动态更改日志记录级别

Question

I want to change the level of logging for all (about) of my web application controller classes dynamically. Each class that does logging contains this code:

private static final Logger logger = LoggerFactory
            .getLogger(HomeController.class);

I learned that slf4j doesn't offer the functionality of setting a log level, so that one has to use the underlying log4j:

public static void setLogLevel(String level) {
    org.apache.log4j.Logger logger4j = org.apache.log4j.Logger.getRootLogger();
    logger4j.setLevel(org.apache.log4j.Level.toLevel(level.toUpperCase()));

    logger.info("Sample Info After setLevel");
    logger.debug("Sample Debug After setLevel");
    logger.error("Sample Error After setLevel");
    logger.trace("Sample Trace After setLevel");
    logger.warn("Sample Warn After setLevel");
}

My idea is to have a controller method which changes the logLevel and maybe stores it in the database. My question is: How I can solve this elegantly without copy and pasting everything in 40+ files and modifying every controller method? Also note that the logger code is static, while my database access is not static.

Answer 1

How I can solve this elegantly without copy and pasting everything in 40+ files and modifying every controller method?

You use a single controller method, taking the logger name and desired log level as a query parameters, and call the string version of LogManager.getLogger(String name) .

Also saving to the database and re-loading on restart is of course extra work to be done by you.

Alternatively, the controller can update the Log4j configuration file used at startup, and force Log4j to reload it whenever it's changed, eg by calling PropertyConfigurator.configure(String configFilename) .

Answer 2

You can use Slf4j and externalize your application.properties file . You can configure the logging level in this file as per your needs.

logging.level.com.test=DEBUG
logging.level.org=INFO

I am not sure why you need to store this logging level in the Database.