第一种情况：将二维码生成张图片保存到本地文件夹里

第一步：下载ThoughtWorks.QRCode.dll

添加引用using System.Text;
using ThoughtWorks.QRCode.Codec;
using System.Drawing;

第二步：建个相比入径的文件夹接收图片Upload

第三步：生成二维码保存到文件夹中访问

 string nr = "https://www.baidu.com/";
            QRCodeEncoder qrCodeEncoder = new QRCodeEncoder();
            qrCodeEncoder.QRCodeEncodeMode = QRCodeEncoder.ENCODE_MODE.BYTE;
            qrCodeEncoder.QRCodeScale = 4;
            qrCodeEncoder.QRCodeVersion = 8;
            qrCodeEncoder.QRCodeErrorCorrect = QRCodeEncoder.ERROR_CORRECTION.M;
            System.Drawing.Image image = qrCodeEncoder.Encode(nr);
            string filename = DateTime.Now.ToString("yyyymmddhhmmssfff").ToString() + ".jpg";
            string filepath = Server.MapPath(@"~\Upload") + "\\" + filename;
            System.IO.FileStream fs = new System.IO.FileStream(filepath, System.IO.FileMode.OpenOrCreate, System.IO.FileAccess.Write);
            image.Save(fs, System.Drawing.Imaging.ImageFormat.Jpeg);
            this.id1.ImageUrl = "~/Upload/" + filename;
            fs.Close();
            image.Dispose();

第二种情况：将链接绘制成二维码

第一步：下载ThoughtWorks.QRCode.dll

添加引用using System.Text;
using ThoughtWorks.QRCode.Codec;
using System.Drawing;

第二步：绘制二维码，并释放资源

 Bitmap bmp = null;
            try
            {
                QRCodeEncoder qrCodeEncoder = new QRCodeEncoder();
                qrCodeEncoder.QRCodeEncodeMode = QRCodeEncoder.ENCODE_MODE.BYTE;
                qrCodeEncoder.QRCodeScale = 4;
                //int version = Convert.ToInt16(cboVersion.Text);
                qrCodeEncoder.QRCodeVersion = 7;
                qrCodeEncoder.QRCodeErrorCorrect = QRCodeEncoder.ERROR_CORRECTION.M;
                bmp = qrCodeEncoder.Encode("https://www.baidu.com/");
            }
            catch (Exception ex)
            {
                //MessageBox.Show("Invalid version !");
            }

Bitmap img= bmp；
            System.Drawing.Graphics graphics = System.Drawing.Graphics.FromImage(img);
            //System.Drawing.Font font = new System.Drawing.Font("宋体", 16); //字体与大小
            //System.Drawing.Brush brush = new System.Drawing.SolidBrush(System.Drawing.Color.Red);
            //graphics.DrawString("www.cftea.com", font, brush, 50, 50); //写字，最后两个参数表示位置

            //将图片保存到内存流中
            System.IO.MemoryStream stream = new System.IO.MemoryStream();
            img.Save(stream, System.Drawing.Imaging.ImageFormat.Gif);

            //在页面上输出
            Response.Clear();
            Response.ContentType = "image/gif";
            Response.BinaryWrite(stream.ToArray());

            stream.Close();
            stream.Dispose();

            graphics.Dispose();
            img.Dispose();

            Response.End();