https://www.liaoxuefeng.com/wiki/1022910821149312/1023022494381696 //引入
https://developer.mozilla.org/zh-CN/docs/Web/HTML/Element/Input/file //细节讲解文档
https://www.haorooms.com/post/input_file_leixing //常用MIME类型
https://www.w3school.com.cn/tags/att_label_for.asp //label 的for 绑定
https://www.cnblogs.com/fozero/p/8835628.html //实例
https://www.jianshu.com/p/134473c8d162 //实例
原文：https://www.cnblogs.com/Spring-Rain/p/11964388.html