/// <summary>
        /// 根据单号生成二维码
        /// </summary>
        /// <param name="strData"></param>
        /// <returns></returns>
        public static string _getQR(string strData)
        {
            string str = "";
            QRCodeEncoder qrCodeEncoder = new QRCodeEncoder();
            qrCodeEncoder.QRCodeEncodeMode = QRCodeEncoder.ENCODE_MODE.BYTE;
            qrCodeEncoder.QRCodeScale = 3;
            qrCodeEncoder.QRCodeVersion = 3;
            qrCodeEncoder.QRCodeErrorCorrect = QRCodeEncoder.ERROR_CORRECTION.M;
            System.Drawing.Image image = qrCodeEncoder.Encode(strData);
            string filename = DateTime.Now.ToString("yyyymmddhhmmssfff").ToString() + ".jpg";
            string filepath = HttpContext.Current.Server.MapPath(@"~\Images") + "\\" + 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);
            fs.Close();
            image.Dispose();
            str = @"/Images/" + filename;
            return str;
        }
//下载ThoughtWorks.QRCode.dll
原文:http://www.cnblogs.com/niguang/p/6232595.html