Redirecting Java Util Logging (JUL) to SLF4j + Log4j with jul-to-slf4j bridge

This example shows how to bridge Java Util Logging (JUL) logs to SLF4J. We are going to use Log4J as SLF4J implementation provider. That means all log messages send via JUL API will redirect to SLF4J layer which will then use Log4J as implementation provider to output the messages.

Dependencies

pom.xml

<dependency>
   <groupId>org.slf4j</groupId>
   <artifactId>jul-to-slf4j</artifactId>
   <version>1.8.0-alpha2</version>
</dependency>
<dependency>
   <groupId>org.slf4j</groupId>
   <artifactId>slf4j-log4j12</artifactId>
   <version>1.8.0-alpha2</version>
</dependency>

Using JUL API

package com.logicbig.example;

import java.util.logging.Logger;

public class MyClass {

  private static Logger LOGGER = Logger.getLogger(MyClass.class.getName());

  public static void doSomething() {
      LOGGER.info("a test message");
  }
}

Log4j configuration

src/main/resources/log4j.properties

log4j.rootCategory=INFO, stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{yyyy-MMMM-dd HH:mm:ss:SSS} %5p %t %c{2}:%L - %m%n

Enabling the bridge

package com.logicbig.example;

import org.slf4j.bridge.SLF4JBridgeHandler;

import java.util.logging.LogManager;

public class ExampleMain {
  static {
      LogManager.getLogManager().reset();
      SLF4JBridgeHandler.install();
  }

  public static void main(String[] args) {
      MyClass.doSomething();
  }
}

Output

2017-September-11 12:49:12:136  INFO com.logicbig.example.ExampleMain.main() example.MyClass:10 - a test message

In above main class we installed SLF4JBridgeHandler, which is an implementation of java.util.logging.Handler. Check out this tutorial to have an understanding of JUL Handler.

Example Project

Dependencies and Technologies Used:

• jul-to-slf4j 1.8.0-alpha2: JUL to SLF4J bridge.
• slf4j-log4j12 1.8.0-alpha2: SLF4J LOG4J-12 Binding.
• JDK 1.8
• Maven 3.3.9