使用开源类库ZXing.dll可以在C#中生成二维码和解析二维码为指定的字符串（含url）

新建windows窗体应用程序QRCodeDemo，.net 4.5,将默认的Form1重命名为FormQuickResponseCode。

添加对开源类库zxing.dll和zxing.presentation.dll的引用，用于解析和生成条码【一维条码、二维条码均可生成】。

窗体FormQuickResponseCode设计器如下：

新建读写二维码类QrCodeUtil，QrCodeUtil.cs源程序如下：

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using ZXing;
using ZXing.QrCode;
using ZXing.QrCode.Internal;
 
namespace QRCodeDemo
{
    /// <summary>
    /// 文本字符串与二维码图片之间的转换
    /// 字符串转二维码 String---->Image
    /// 二维码转字符串 Image---->String
    /// </summary>
    public class QrCodeUtil
    {
        /// <summary>
        /// 将文本字符串转化为二维码图片
        /// </summary>
        /// <param name="codeContent">打印条码对应的字符串</param>
        /// <param name="width"></param>
        /// <param name="height"></param>
        /// <param name="barcodeFormat">条码格式：CODE_128代表一维条码，QR_CODE代表二维码</param>
        /// <param name="margin"></param>
        /// <returns></returns>
        public static Bitmap GeneateQrCode(string codeContent, int width, int height, BarcodeFormat barcodeFormat, string errorCorrectionLevel, int margin = 1)
        {
            // 1.设置QR二维码的规格
            QrCodeEncodingOptions qrEncodeOption = new QrCodeEncodingOptions();
            qrEncodeOption.ErrorCorrection = GetErrorCorrectionLevel(errorCorrectionLevel);
            qrEncodeOption.DisableECI = true;
            qrEncodeOption.CharacterSet = "UTF-8"; // 设置编码格式，否则读取'中文'乱码
            qrEncodeOption.Height = height;
            qrEncodeOption.Width = width;
            qrEncodeOption.Margin = margin; // 设置周围空白边距
            qrEncodeOption.PureBarcode = true;
            //System.Windows.Forms.MessageBox.Show("" + qrEncodeOption.ErrorCorrection.Name + "...." + qrEncodeOption.ErrorCorrection.Bits);
            // 2.生成条形码图片
            BarcodeWriter wr = new BarcodeWriter();
            wr.Format = barcodeFormat; // 二维码 BarcodeFormat.QR_CODE
            wr.Options = qrEncodeOption;
            Bitmap img = wr.Write(codeContent);
            return img; 
        }
 
        /// <summary>
        /// 解码二维码,返回一个文本字符串，如果返回为null，则解析(转化)失败
        /// </summary>
        /// <param name="barcodeBitmap">待解码的二维码图片</param>
        /// <returns>扫码结果</returns>
        public static string DecodeQrCode(Bitmap barcodeBitmap)
        {
            BarcodeReader reader = new BarcodeReader();
            reader.Options.CharacterSet = "UTF-8";
            Result result = reader.Decode(barcodeBitmap);
            return (result == null) ? null : result.Text;
        }
 
        /// <summary>
        /// 获取纠错级别
        /// </summary>
        /// <param name="name"></param>
        /// <returns></returns>
        private static ErrorCorrectionLevel GetErrorCorrectionLevel(string levelName)
        {
            switch (levelName)
            {
                case "L"://bits=1
                    return ErrorCorrectionLevel.L;
                case "M"://bits=0
                    return ErrorCorrectionLevel.M;
                case "Q"://bits=3
                    return ErrorCorrectionLevel.Q;
                case "H"://bits=2
                    return ErrorCorrectionLevel.H;
                default:
                    return ErrorCorrectionLevel.M;
            }
        }
    }
}

