https://stackoverflow.com/questions/734963/log4net-rollingfileappender-with-composite-rolling-style-is-overwritting-data
I want it to roll on just the date. By default, though, the rolling is set to composite, so it rolls on date or size, whichever comes first.
rollingstyle in log4net
原文：https://www.cnblogs.com/chucklu/p/10207163.html
