C# 生成二维码

 1、添加 ThoughtWorks.QRCode.dll 引用

 2、代码

1using System;
2using System.Collections.Generic;
3using System.Linq;
4using System.Threading.Tasks;
5using Microsoft.AspNetCore.Authorization;
6using Microsoft.AspNetCore.Cors;
7using Microsoft.AspNetCore.Mvc;
8using System.Drawing;
9using System.Text;
10using ThoughtWorks.QRCode.Codec;
11using System.IO;
12
13namespace App.Web.APIControllers
14{
15    /// <summary>
16    /// 生成二维码
17    /// </summary>    public class QRCodeController : Controller
18    {
19        /// <summary>
20        /// 生成二维码
21        /// </summary>
22        /// <param name="enCodeString">要生成二维码的文字</param>
23        /// <returns></returns>
24        [HttpGet]
25        [AllowAnonymous]
26        public string QRCode(string enCodeString)
27        {
28            System.Drawing.Bitmap bt;
29            QRCodeEncoder qrCodeEncoder = new QRCodeEncoder();
30            qrCodeEncoder.QRCodeEncodeMode = QRCodeEncoder.ENCODE_MODE.BYTE;//编码方式(注意：BYTE能支持中文，ALPHA_NUMERIC扫描出来的都是数字)
31            qrCodeEncoder.QRCodeScale = 10;//大小(值越大生成的二维码图片像素越高)
32            qrCodeEncoder.QRCodeVersion = 0;//版本(注意：设置为0主要是防止编码的字符串太长时发生错误)
33            qrCodeEncoder.QRCodeErrorCorrect = QRCodeEncoder.ERROR_CORRECTION.M;//错误效验、错误更正(有4个等级)
34            qrCodeEncoder.QRCodeBackgroundColor = Color.White;//背景色
35            qrCodeEncoder.QRCodeForegroundColor = Color.Black;//前景色
36            bt = qrCodeEncoder.Encode(enCodeString, Encoding.UTF8);
37            string filename = enCodeString;// "code";
38            string file_path = AppDomain.CurrentDomain.BaseDirectory + "QRCode\\";
39            string codeUrl = file_path + filename + ".jpg";
40
41            //根据文件名称，自动建立对应目录
42            if (!System.IO.Directory.Exists(file_path))
43            {
44                System.IO.Directory.CreateDirectory(file_path);
45            }
46            ////防止内容重复，导致名称重复问题，
47            ////若要每次更新，可去掉本段代码 ↓↓↓↓↓
48            //int i = 1;
49            //while (System.IO.File.Exists(codeUrl))
50            //{               
51            //    string _filename = filename + "("+i+")";
52            //    codeUrl = file_path + _filename + ".jpg";
53            //    i++;
54            //}
55            ////   ↑↑↑↑↑↑↑
56
57            bt.Save(codeUrl);//保存图片
58            return codeUrl;
59        }
60
61
62        /// <summary>
63        /// 生成二维码【方法二】
64        /// </summary>
65        /// <param name="qrCodeScale">尺寸4-15</param>
66        /// <param name="qrCodeVersion">复杂级别3-12</param>
67        /// <param name="qrCodeErrorCorrect">容错量"H","L","M","Q"</param>
68        /// <param name="enCodeString">二维码信息</param>        
69        /// <returns></returns>
70        [HttpGet]
71        [AllowAnonymous]
72        public  string CreateEQcoder(int qrCodeScale, int qrCodeVersion, string qrCodeErrorCorrect, string enCodeString)
73        {
74            QRCodeEncoder qrCodeEncoder = new QRCodeEncoder();
75            qrCodeEncoder.QRCodeEncodeMode = QRCodeEncoder.ENCODE_MODE.BYTE;
76            qrCodeEncoder.QRCodeScale = qrCodeScale;
77            qrCodeEncoder.QRCodeVersion = qrCodeVersion;
78            switch (qrCodeErrorCorrect)
79            {
80                case "H":
81                    qrCodeEncoder.QRCodeErrorCorrect = QRCodeEncoder.ERROR_CORRECTION.H;
82                    break;
83                case "L":
84                    qrCodeEncoder.QRCodeErrorCorrect = QRCodeEncoder.ERROR_CORRECTION.L;
85                    break;
86                case "M":
87                    qrCodeEncoder.QRCodeErrorCorrect = QRCodeEncoder.ERROR_CORRECTION.M;
88                    break;
89                case "Q":
90                    qrCodeEncoder.QRCodeErrorCorrect = QRCodeEncoder.ERROR_CORRECTION.Q;
91                    break;
92            }
93            qrCodeEncoder.QRCodeErrorCorrect = QRCodeEncoder.ERROR_CORRECTION.L;
94            Bitmap bmPhoto = qrCodeEncoder.Encode(enCodeString, System.Text.Encoding.GetEncoding("UTF-8"));
95            string fileName = enCodeString+"_"+ qrCodeScale+"_"+qrCodeVersion+"_"+ qrCodeErrorCorrect;
96            string file_path = AppDomain.CurrentDomain.BaseDirectory + "QRCode\\";
97            string savePath = file_path + fileName + ".jpg";
98            try
99            {
100                if (!Directory.Exists(file_path))
101                {
102                    Directory.CreateDirectory(file_path);
103                }
104
105                //防止内容重复，导致名称重复问题，若要每次更新，可去掉本段代码 ↓↓↓↓↓
106                int i = 1;
107                while (System.IO.File.Exists(savePath))
108                {
109                    string _filename = fileName + "(" + i + ")";
110                    savePath = file_path + _filename + ".jpg";
111                    i++;
112                }
113                //↑↑↑↑↑↑↑
114                bmPhoto.Save(savePath);
115                bmPhoto.Dispose();
116                return savePath ;
117            }
118            catch (Exception)
119            {
120                return "";
121            }
122            finally
123            {
124                bmPhoto.Dispose();
125            }
126        }
127    }
128}

 两种方法实际是一种方法。