二维码图片以字符串的形式保存DB,已文件流显示页面上

以下是生成二维码的方法，我只用其中一个方法 这个需要引用ZXing.DLL 

链接：https://pan.baidu.com/s/1mCTwHiAm_awtsPcibAotZw
提取码：ufp6 

 public class QRcode
    {
        //需要引用ZXing.DLL  可以百度一下  一个很好用的二维码生成程序集《DLL文件啦》
        //使用案例：Bitmap img3 = GenByZXingNet("");
        //使用案例：img3.Save(Server.MapPath(@"\testImg\erweima.png"));
        /// <summary>
        /// 生成二维码
        /// </summary>
        /// <param name="msg">二维码信息</param>
        /// <param name="codeSizeInPixels">正方形 边长</param>
        /// <returns>图片</returns>
        public static Bitmap GenByZXingNet(string msg, int codeSizeInPixels = 250)
        {
            BarcodeWriter writer = new BarcodeWriter();
            writer.Format = BarcodeFormat.QR_CODE;
            writer.Options.Hints.Add(EncodeHintType.CHARACTER_SET, "UTF-8");//编码问题
            writer.Options.Hints.Add(EncodeHintType.ERROR_CORRECTION, ZXing.QrCode.Internal.ErrorCorrectionLevel.H);

            writer.Options.Height = writer.Options.Width = codeSizeInPixels;
            writer.Options.Margin = 0;//设置边框1            ZXing.Common.BitMatrix bm = writer.Encode(msg);
            Bitmap img = writer.Write(msg);
            return img;
        }

        #endregion

        #region C#生成带有Log的二维码
        /// <summary>
        /// 生成带Logo的二维码
        /// </summary>
        /// <param name="text">文本内容</param>
        static void Generate(string text, string LogoPth, string serverPth, ImageFormat imgFrt)
        {
            //Logo 图片
            Bitmap logo = new Bitmap(LogoPth);
            //构造二维码写码器
            MultiFormatWriter writer = new MultiFormatWriter();
            Dictionary<EncodeHintType, object> hint = new Dictionary<EncodeHintType, object>();
            hint.Add(EncodeHintType.CHARACTER_SET, "UTF-8");
            hint.Add(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.H);

            //生成二维码 
            BitMatrix bm = writer.encode(text, BarcodeFormat.QR_CODE, 300, 300, hint);
            BarcodeWriter barcodeWriter = new BarcodeWriter();
            Bitmap map = barcodeWriter.Write(bm);


            //获取二维码实际尺寸（去掉二维码两边空白后的实际尺寸）
            int[] rectangle = bm.getEnclosingRectangle();

            //计算插入图片的大小和位置
            int middleW = Math.Min((int)(rectangle[2] / 3.5), logo.Width);
            int middleH = Math.Min((int)(rectangle[3] / 3.5), logo.Height);
            int middleL = (map.Width - middleW) / 2;
            int middleT = (map.Height - middleH) / 2;

            //将img转换成bmp格式，否则后面无法创建Graphics对象
            Bitmap bmpimg = new Bitmap(map.Width, map.Height, PixelFormat.Format32bppArgb);
            using (Graphics g = Graphics.FromImage(bmpimg))
            {
                g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
                g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
                g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
                g.DrawImage(map, 0, 0);
            }
            //将二维码插入图片
            Graphics myGraphic = Graphics.FromImage(bmpimg);
            //白底
            myGraphic.FillRectangle(Brushes.White, middleL, middleT, middleW, middleH);
            myGraphic.DrawImage(logo, middleL, middleT, middleW, middleH);

            //保存成图片
            bmpimg.Save(serverPth, imgFrt);
        }
        #endregion

        #region ZXing生成条形码
        /// <summary>
        /// 文本内容
        /// </summary>
        /// <param name="text">只支持数字 只支持偶数个 最大长度80</param>
        /// <param name="ServerPTh">存储路径 @"H:\桌面\截图\generate2.png"</param>
        public static void Generate(string text, string ServerPth, ImageFormat imgFrt)
        {
            BarcodeWriter writer = new BarcodeWriter();
            //使用ITF 格式，不能被现在常用的支付宝、微信扫出来
            //如果想生成可识别的可以使用 CODE_128 格式
            //writer.Format = BarcodeFormat.ITF;
            writer.Format = BarcodeFormat.CODE_128;
            EncodingOptions options = new EncodingOptions()
            {
                Width = 150,
                Height = 50,
                Margin = 2
            };
            writer.Options = options;
            Bitmap map = writer.Write(text);
            string filename = ServerPth;//请注意 保存格式和文件扩展名一致性
            map.Save(filename, imgFrt);
        }


