Referencing java class variable from log4j2.xml configuration

You have at least the following choices:

1. Use an environment variable, like: <PatternLayout pattern="${env:MY_PATTERN}" />. And define the variable before the logger is initialized, with: System.setProperty("MY_PATTERN",PatternLayout.SIMPLE_CONVERSION_PATTERN).

2. Or, if you need the pattern to be defined at runtime based on some conditions, you can define your own Logger class with a custom appender, something like (this is using the file appender, but you will get the idea):

   public class MyLogClass { private static Logger log = Logger.getLogger(MyLogClass.class); private static boolean initFlag = false; private static void initLogger(){ log.setLevel(Level.DEBUG); DateFormat dateFormat = new SimpleDateFormat("dd/MM/yyyy HH:mm:ss"); Date date = new Date(); RollingFileAppender appender = new RollingFileAppender(); appender.setAppend(true); appender.setMaxFileSize("1MB"); appender.setMaxBackupIndex(1); appender.setFile("my_log_file-" + dateFormat.format(date) + ".log"); PatternLayout layOut = new PatternLayout(); layOut.setConversionPattern(PatternLayout.SIMPLE_CONVERSION_PATTERN); appender.setLayout(layOut); log.addAppender(appender); } public static Logger getLogger(){ if(initFlag == false){ initLogger(); initFlag = true; return MyLogClass.log; } else { return MyLogClass.log; } } } 

Then use it like:

LogClass.getLogger().debug("test");