JUL Adapter not working for Jersey

Question

I am trying to use JUL Adapter to delegate Java Util Logging to Log4j2. More precisely, any third-party library that use JUL to generate logs, should be delegat

Answer 1

If you are not able or allowed to change the configuration of the container, here's an alternative solution that worked for me.

When the context is initialised, remove all the handlers that a JUL logger has, then add your own custom handler where you can use your preferred logging framework.

Here's an example:

import java.util.logging.Handler;
import java.util.logging.LogRecord;
import java.util.logging.Logger;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;

import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.LogManager;

@WebListener
public class ContextInitializer implements ServletContextListener {

    Logger logger = Logger.getLogger("");
    static final org.apache.logging.log4j.Logger log4jLogger = LogManager.getLogger();

    @Override
    public void contextInitialized(ServletContextEvent sce) {
        for (Handler hanlder : logger.getHandlers()) {
            logger.removeHandler(hanlder);
        }
        logger.addHandler(new CustomHandler());
    }

    @Override
    public void contextDestroyed(ServletContextEvent sce) {
        System.out.println("Context destroyed.");
    }

    private static class CustomHandler extends Handler {

        @Override
        public void publish(LogRecord record) {
            log4jLogger.log(CustomHandler.julToLog4jLevel(record.getLevel()), record.getMessage(), record.getThrown());
        }

        /**
         * Converts the logging level according to [default level conversions](https://logging.apache.org/log4j/2.0/log4j-jul/index.html)
         */
        private static Level julToLog4jLevel(java.util.logging.Level level) {
            if (level == java.util.logging.Level.WARNING) {
                return Level.WARN;
            } else if (level == java.util.logging.Level.SEVERE) {
                return Level.ERROR;
            } else if (level == java.util.logging.Level.INFO) {
                return Level.INFO;
            } else if (level == java.util.logging.Level.FINE) {
                return Level.DEBUG;
            } else if (level == java.util.logging.Level.FINER) {
                return Level.TRACE;
            } else if (level == java.util.logging.Level.FINEST) {
                return Level.ALL;
            }

            return null;
        }

        @Override
        public void flush() {

        }

        @Override
        public void close() throws SecurityException {

        }
    }
}