        /// <summary>
        /// 文本内容  生成条形码
        /// </summary>
        /// <param name="text">只支持数字 最大长度80</param>
        /// <param name="ServerPTh">文件夹名称</param>
        /// <param name="fileName">文件名</param>
        public static string GenerateTxm(string text, string category, string fileName, ImageFormat imgFrt)
        {
            var uploadPath = System.Configuration.ConfigurationSettings.AppSettings["UploadPath"];

            //文件保存目录路径 
            string dirTempPath = uploadPath + "//" + category;
            if (!Directory.Exists(dirTempPath))
            {
                Directory.CreateDirectory(dirTempPath);
            }
            string ServerPth = dirTempPath + "//" + fileName;//文件绝对路径
            BarcodeWriter writer = new BarcodeWriter();
            //使用ITF 格式，不能被现在常用的支付宝、微信扫出来
            //如果想生成可识别的可以使用 CODE_128 格式
            //writer.Format = BarcodeFormat.ITF;
            writer.Format = BarcodeFormat.CODE_128;
            EncodingOptions options = new EncodingOptions()
            {
                Width = 150,
                Height = 50,
                Margin = 2
            };
            writer.Options = options;
            Bitmap map = writer.Write(text);
            string filename = ServerPth;//请注意 保存格式和文件扩展名一致性
            map.Save(filename, imgFrt);
            return ServerPth;
        }
        #endregion

        #region 二维码 条形码读取
        /// <summary>
        /// 二维码 条形码读取
        /// </summary>
        /// <param name="filename">文件路径</param>
        /// <returns></returns>
        public static string Read(string filename)
        {
            BarcodeReader reader = new BarcodeReader();
            reader.Options.CharacterSet = "UTF-8";
            Bitmap map = new Bitmap(filename);
            Result result = reader.Decode(map);
            return result == null ? "" : result.Text;
        }
        #endregion

        #region C#生成特定颜色二维码-基础版本
        //需要引用ZXing.DLL  可以百度一下  一个很好用的二维码生成程序集《DLL文件啦》
        //使用案例：Bitmap img3 = GenByZXingNet("");
        //使用案例：img3.Save(Server.MapPath(@"\testImg\erweima.png"));
        /// <summary>
        /// 生成二维码
        /// </summary>
        /// <param name="msg">二维码信息</param>
        /// <param name="codeSizeInPixels">正方形 边长</param>
        /// <returns>图片</returns>
        public static Bitmap GenByZXingNet_Color(string msg, int codeSizeInPixels = 250)
        {
            BarcodeWriter writer = new BarcodeWriter();
            writer.Renderer = new ZXing.Rendering.BitmapRenderer { Background = Color.Red, Foreground = Color.Blue };
            writer.Format = BarcodeFormat.QR_CODE;
            writer.Options.Hints.Add(EncodeHintType.CHARACTER_SET, "UTF-8");//编码问题
            writer.Options.Hints.Add(EncodeHintType.ERROR_CORRECTION, ZXing.QrCode.Internal.ErrorCorrectionLevel.H);

            writer.Options.Height = writer.Options.Width = codeSizeInPixels;
            writer.Options.Margin = 0;//设置边框1            ZXing.Common.BitMatrix bm = writer.Encode(msg);
            Bitmap img = writer.Write(msg);
            return img;
        }

    }

 

            Bitmap b = QRcode.GenByZXingNet("二维码内容字符串");
            MemoryStream ms = new MemoryStream();
            b.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
            byte[] bytes = ms.GetBuffer();
            string textString = System.Convert.ToBase64String(bytes);//存DBd的字符串
            ms.Close();

　　

string ImgString;//存DB的字符串
byte[] arrBuffer = System.Convert.FromBase64String(ImgString);//转换成文件流

　　页面上展示

                    <img src="data:image/jpeg;base64,{{Data.ImgString}}">

　　我上面是后端的写法，现在用下面的写法比较简单

使用jquery.qrcode生成二维码

 https://www.cnblogs.com/zhengweijie/p/6911834.html