TranslateTransform(2, -dot.Y);//移动光标到指定位置  

                                codes += code;
                            }
                        }

                    }



                    //返回图片数据
                    using (System.IO.MemoryStream ms = new System.IO.MemoryStream())
                    {
                        image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
                        SaveToChache(codes);
                        return ms.ToArray();
                    }
                }
            }
        }

        /// <summary>
        /// 贝塞尔曲线
        /// </summary>  
        /// <returns></returns>
        public static int CreateImages(Graphics g, int beginX, int endX, int endY, int height)
        {
            Random random = new Random();
            //起始点坐标
            int beginx = beginX;
            int endx = endX;

            int beginy = random.Next(height);
            int endy = endY;


            //计算中间点Y最大位置
            int maxDianY = height / 2;
            int minDianY = 0;
            if (endY > maxDianY)
            {
                minDianY = maxDianY;
                maxDianY = height;
            }


            //中间点
            int dian1x = random.Next(beginX, endX);
            int dian2x = random.Next(endX);

            int dian1y = random.Next(minDianY, maxDianY);
            int dian2y = random.Next(minDianY, maxDianY);


            LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, endX, height), Color.Black, Color.Black, 1.2f, true);
            g.DrawBezier(new Pen(brush), beginx, beginy, dian1x, dian1y, dian2x, dian2y, endx, endy);

            return endy;
        }


        /// <summary>
        /// 保存验证码到内存中
        /// </summary> 
        /// <param name="code"></param>
        public static void SaveToChache(string code)
        {
            CacheHelper.Set(cacheFlag, code);
        }

        /// <summary>
        /// 验证验证码是否已过期
        /// </summary>
        /// <returns></returns>
        public static bool CheckCodeIsExpire()
        {
            return CacheHelper.Get(cacheFlag) == null;
        }

        /// <summary>
        /// 验证验证码是否正确
        /// </summary> 
        /// <param name="code"></param>
        /// <returns></returns>
        public static bool CheckCodeIsOK(string code)
        {
            string cacheCode = CacheHelper.Get(cacheFlag) as string;
            if (cacheCode == null)
            {
                return false;
            }
            if (cacheCode.Equals(code, StringComparison.OrdinalIgnoreCase) == false)
            {
                CacheHelper.Remove(cacheFlag);
                return false;
            }
            return true;
        }
    }