如何指定 Log4J 2.x 配置位置？

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

在 Windows 中，请注意您需要使用带有log4j.configurationFile属性的 URI

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

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

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 5

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 6

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 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");
    }
}

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;
    }