.NET--二维码

1. 从Nuget上找到这一个程序包（这个程序包兼容.net framework 4.7和.net core，之前引用过其他的程序包，发现并不兼容.net framework 4.7）

1. 我重载了一个方法GenerateQRCode，用于生成带文字说明和不带文字说明的二维码。不带文字说明的二维码大小尺寸没有加限制，返回的是原始大小，带文字说明的二维码大小限制为了600*600px（包括文字，可以根据需要自行调整），同时，我将二维码的文字说明放在了二维码的下面（当然了，文字位置也是可以自行调整的，后续有时间我会继续补充）

using QRCoder;
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace App.Common.QRCode
{
    /// <summary>
    /// 二维码帮助类
    /// </summary>
    public class QRCodeHelper
    {
        /// <summary>
        /// 生成二维码图片
        /// </summary>
        /// <param name="str"></param>
        /// <returns></returns>
        public Bitmap CreateQRimg(string str)
        {
            QRCodeGenerator qrGenerator = new QRCodeGenerator();
            QRCodeData qrCodeData = qrGenerator.CreateQrCode(str, QRCodeGenerator.ECCLevel.Q);
            QRCoder.QRCode qrCode = new QRCoder.QRCode(qrCodeData);
            Bitmap bt = qrCode.GetGraphic(20);
            return bt;
        }
        /// <summary>
        /// 生成二维码图片流（二维码上含文字）
        /// </summary>
        /// <param name="str1">二维码中要传递的数据（地址）</param>
        /// <param name="str2">二维码上显示的文字说明</param>
        public byte[] GenerateQRCode(string str1, string str2)
        {
            using (Image codeImage = CreateQRimg(str1), strImage = ConvertStringToImage(str2))
            {
                Image img = CombineImage(600, 600, codeImage, 60, 50, strImage, 0, 530);
                using (var stream = new MemoryStream())
                {
                    img.Save(stream, ImageFormat.Jpeg);
                    //输出图片流
                    return stream.ToArray();
                }
            }
        }
        /// <summary>
        /// 生成二维码图片流（不含文字）
        /// </summary>
        /// <param name="str">二维码中要传递的数据（地址）</param>
        /// <returns></returns>
        public byte[] GenerateQRCode(string str)
        {
            using (Image codeImage = CreateQRimg(str))
            {
                using (var stream = new MemoryStream())
                {
                    codeImage.Save(stream, ImageFormat.Jpeg);
                    return stream.ToArray();
                }
            }
        }
        /// <summary>
        /// 生成文字图片
        /// </summary>
        /// <param name="str"></param>
        /// <returns></returns>
        public Image ConvertStringToImage(string str)
        {
            Bitmap image = new Bitmap(600, 40, PixelFormat.Format24bppRgb);
            Graphics g = Graphics.FromImage(image);
            try
            {
                Font font = new Font("SimHei", 14, FontStyle.Regular);
                g.Clear(Color.White);
                StringFormat format = new StringFormat();
                format.Alignment = StringAlignment.Center;
                format.LineAlignment = StringAlignment.Center;
                Rectangle rectangle = new Rectangle(0, 0, 600, 40);
                g.DrawString(str, font, new SolidBrush(Color.Black), rectangle, format);
                return image;
            }
            catch (Exception e)
            {
                throw e;
            }
            finally
            {
                GC.Collect();
            }
        }
        /// <summary>
        /// 在画板中合并二维码图片和文字图片
        /// </summary>
        /// <param name="width"></param>
        /// <param name="height"></param>
        /// <param name="imgLeft"></param>
        /// <param name="imgLeft_left"></param>
        /// <param name="imgLeft_top"></param>
        /// <param name="imgRight"></param>
        /// <param name="imgRight_left"></param>
        /// <param name="imgRight_top"></param>
        /// <returns></returns>
        public Image CombineImage(int width, int height, Image imgLeft, int imgLeft_left, int imgLeft_top, Image imgRight, int imgRight_left, int imgRight_top)
        {
            Bitmap image = new Bitmap(width, height, PixelFormat.Format24bppRgb);
            Graphics g = Graphics.FromImage(image);
            try
            {
                g.Clear(Color.White);
                g.DrawImage(imgLeft, imgLeft_left, imgLeft_top, 500, 500);
                g.DrawImage(imgRight, imgRight_left, imgRight_top, imgRight.Width, imgRight.Height);
                return image;
            }
            catch (Exception e)
            {
                throw e;
            }
            finally
            {
                g.Dispose();
            }
        }
    }
}

1. 两个调用方法

MVC模式下调用

/// <summary>
/// Mvc
/// </summary>
public class QRCodeController : Controller
{
    /// <summary>
    /// 显示二维码
    /// </summary>
    /// <returns></returns>
    public ActionResult Index()
    {
         var qrCode = new QRCodeHelper();
         var qrImg = qrCode.GenerateQRCode("https://www.cnblogs.com/wenha");
         var base64 = "data:image/jpeg;base64," + Convert.ToBase64String(qrImg);
         ViewBag.CodeImg = base64;
         return View();
    }
}

WebApi模式下调用

/// <summary>
/// WebApi
/// </summary>
public class QRCodeApiController : ApiController
{
      /// <summary>
      /// 获取二维码图片（base64格式）
      /// </summary>
      /// <returns></returns>
     [HttpGet]
     public HttpResponseMessage GetQRCode()
     {
         var qrCode = new QRCodeHelper();
         var url = "https://www.cnblogs.com/wenha";
         var image = qrCode.GenerateQRCode(url, "博客园地址");
         var resp = new HttpResponseMessage(HttpStatusCode.OK)
         {
             Content = new StringContent("data:image/jpeg;base64," + Convert.ToBase64String(image))
         };
         return resp;
     }
     /// <summary>
     /// 获取二维码图片（图片格式）
     /// </summary>
     /// <returns></returns>
     [HttpGet]
     public HttpResponseMessage GetQRCodeImg()
     {
         var qrCode = new QRCodeHelper();
         var url = "https://www.cnblogs.com/wenha";
         var image = qrCode.GenerateQRCode(url, "博客园地址");
         var resp = new HttpResponseMessage(HttpStatusCode.OK)
         {
             Content = new ByteArrayContent(image)
         };
         resp.Content.Headers.ContentType = new MediaTypeHeaderValue("image/jpg");
         return resp;
     }
}

前端展示：

即将后端返回的base64格式的字符串放进 img标签，即可显示二维码。

<img style="width: 150px; height: 150px" src="image"/>

c#生成小程序二维码，扫描后跳转指定页面