log4j2 Logger 계층 Test

20 May 2019

Reading time ~3 minutes

log4j2.xml

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">
  <Appenders>
    <Console name="Console" target="SYSTEM_OUT">
      <PatternLayout pattern="Console %d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
    </Console>
    <Console name="ConsoleSubOne" target="SYSTEM_OUT">
      <PatternLayout pattern="ConsoleSubOne %d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
    </Console>
    <Console name="ConsoleSubTwo" target="SYSTEM_OUT">
      <PatternLayout pattern="ConsoleSubTwo %d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
    </Console>
    <Console name="RootConsole" target="SYSTEM_OUT">
      <PatternLayout pattern="RootConsole %d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
    </Console>
  </Appenders>
  <Loggers>
  	<Logger name="com.junseok.blog" level="debug" additivity="false">
  		<AppenderRef ref="Console"/>
  	</Logger>
  	<Logger name="com.junseok.blog.MyAppSubOne" level="info" additivity="false">
  		<AppenderRef ref="ConsoleSubOne"/>
  	</Logger>
  	<Logger name="com.junseok.blog.MyAppSubTwo" level="warn" additivity="false">
  		<AppenderRef ref="ConsoleSubTwo"/>
  	</Logger>
    <Root level="error">
      <AppenderRef ref="RootConsole"/>
    </Root>
  </Loggers>
</Configuration>

java 파일

package com.junseok.blog;

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

import com.junseok.logging.OtherLogging;

public class MyApp {

	private static final Logger logger = LogManager.getLogger(MyApp.class);

	private static MyAppSubOne subOne = new MyAppSubOne();
	private static MyAppSubTwo subTwo = new MyAppSubTwo();
	private static OtherLogging otherLogging = new OtherLogging();


	public static void main(String[] args) {

        logger.trace("MyApp TRACE log");
        logger.debug("MyApp DEBUG log");
        logger.info("MyApp INFO log");
        logger.warn("MyApp WARN log");
        logger.error("MyApp ERROR log");
        logger.fatal("MyApp FATAL log");

        subOne.doLogging();
        subTwo.doLogging();
        otherLogging.doLogging();
	}
}

//----------------------------------------------------------------------

package com.junseok.blog;

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

public class MyAppSubOne {

	private static final Logger logger = LogManager.getLogger(MyAppSubOne.class);

	public void doLogging() {

        logger.trace("MyAppSubOne TRACE log");
        logger.debug("MyAppSubOne DEBUG log");
        logger.info("MyAppSubOne INFO log");
        logger.warn("MyAppSubOne WARN log");
        logger.error("MyAppSubOne ERROR log");
        logger.fatal("MyAppSubOne FATAL log");
	}
}

//----------------------------------------------------------------------

package com.junseok.blog;

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

public class MyAppSubTwo {

	static final Logger logger = LogManager.getLogger(MyAppSubTwo.class.getName());

	public void doLogging() {

        logger.trace("MyAppSubTwo TRACE log");
        logger.debug("MyAppSubTwo DEBUG log");
        logger.info("MyAppSubTwo INFO log");
        logger.warn("MyAppSubTwo WARN log");
        logger.error("MyAppSubTwo ERROR log");
        logger.fatal("MyAppSubTwo FATAL log");
	}
}

//----------------------------------------------------------------------

package com.junseok.logging;

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

public class OtherLogging {

	private static final Logger logger = LogManager.getLogger(OtherLogging.class);

	public void doLogging() {

        logger.trace("OtherLogging TRACE log");
        logger.debug("OtherLogging DEBUG log");
        logger.info("OtherLogging INFO log");
        logger.warn("OtherLogging WARN log");
        logger.error("OtherLogging ERROR log");
        logger.fatal("OtherLogging FATAL log");
	}
}

output

Console 21:48:41.872 [main] DEBUG com.junseok.blog.MyApp - MyApp DEBUG log
Console 21:48:41.877 [main] INFO  com.junseok.blog.MyApp - MyApp INFO log
Console 21:48:41.878 [main] WARN  com.junseok.blog.MyApp - MyApp WARN log
Console 21:48:41.878 [main] ERROR com.junseok.blog.MyApp - MyApp ERROR log
Console 21:48:41.878 [main] FATAL com.junseok.blog.MyApp - MyApp FATAL log
ConsoleSubOne 21:48:41.878 [main] INFO  com.junseok.blog.MyAppSubOne - MyAppSubOne INFO log
ConsoleSubOne 21:48:41.878 [main] WARN  com.junseok.blog.MyAppSubOne - MyAppSubOne WARN log
ConsoleSubOne 21:48:41.878 [main] ERROR com.junseok.blog.MyAppSubOne - MyAppSubOne ERROR log
ConsoleSubOne 21:48:41.878 [main] FATAL com.junseok.blog.MyAppSubOne - MyAppSubOne FATAL log
ConsoleSubTwo 21:48:41.878 [main] WARN  com.junseok.blog.MyAppSubTwo - MyAppSubTwo WARN log
ConsoleSubTwo 21:48:41.878 [main] ERROR com.junseok.blog.MyAppSubTwo - MyAppSubTwo ERROR log
ConsoleSubTwo 21:48:41.878 [main] FATAL com.junseok.blog.MyAppSubTwo - MyAppSubTwo FATAL log
RootConsole 21:48:41.878 [main] ERROR com.junseok.logging.OtherLogging - OtherLogging ERROR log
RootConsole 21:48:41.878 [main] FATAL com.junseok.logging.OtherLogging - OtherLogging FATAL log

log4j2.xml 에 Logger name에 속하지 않은 클래스의 경우는 Root Logger 가 찍힙니다.
com.junseok.blog 로거와 com.junseok.blog.MyAppSubOne 이 있는 경우 더 상세한 로거를 찾고 해당 로거에 속하지 않으면 부모 로거를 찾습니다.
자식: com.junseok.blog.MyAppSubOne 부모: com.junseok.blog
한마디로 자식 로거 에 속하지 않으면 부모 로거 를 찾고 부모 로거 또한 없으면 Root Logger 를 사용합니다.

getLogger(…) 로거를 가져오는 방법.

파라미터를 넘기지 않는 경우
호출 측의 클래스 명을 가지는 Logger 를 돌려줍니다.
Class 파라미터 를 넘기는 경우
클래스의 완전 수식 명을 Logger 명의로서 사용 해, Logger를 돌려줍니다.
String 파라미터 를 넘기는 경우
지정된 이름을 가지는 Logger 를 돌려줍니다.

Root Logger 를 얻는 방법

private static final Logger logger = LogManager.getLogger(MyApp.class);
// or
private static final Logger logger = LogManager.getRootLogger();