mybatis – MyBatis 3 | Logging
https://mybatis.org/mybatis-3/logging.html
log4j - Logging Levels - Tutorialspoint
https://www.tutorialspoint.com/log4j/log4j_logging_levels.htm
How do Levels Works?
A log request of level p in a logger with level q is enabled if p >= q. This rule is at the heart of log4j. It assumes that levels are ordered. For the standard levels, we have ALL < DEBUG < INFO < WARN < ERROR < FATAL < OFF.
mybatis结合log4j打印SQL日志 - zhchoutai - 博客园
https://www.cnblogs.com/zhchoutai/p/7252184.html
org.apache.log4j.Logger详解 - 山高我为峰 - 博客园
https://www.cnblogs.com/liaojie970/p/7634838.html