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Editor to share with you how to achieve ASP.NET CAPTCHA and refresh CAPTCHA, I believe most people do not know much about it, so share this article for your reference, I hope you can learn a lot after reading this article, let's go to know it!

Implementation code

/ / /

/ / generate a CAPTCHA image and save the session name VerificationCode

/ / /

Public static void CreateVerificationCode ()

{

Int number

String checkCode = string.Empty

/ / Random number seed

Random randoms = new Random ()

For (int I = 0; I

< 4; i++) //校验码长度为4 { //随机的整数 number = randoms.Next(); //字符从0-9,A-Z中随机产生,对应的ASCII码分别为 //48-57,65-90 number = number % 36; if (number < 10) { number += 48; } else { number += 55; } checkCode += ((char)number).ToString(); } //在session中保存校验码 System.Web.HttpContext.Current.Session["VerificationCode"] = checkCode; //若校验码为空，则直接返回 if (checkCode == null || checkCode.Trim() == String.Empty) { return; } //根据校验码的长度确定输出图片的长度 System.Drawing.Bitmap image = new System.Drawing.Bitmap(55, 20);//(int)Math.Ceiling(Convert.ToDouble(checkCode.Length * 15)) //创建Graphics对象 Graphics g = Graphics.FromImage(image); try { //生成随机数种子 Random random = new Random(); //清空图片背景色 g.Clear(Color.White); //画图片的背景噪音线 10条 //--------------------------------------------------- for (int i = 0; i < 10; i++) { //噪音线起点坐标(x1,y1),终点坐标(x2,y2) int x1 = random.Next(image.Width); int x2 = random.Next(image.Width); int y1 = random.Next(image.Height); int y2 = random.Next(image.Height); //用银色画出噪音线 g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2); } //--------------------------------------------------- //Brush b = Brushes.Silver; //g.FillRectangle(b, 0, 0, image.Width, image.Height); //---------------------以上两种任选其一------------------------------ //输出图片中校验码的字体: 12号Arial,粗斜体 Font font = new Font("Arial", 12, (FontStyle.Bold | FontStyle.Italic)); //线性渐变画刷 LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.Purple, 1.2f, true); g.DrawString(checkCode, font, brush, 2, 2); //画图片的前景噪音点 50个 for (int i = 0; i < 50; i++) { int x = random.Next(image.Width); int y = random.Next(image.Height); image.SetPixel(x, y, Color.FromArgb(random.Next())); } //画图片的边框线 g.DrawRectangle(new Pen(Color.Peru), 0, 0, image.Width - 1, image.Height - 1); //创建内存流用于输出图片 using (MemoryStream ms = new MemoryStream()) { //图片格式指定为png image.Save(ms, ImageFormat.Jpeg); //清除缓冲区流中的所有输出 System.Web.HttpContext.Current.Response.ClearContent(); //输出流的HTTP MIME类型设置为"image/Png" System.Web.HttpContext.Current.Response.ContentType = "image/Jpeg"; //输出图片的二进制流 System.Web.HttpContext.Current.Response.BinaryWrite(ms.ToArray()); } } finally { //释放Bitmap对象和Graphics对象 g.Dispose(); image.Dispose(); } } 创建一个aspx页面 代码如下: 添加HTML代码,引用 代码如下: 验证码： *

How to achieve refresh?

The code is as follows:

$("# imgAuthCode") .click (function () {

$(this) .attr ("src", "AuthCode.aspx?code=" + (new Date ()) .getTime ())

});

Effect picture

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