How to reload a programmed log4j2 configuration in java

Solution:

import java.nio.file.Paths; import org.apache.logging.log4j.Level; import org.apache.logging.log4j.LogManager; import org.apache.logging.log4j.Logger; import org.apache.logging.log4j.core.Appender; import org.apache.logging.log4j.core.LoggerContext; import org.apache.logging.log4j.core.config.Configuration; import org.apache.logging.log4j.core.config.LoggerConfig; public class Log4j2Init { private String logPath; // ------------------------------------------------------- // CONSTRUCTOR // ------------------------------------------------------- /** * Initialize Log4j2 * Configure log path which will be used in "log4j2.xml" * Common error is caused by the static logger * If you logs before the System.setProperty, this will cause the variable UNDEFINED error. * private static final Logger logger = LogManager.getLogger(test.class.getName()); * is forbidden here !! */ public Log4j2Init() { logPath = Paths.get(getUserAppDirectory()+"/Pac-Tool").toString(); System.setProperty("logpath.name",logPath); } // ------------------------------------------------------- // TEST // ------------------------------------------------------- public static void main(String[] args) { Log4j2Init log4j2Init = new Log4j2Init(); System.out.println("Pat of the Log File : " + log4j2Init.getLogPath()); // Create the Logger Logger logger = LogManager.getLogger(Log4j2Init.class.getName()); @SuppressWarnings("resource") LoggerContext ctx = (LoggerContext) LogManager.getContext(false); Configuration config = ctx.getConfiguration(); LoggerConfig loggerConfig = config.getLoggerConfig(LogManager.ROOT_LOGGER_NAME); // Read the Appenders System.out.println("Appenders declared in .xml :" + loggerConfig.getAppenderRefs()); System.out.println("Appenders used in Logger :" + loggerConfig.getAppenders()); // Apply the level specified in log4j2.xml System.out.println("Log Level (default in .xml)= " + loggerConfig.getLevel()); logger.error("This is Logger for 1 Error"); logger.info("This is Logger for 1 Info"); logger.debug("This is Logger for 1 Debug"); logger.trace("This is Logger for 1 Trace"); // Remove Console Logger + Set new log level loggerConfig.removeAppender("Console"); loggerConfig.setLevel(Level.TRACE); ctx.updateLoggers(); System.out.println("Log Level = " + loggerConfig.getLevel()); System.out.println("Appenders used in Logger :" + loggerConfig.getAppenders()); logger.error("This is Logger 2 Error"); logger.info("This is Logger 2 Info"); logger.debug("This is Logger 2 Debug"); logger.trace("This is Logger 2 Trace"); // Add Appender Appender appender = config.getAppender("Console"); loggerConfig.addAppender(appender, Level.TRACE, null ); ctx.updateLoggers(); System.out.println("Log Level = " + loggerConfig.getLevel()); System.out.println("Appenders used in Logger :" + loggerConfig.getAppenders()); logger.error("This is Logger 3 Error"); logger.info("This is Logger 3 Info"); logger.debug("This is Logger 3 Debug"); logger.trace("This is Logger 3 Trace"); } /** * getUserAppDirectory * @return */ private String getUserAppDirectory() { String workingDirectory; String OS = (System.getProperty("os.name")).toUpperCase(); if (OS.contains("WIN")) { //it is simply the location of the "AppData" folder workingDirectory = System.getenv("AppData"); } else { //Otherwise, we assume Linux or Mac workingDirectory = System.getProperty("user.home"); //if we are on a Mac, we are not done, we look for "Application Support" workingDirectory += "/Library/Application Support"; } return workingDirectory; } public String getLogPath() { return logPath; } 

}

With .xml

<?xml version="1.0" encoding="UTF-8"?> <!-- status will define the configuration level of log4j2 configuration file --> <Configuration status="error" name="XMLPACTOOL"> <Appenders> <!-- Generate Log in console --> <Console name="Console" target="SYSTEM_OUT"> <PatternLayout pattern="%d{HH:mm:ss.SSS} %-5level %logger{36} - %msg%n" /> </Console> <!-- Generate Log in file --> <File name="LogFile" fileName="${sys:logpath.name}/Pac-Tool.log" immediateFlush="false" append="false"> <PatternLayout pattern="%d{yyy-MM-dd HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n" /> </File> </Appenders> <Loggers> <Root level="info"> <AppenderRef ref="Console" /> <AppenderRef ref="LogFile" /> </Root> </Loggers> </Configuration>