窗体FormQuickResponseCode 主要程序如下（忽略设计器自动生成的代码）：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
 
namespace QRCodeDemo
{
    public partial class FormQuickResponseCode : Form
    {
        public FormQuickResponseCode()
        {
            InitializeComponent();
            //矩阵二维码QRCode： Quick Response Code            
 
            rtxtCodeMessage.Text = "https://blog.csdn.net/ylq1045\n斯内科";
            this.cboImageFormat.Items.AddRange(new object[] {
            "GIF",
            "JPG/JPEG",
            "PNG",
            "BMP"});
            this.cboErrorCorrectionLevel.Items.AddRange(new object[] {
            "L  7%",
            "M 15%",
            "Q 25%",
            "H 30%"});
 
            cboImageFormat.SelectedIndex = 1;
            cboErrorCorrectionLevel.SelectedIndex = 1;
        }
 
        private void btnGenerateQR_Click(object sender, EventArgs e)
        {
            if (rtxtCodeMessage.Text.Length == 0)
            {
                MessageBox.Show("请输入URL或者文本字符串", "提示");
                return;
            }
            string errorCorrectionLevel = "M";
            if (cboErrorCorrectionLevel.Text.Length > 0)
            {
                errorCorrectionLevel = cboErrorCorrectionLevel.Text.Substring(0, 1);
            }
            Bitmap bitmap = QrCodeUtil.GeneateQrCode(rtxtCodeMessage.Text, 200, 200, ZXing.BarcodeFormat.QR_CODE,errorCorrectionLevel);
            pictureBox1.SizeMode = PictureBoxSizeMode.CenterImage;
            pictureBox1.Image = bitmap;
        }
 
        private void btnExport_Click(object sender, EventArgs e)
        {
            SaveFileDialog saveImageDialog = new SaveFileDialog();
            saveImageDialog.Title = "图片保存";
            switch (cboImageFormat.Text)
            {
                case "GIF":
                    saveImageDialog.Filter = "gif|*.gif|All|*.*";
                    break;
                case "JPG/JPEG":
                    saveImageDialog.Filter = "jpeg|*.jpg|All|*.*";
                    break;
                case "PNG":
                    saveImageDialog.Filter = "png|*.png|All|*.*";
                    break;
                case "BMP":
                    saveImageDialog.Filter = "bmp|*.bmp|All|*.*";
                    break;
                default:
                    saveImageDialog.Filter = "jpeg|*.jpg|bmp|*.bmp|gif|*.gif|png|*.png|All|*.*";
                    break;
            }
            if (saveImageDialog.ShowDialog() == DialogResult.OK)
            {
                System.Drawing.Imaging.ImageFormat imgformat = GetImageFormat(cboImageFormat.Text);
                string fileName = saveImageDialog.FileName;
                try
                {
                    pictureBox1.Image.Save(fileName, imgformat);
                    MessageBox.Show($"导出成功，图片文件路径：\n{fileName}", "导出文件");
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message, "导出文件出错");
                }
            }
        }
 
        private void btnOpenFile_Click(object sender, EventArgs e)
        {
            OpenFileDialog openFileDialog = new OpenFileDialog();
            openFileDialog.Filter= "jpeg|*.jpg|bmp|*.bmp|gif|*.gif|png|*.png|All|*.*";
            if (openFileDialog.ShowDialog() == DialogResult.OK)
            {
                string fileName = openFileDialog.FileName;
                try
                {
                    pictureBox1.SizeMode = PictureBoxSizeMode.CenterImage;
                    pictureBox1.Image = Image.FromFile(fileName);
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message, "打开图像文件出错");
                }
            }
        }
 
        private void btnDiscern_Click(object sender, EventArgs e)
        {
            rtxtCodeMessage.Clear();
            try
            {
                string codeMessage = QrCodeUtil.DecodeQrCode(new Bitmap(pictureBox1.Image));
                if (string.IsNullOrEmpty(codeMessage))
                {
                    MessageBox.Show($"识别二维码图片出错,可能不是二维码图片格式，或者过于模糊，\n请打开新的二维码图片重新尝试", "识别二维码图片出错");
                    return;
                }
                rtxtCodeMessage.Text = codeMessage;
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "识别二维码图片出错");
            }
        }
 
        /// <summary>
        /// 获取图像文件格式
        /// </summary>
        /// <param name="formatName"></param>
        /// <returns></returns>
        private System.Drawing.Imaging.ImageFormat GetImageFormat(string formatName)
        {
            switch (formatName)
            {
                case "GIF":
                    return System.Drawing.Imaging.ImageFormat.Gif;
                case "JPG/JPEG":
                    return System.Drawing.Imaging.ImageFormat.Jpeg;
                case "PNG":
                    return System.Drawing.Imaging.ImageFormat.Png;
                case "BMP":
                    return System.Drawing.Imaging.ImageFormat.Bmp;
                default:
                    return System.Drawing.Imaging.ImageFormat.Jpeg;
            }
        }
    }
}