https://blog.wongcw.com/2018/10/12/typecho%e8%8e%b7%e5%8f%96%e7%94%a8%e6%88%b7ua%e5%ae%9e%e7%8e%b0%e6%96%b9%e6%b3%95/
typecho获取用户UA实现方法