Log4JIt’s an open source project organized by Apache that uses Log4J to specify the destination of log information output, such as console, file, and so on. Log4J uses the log level mechanism, and write out the log output levels in the order from low to high output levels.
Answer: Log4J is divided into OFF, FATAL, ERROR, WARN, INFO, DEBUG, ALL, or the level you define. Log4j recommends that only four levels be used, and the priority ranges from high to low are ERROR, WARN, INFO and DEB.UG. By defining the level here, you can control the switch to log information at the appropriate level in the application. For example, if the INFO level is defined here, all DEBUG level log information in the application will not be printed.