Utility to merge Log4j2Plugins.dat files

README.md

This program is based on my reading of the Log4J source code from tag rel/2.21.0. It produces the same output for my Log4J2 example as the official transformer plugin, but I make no guarantees as to whether it will do so for any other version of Log4J.

CombinePluginFiles.java

import java.io.FileOutputStream;
import java.net.URL;
import java.util.Enumeration;

import org.apache.logging.log4j.core.config.plugins.processor.PluginCache;


/**
 *  A utility to combine the Log4j2Plugins.dat files from multiple JARs on the
 *  classpath, writing the output to the current working directory.
 */
public class CombinePluginFiles
{

    public static void main(String[] args)
    throws Exception
    {
        System.out.println("running");
        Enumeration<URL> datFiles = Thread.currentThread().getContextClassLoader().getResources("META-INF/org/apache/logging/log4j/core/config/plugins/Log4j2Plugins.dat");
        PluginCache cache = new PluginCache();
        cache.loadCacheFiles(datFiles);
        try (FileOutputStream out = new FileOutputStream("Log4j2Plugins.dat"))
        {
            cache.writeCache(out);
        }
    }
}