Log4j报错：
log4j:ERROR Failed to rename [/log/xxx.log] to [/log/xxx.log.2016-11-23.log]
google了一下发现是个bug：
https://bz.apache.org/bugzilla/show_bug.cgi?id=29726
I checked myself, and found it was solved only in 1.3 for DRFA.
For RFA, it has been solved in 1.2.15 too (see bug 41735). On another hand, now 1.3 has been abandoned. But its
o.a.l.rolling.RollingFileAppender, that solved the problem,
is available in companions / extras, which release 1.0 has
been recently released. Please note that, though RFA and DRFA are deprecated in favor
or o.a.l.rolling.RFA in 1.3, they are not deprecated in 1.2.15.
解决方法：升级log4j: 1.2.14到1.2.15。
发现另一个项目使用的是1.2.17 ，没有这个问题，应该从 1.2.15之后都fix了这个bug。