log4j.rootLogger
Log4j recommends using only four levels, the priority from high to low is ERROR, WARN, INFO, DEBUG. With the level defined here, you can control the switch to the corresponding level of log information in the application.
For example, if the INFO level is defined here, all DEBUG level log information in the application will not be printed.The program will print logs higher than or equal to the set level. The higher the set log level, the less logs will be printed.
If the setting level is INFO, the log information with priority higher than or equal to the INFO level (such as: INFO, WARN,
ERROR) will be output, and the log information with a priority lower than this level, such as DEBUG, will not be output.