使用 SLF4J

Simple Logging Facade for Java (SLF4J)
So long, commons-logging, hello SLF4J
Logback Project

SLF4J 預設使用 Logback，需要下列 package
  slf4j-api-*.jar
  logback-classic-*.jar
  logback-core-*.jar

若要使用 LOG4j 則使用下列 package
  slf4j-api-*.jar
  slf4j-log4j12-*.jar
  log4j-*.jar

Main.java

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class Main {
 
 private final Logger logger = LoggerFactory.getLogger(Main.class);
 
 public Main() {
  logger.debug("Constructor {}", new java.util.Date());
 }
 
 public static void main(String[] args) {
  Main main = new Main();
 }

}