ASP.NET实现验证码图片

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2021-04-08 13:02:57
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摘要: 新建一个checkcode.aspx文件,页面中不用写任何东西,在代码中,Page_Load中写入如下代码: string chkCode = string.Empty; int ix, iy; ix = 80; iy = 24; //颜色列表,用于验证码、噪线、噪点

新建一个checkcode.aspx文件,页面中不用写任何东西,在代码中,Page_Load中写入如下代码:

        string chkCode = string.Empty;
        int ix, iy;
        ix = 80;
        iy = 24;
        //颜色列表,用于验证码、噪线、噪点  
        Color[] color ={ Color.Black, Color.Red, Color.Blue, Color.Green, Color.Orange, Color.Brown, Color.Brown, Color.DarkBlue };  
        //字体列表,用于验证码  
        string[] font ={ "Times New Roman", "MS Mincho", "Book Antiqua", "Gungsuh", "MingLiU", "Arial" };  
        //验证码的字符集,去掉了一些容易混淆的字符  
        char[] character ={ ‘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 rnd = new Random();  
        //生成验证码字符串  
        for (int i = 0; i < 4; i++)  
        {  
            chkCode += character[rnd.Next(character.Length)];  
        }  
        Bitmap bmp = new Bitmap(ix, iy);  
        Graphics g = Graphics.FromImage(bmp);  
        g.Clear(Color.White);  
        //画噪线  
        for (int i = 0; i < 10; i++)  
        {  
            int x1 = rnd.Next(ix);  
            int y1 = rnd.Next(iy);  
            int x2 = rnd.Next(ix);  
            int y2 = rnd.Next(iy);  
            Color clr = color[rnd.Next(color.Length)];  
            g.DrawLine(new Pen(clr), x1, y1, x2, y2);  
        }  
        //画验证码字符串  
        for (int i = 0; i < chkCode.Length; i++)  
        {  
            string fnt = font[rnd.Next(font.Length)];  
            Font ft = new Font(fnt, 14, FontStyle.Bold);  
            Color clr = color[rnd.Next(color.Length)];  
            g.DrawString(chkCode[i].ToString(), ft, new SolidBrush(clr), (float)i * 16 + 2, (float)2);  
        }  
        //画噪点  
        for (int i = 0; i < 50; i++)  
        {  
            int x = rnd.Next(bmp.Width);  
            int y = rnd.Next(bmp.Height);  
            Color clr = color[rnd.Next(color.Length)];  
            bmp.SetPixel(x, y, clr);  
        }
        //将验证码写入SESSION
        Session["checkcode"] = chkCode.ToLower();
        //清除该页输出缓存,设置该页无缓存  
        Response.Buffer = true;  
        Response.ExpiresAbsolute = System.DateTime.Now.AddMilliseconds(0);  
        Response.Expires = 0;  
        Response.CacheControl = "no-cache";  
        Response.AppendHeader("Pragma", "No-Cache");  
        //将验证码图片写入内存流,并将其以 "image/Png" 格式输出  
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