下面这篇文章总结的很好：
Thymeleaf 标准表达式语法详解
https://blog.csdn.net/const_/article/details/97385319?spm=1001.2101.3001.6650.3&utm_medium=distribute.pc_relevant.none-task-blog-2%7Edefault%7ECTRLIST%7ERate-3.pc_relevant_antiscanv2&depth_1-utm_source=distribute.pc_relevant.none-task-blog-2%7Edefault%7ECTRLIST%7ERate-3.pc_relevant_antiscanv2&utm_relevant_index=5
