ThoughtWorks.QRCode

ThoughtWorks.QRCode.dll自行去nuget上下载安装

链接：https://pan.baidu.com/s/1dFKQh5nLYF61hvgxn2jI0Q

提取码：btlf 

var base64String = GetBase64String("");

HTML中使用：<img src="data:image/jpeg;base64,<%=base64String  %>" />