How to specify Log4J 2.x config location?

Question

Is there any way to specify Log4J 2.x log4j2.xml file location manually (like DOMConfigurator in Log4J 1.x), without messing with classpath and system properties?

Answer 1

You could use the static method #initialize(String contextName, ClassLoader loader, String configLocation) (see source here) in org.apache.logging.log4j.core.config.Configurator. (You can pass null for the class loader.)

Be aware that this class is not part of the public API so your code may break with any minor release.

For completeness, you can also specify the location of the configuration file with this system property:

-Dlog4j.configurationFile=path/to/log4j2.xml

Answer 2

For log4j version 2.12.1, you can find how to reconfigure log4j2 here.

Below is an example

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

File file = new File("C:\\Path for Windows OS\\yourConfig.xml");
    
LoggerContext context = (LoggerContext) LogManager.getContext(false);
context.setConfigLocation(file.toURI());
    
Logger log  = LogManager.getLogger(YourClass.class);

It seems to me that way of configuring log4j2 is changing with new releases, so you should be aware of that.

Answer 3

If you are using log4j2 and properties are in defined in log4j2.properties file then use this.

-Dlog4j2.configurationFile=file:/home/atul/log4j2.properties

Answer 4

In Windows, be aware that you need to use a URI with the log4j.configurationFile property

-Dlog4j.configurationFile=file://C:\path\to\log4j2.xml

Answer 5

Using the LoggerContext allows to setConfigLocation.

File f = new File(this.logConfigFile);
URI fc = f.toURI();         
System.out.println("Loading logging config file: " + fc);
Logger l = (Logger) LogManager.getLogger(LogManager.ROOT_LOGGER_NAME);
l.getContext().setConfigLocation(fc);

or alternatively

LoggerContext.getContext().setConfigLocation(java.net.URI);

Answer 6

You can initialize like below as well

ConfigurationSource source = new ConfigurationSource(new FileInputStream(log4j file Path));
XmlConfiguration xmlConfig = new XmlConfiguration(source);
Logger logger = (Logger) LogManager.getLogger(); 
logger.getContext().start(xmlConfig); 

In each class you can get logger instance as below

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

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

Answer 7

Step: 1 - Get ready with your log4J.xml file with the appender details (Mostly under the resource folder)

Step: 2 - Following code should be added to the configuration class (In the previous log4J we had PropertyConfigurator and now we need to go with LoggerContext)

String log4JFilePath = "file path of your log4J.xml file";
LoggerContext loggerContext = (LoggerContext)LoggerManager.getContext(false);
File file = new File(log4JFilePath);
loggerContext.setConfigLocation(file.toURI());

Step: 3 - Add the following line to utilise the logger in any classes

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

logger.info("log here");

 

Answer 8

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

public class Foo {
    public static void main(String[] args) {

     Configurator.initialize(null, "src/main/config/log4j2.xml"); //path specify

     Logger logger = LogManager.getLogger(APITestToolMain.class);
     logger.info("working");
    }
}

resource: https://www.baeldung.com/spring-boot-change-log4j2-location

Answer 9

void initializeLogger()
{      
    try
        {
            String basepath=checkpath();
            File f = new File(basepath+"\\config\\log4j2.properties");
            URI fc = f.toURI(); 
            LoggerContext context = (LoggerContext) LogManager.getContext(false);
            context.setConfigLocation(f.toURI());
        }
        catch (Exception e)
        {
            errorlog="Unable to load logging property:";
            System.out.println(errorlog+": "+e.getMessage());
        }   
}

This is the way I initialize my log4j2 properties file from a different location, so what I simply do is to call the initializeLogger() method in my main method.

And it works perfectly.

Perhaps you need to see what the checkpath() blocks looks like, I added the function below.

String checkpath()
    {
        String parentpath="";
        try
        {
           URL url=getClass().getProtectionDomain().getCodeSource().getLocation();
           File f=new File(url.toURI());
           parentpath=f.getParent();
        }
        catch(Exception ex)
        {
            //logger.error("unable to retrieve application parent path");
        }
        return parentpath;
    }