Apache Log4j 2

Apache Log4j 2 is a versatile, feature-rich, efficient logging API and backend for Java.

Description

Apache Log4j 2 is an upgrade to Log4j that provides significant improvements over its predecessor, Log4j 1.x, and provides many of the improvements available in Logback while fixing some inherent problems in Logback's architecture.

Code Quality Rank: L3

Programming language: Java

License: Apache License 2.0

Tags: Logging    

Latest version: v2.13.3

README

<!--- Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

  http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. -->

Apache Log4j 2

Apache Log4j 2 is an upgrade to Log4j that provides significant improvements over its predecessor, Log4j 1.x, and provides many of the improvements available in Logback while fixing some inherent problems in Logback's architecture.

Pull Requests on Github

By sending a pull request you grant the Apache Software Foundation sufficient rights to use and release the submitted work under the Apache license. You grant the same rights (copyright license, patent license, etc.) to the Apache Software Foundation as if you have signed a Contributor License Agreement. For contributions that are judged to be non-trivial, you will be asked to actually signing a Contributor License Agreement.

Usage

Users should refer to Maven, Ivy, Gradle, and SBT Artifacts on the Log4j website for instructions on how to include Log4j into their project using their chosen build tool.

Basic usage of the Logger API:

package com.example;

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

public class Example {
    private static final Logger LOGGER = LogManager.getLogger();

    public static void main(String... args) {
        String thing = args.length > 0 ? args[0] : "world";
        LOGGER.info("Hello, {}!", thing);
        LOGGER.debug("Got calculated value only if debug enabled: {}", () -> doSomeCalculation());
    }

    private static Object doSomeCalculation() {
        // do some complicated calculation
    }
}

And an example log4j2.xml configuration file:

<?xml version="1.0" encoding="UTF-8"?>
<Configuration>
  <Appenders>
    <Console name="Console" target="SYSTEM_OUT">
      <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
    </Console>
  </Appenders>
  <Loggers>
    <Logger name="com.example" level="INFO"/>
    <Root level="error">
      <AppenderRef ref="Console"/>
    </Root>
  </Loggers>
</Configuration>

Documentation

The Log4j 2 User's Guide is available here or as a downloadable PDF.

Requirements

• Java 8 users should use 2.17.1 or greater.
• Java 7 users should use 2.12.4.
• Java 6 users should use 2.3.2.
• Some features require optional dependencies; the documentation for these features specifies the dependencies.

License

Apache Log4j 2 is distributed under the Apache License, version 2.0.

Download

How to download Log4j, and how to use it from Maven, Ivy and Gradle. You can access the latest development snapshot by using the Maven repository https://repository.apache.org/snapshots, see Snapshot builds.

Issue Tracking

Issues, bugs, and feature requests should be submitted to the JIRA issue tracking system for this project.

Pull request on GitHub are welcome, but please open a ticket in the JIRA issue tracker first, and mention the JIRA issue in the Pull Request.

Building From Source

See [the detailed build instructions](BUILDING.md) on how to build to the project and website from sources.

Contributing

We love contributions! Take a look at [our contributing page](CONTRIBUTING.md).