Set Level for all java.util.logging Loggers programmatically

Question

I work on an application which uses slf4j and log4j2 as the underlying logging framework. The application provides custom logging filters, based on the current user of the application. Some third party libraries use java.util.logging (JUL) internally. I would like those logs to also submit to my user based filter. I.e. while the default log level may be ERROR, I can configure the application to log on level DEBUG when an specific user is using it.

Therefore I integrated the jul-to-slf4j bridge so that JUL logging is redirected to slf4j. I've also created a custom java.util.logging.Filter as described here which implements my user based filter logic.

Now my problem is that the default log level in JUL seems to be INFO and there also is logic which first checks if the message to log has an less fine level than the level of the logger, in which case the message is rejected immediatly without passing through the filter (in this case my custom filter). Because of this I want all JUL Loggers (also the ones used in third party libraries) to by default have the level ALL so that all JUL log statements would pass through my filter where it would be determined wether to log the message or to discard it.

I've tried setting the JULs root logger and it's handlers level to ALL as it is described in multiple posts here on SO, but this didn't seem to make the trick as seen here. It looks like I have to configure the JUL LogManager accordingly and I wonder if I can do so programatically without introducing a new log file?

Answer 1

From code you can reset all loggers using code like the following:

private static void resetLoggersToRoot() {
    Logger root = Logger.getLogger("");
    LogManager lm = LogManager.getLogManager();
    synchronized (lm) {
        Enumeration<String> e = lm.getLoggerNames();
        while (e.hasMoreElements()) {
            Logger l = lm.getLogger(e.nextElement());
            if (l != null && l != root) {
                l.setLevel(root.getLevel());
                l.setFilter(root.getFilter());
                l.setUseParentHandlers(root.getUseParentHandlers());
                for(Handler h : l.getHandlers()) {
                    l.removeHandler(h);
                }
            }
        }
    }
}

However, there is a issue where loggers are created on demand. Therefore you might have to call LogManager.getLogManager().reset(); to remove any existing configuration from a logging.properties file.