记得第一次安装jdk，按照教程配置环境变量，觉得环境变量是高深莫测的东西。

https://www.cnblogs.com/itren/p/3677838.html

https://blog.csdn.net/dingzi66/article/details/104821867

https://jingyan.baidu.com/article/4ae03de3afdc1c3eff9e6bfa.html