标签：ref post get tail 抽象 logs net class log
https://www.cnblogs.com/yongjiapei/p/5494894.html
http://blog.csdn.net/chengqiuming/article/details/70139323
接口和抽象类有什么区别
原文地址：https://www.cnblogs.com/feifeicui/p/8487238.html
