How to load log4j2 xml file programmatically ?

In this post, We will learn How to load log4j2 xml file programmatically using a demo project?

In this example, We have kept our log4j2.xml in the config folder inside the project(instead of keeping log4j2.xml inside src\main\resources).

pom.xml

We have added log4j2 log4j-api & log4j-core dependency in the dependencies section.

<project xmlns="http://maven.apache.org/POM/4.0.0"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.kkjavatutorials.org</groupId>
	<artifactId>LoadLog4j2xmlFileProgrammaticallyExample</artifactId>
	<version>0.0.1-SNAPSHOT</version>

	<properties>
		<maven.compiler.source>1.8</maven.compiler.source>
		<maven.compiler.target>1.8</maven.compiler.target>
	</properties>

	<dependencies>
		<dependency>
			<groupId>org.apache.logging.log4j</groupId>
			<artifactId>log4j-api</artifactId>
			<version>2.17.1</version>
		</dependency>
		<dependency>
			<groupId>org.apache.logging.log4j</groupId>
			<artifactId>log4j-core</artifactId>
			<version>2.17.1</version>
		</dependency>
	</dependencies>

</project>

<project xmlns="http://maven.apache.org/POM/4.0.0"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

<groupId>com.kkjavatutorials.org</groupId>

<artifactId>LoadLog4j2xmlFileProgrammaticallyExample</artifactId>

<version>0.0.1-SNAPSHOT</version>

<maven.compiler.source>1.8</maven.compiler.source>

<maven.compiler.target>1.8</maven.compiler.target>

</properties>

<groupId>org.apache.logging.log4j</groupId>

</dependency>

<groupId>org.apache.logging.log4j</groupId>

</dependency>

</dependencies>

</project>

log4j2.xml

I have created log4j2.xml configuration file in the config folder inside the project

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="warn">

    <Appenders>
    	<!-- configuration of Console appender -->
        <Console name="console" target="SYSTEM_OUT">
          <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n" />
        </Console>
    </Appenders>
    
    <Loggers>
    	<!-- Here Root logger is referring to console appender -->
        <Root level="debug" additivity="false">
            <AppenderRef ref="console" />
        </Root>
    </Loggers>
    
</Configuration>

<?xml version="1.0" encoding="UTF-8"?>

</Console>

</Appenders>

</Root>

</Loggers>

</Configuration>

MyUtil.java

package com.kkjavatutorials.util;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;

import org.apache.logging.log4j.core.config.ConfigurationSource;
import org.apache.logging.log4j.core.config.Configurator;

public class MyUtil {

	//Utility method to support load log4j2.xml file
	public static void loadLog4j2Config(String logConfigurationFile) {
		try {
			InputStream inputStream = new FileInputStream(logConfigurationFile);
			ConfigurationSource source = new ConfigurationSource(inputStream);
			Configurator.initialize(null, source);
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}

package com.kkjavatutorials.util;

import java.io.FileInputStream;

import java.io.IOException;

import java.io.InputStream;

import org.apache.logging.log4j.core.config.ConfigurationSource;

import org.apache.logging.log4j.core.config.Configurator;

public class MyUtil {

//Utility method to support load log4j2.xml file

public static void loadLog4j2Config(String logConfigurationFile) {

try {

InputStream inputStream = new FileInputStream(logConfigurationFile);

ConfigurationSource source = new ConfigurationSource(inputStream);

Configurator.initialize(null, source);

} catch (IOException e) {

e.printStackTrace();

}

ClientTest.java

Now we are going to test our logger. For this, I’ve written below test class.

package com.kkjavatutorials.client;

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

import com.kkjavatutorials.util.MyUtil;

public class ClientTest {
	//This static block has to be executed very first
	static {
		MyUtil.loadLog4j2Config("config/log4j2.xml");
	}
	
	private static final Logger logger = LogManager.getLogger(ClientTest.class);

	public static void main(String[] args)  {
		logger.info("Logging info message");
		logger.warn("Logging warn message");
		logger.error("Logging error message");
	}
}

package com.kkjavatutorials.client;

import org.apache.logging.log4j.LogManager;

import org.apache.logging.log4j.Logger;

import com.kkjavatutorials.util.MyUtil;

public class ClientTest {

//This static block has to be executed very first

static {

MyUtil.loadLog4j2Config("config/log4j2.xml");

}

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

public static void main(String[] args) {

logger.info("Logging info message");

logger.warn("Logging warn message");

logger.error("Logging error message");

}

If you run ClientTest.java as a java application then you’ll find the below output:

16:18:18.290 [main] INFO com.kkjavatutorials.client.ClientTest – Logging info message
16:18:18.290 [main] WARN com.kkjavatutorials.client.ClientTest – Logging warn message
16:18:18.290 [main] ERROR com.kkjavatutorials.client.ClientTest – Logging error message

That’s All about How to load log4j2 xml file programmatically?

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