e395. setting the log level of a logger.txt

这里面包含了一百多个JAVA源文件

The log level of a logger controls the severity of messages that it will log. In particular, a log record whose severity is greater than or equal to the logger's log level is logged. 
A log level can be null, in which case the level is inherited from the logger's parent. 

Note: Logger handlers also have a log level. A log record must first pass the logger's log level before it is compared to the handler's log level. 

    // Get a logger
    Logger logger = Logger.getLogger("com.mycompany");
    
    // Set the level to a particular level
    logger.setLevel(Level.INFO);
    
    // Set the level to that of its parent
    logger.setLevel(null);
    
    // Turn off all logging
    logger.setLevel(Level.OFF);
    
    // Turn on all logging
    logger.setLevel(Level.ALL);