asp.net 验证码的方法和调用

最新推荐文章于 2026-01-08 20:07:11 发布

转载最新推荐文章于 2026-01-08 20:07:11 发布 · 1.1k 阅读

文章标签：

#asp.net #string #session #byte #random #c

ASP.NET 专栏收录该内容

15 篇文章

订阅专栏

本文介绍了一种使用C#生成包含随机字符的验证码图片的方法，并详细解释了如何设置图片大小、添加干扰线与点以及如何将字符绘制到图片上。

public byte[] GetImg(int keyLen,ref string strKey)
        {
            Random rd=new Random((int)System.DateTime.Now.Ticks);

            int widthImg=13*keyLen+5;
            int heightImg = 25;
            System.Drawing.Bitmap  bmp = new System.Drawing.Bitmap(widthImg,heightImg);
            System.Drawing.Graphics graphics = System.Drawing.Graphics.FromImage(bmp);
            //填充背景
            graphics.FillRectangle(new System.Drawing.SolidBrush(System.Drawing.Color.Black),0,0,widthImg,heightImg);

            //噪音线
            int nLine = keyLen * 2;
            System.Drawing.Pen pen= new System.Drawing.Pen(System.Drawing.Color.SkyBlue);
            for (int i = 0; i < nLine; i ++)
            {
                int x1 = rd.Next(widthImg);
                int x2 = rd.Next(widthImg);
                int y1 = rd.Next(heightImg);
                int y2 = rd.Next(heightImg);
                graphics.DrawLine(pen,x1,y1,x2,y2);
            }
            //验证码取值范围
            string strKeyFrom = "ABCDEFGHIJKNMPQRSTUVWXYZ23456789";
            //验证字串获取，放入strResult和graphics
            string strResult = "";
            for (int i = 0; i < keyLen; i ++)
            {
                int x = (i * 13 + rd.Next(3));
                int y = rd.Next(4)+1;

                char c = strKeyFrom[rd.Next(strKeyFrom.Length)];//随即字符
                strResult = strResult + c.ToString();
                //随即字符画入
                System.Drawing.Font font = new System.Drawing.Font("Arial",12 + rd.Next(1));
                graphics.DrawString(c.ToString(),font,new System.Drawing.SolidBrush(System.Drawing.Color.White),x,y);
            }
            //噪音点
            int nPixel = keyLen * 5;
            for (int i = 0; i < nPixel; i ++)
            {
                int x = rd.Next(widthImg);
                int y = rd.Next(heightImg);
                bmp.SetPixel(x,y,System.Drawing.Color.SkyBlue);
            }
            //输出
            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            bmp.Save(ms,System.Drawing.Imaging.ImageFormat.Gif);

            strKey=strResult;//获得验证码

            byte[] byteAry = ms.ToArray();

            bmp.Dispose();
            graphics.Dispose();
            ms.Close();

            return byteAry;

        }

调用

string strKey="";
            byte[] gifByteAry=aa.GetImg(5,ref strKey);
            Session["strKey"]=strKey;//注意放入Session变量
            Response.OutputStream.Write(gifByteAry,0,gifByteAry.Length);//输出流直接写出，非文字