[jboss-user] [Beginners Corner] - Re: Web Application Context Logging (log4j) Question

[sstacha]

Yes,  I include log4j-1.2.8 in each webapp's WEB-INF/lib folder.  Let me go ahead and post the background code and such then.

First, I was trying to load a context event listener with the following code:

package biz.ormia.util.logging;

/**
 * User: sstacha
 * Date: May 3, 2009
 * Time: 1:22:11 PM
 * Attempt to do logging without much effort on the devleopers part.
 * Developers will need to add the following the web.xml file
 * 
 * 	<listener-class>biz.ormia.util.logging.ContextRepositoryListener</listener-class>
 * 
 *
 */

import org.apache.log4j.spi.WebAppRepositorySelector;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import java.util.Enumeration;

public class ContextRepositoryListener implements ServletContextListener
{
    public void contextInitialized(ServletContextEvent contextEvent)
    {
        try
		{
			System.out.println("Attempting to add a context to the repositorySelector: " + contextEvent.getServletContext().getServletContextName());
			Enumeration names=contextEvent.getServletContext().getAttributeNames();
			System.out.println("----- attributes -----");
			String name;
			while (names.hasMoreElements())
			{
				name = (String)names.nextElement();
				System.out.println("     " + name + " - " + contextEvent.getServletContext().getAttribute(name));
			}
			names=contextEvent.getServletContext().getInitParameterNames();
			System.out.println("----- init params -----");
			while (names.hasMoreElements())
				System.out.println("     " + names.nextElement());
			WebAppRepositorySelector.init(contextEvent.getServletContext());
			
			//ContextRepositorySelector.init(contextEvent.getServletContext());

        }
        catch (Exception ex) {System.err.println(ex);}
    }

	public void contextDestroyed(ServletContextEvent contextEvent)
	{
		System.out.println("Attempting to remove a context from the repositorySelector: " + contextEvent.getServletContext());
        ContextRepositorySelector.removeContext();
	}
}


As you can see mostly I was trying to figure out what I had available to me and make sure it was being called.  The only real thing in init is to call the 
WebAppRepositorySelector.init(contextEvent.getServletContext());
WebAppRepositorySelector is my implementation which simply tries to take the default respository that jboss sets up and then tries to add a new one for each webapp deployment.

package org.apache.log4j.spi;

import org.apache.log4j.LogManager;
import org.apache.log4j.Hierarchy;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import java.util.Map;
import java.util.HashMap;

/**
 * User: sstacha
 * Date: May 5, 2009
 * Time: 2:58:16 PM
 * To change this template use File | Settings | File Templates.
 */
public class WebAppRepositorySelector implements RepositorySelector
{
	private static Map<ClassLoader, LoggerRepository> repositories = new HashMap<ClassLoader, LoggerRepository>();
	private static LoggerRepository defaultRepository;

	public static void init(ServletContext context) throws ServletException
	{
		System.out.println("in addContext...");
		System.out.println("current thread: " + Thread.currentThread().getName());
		System.out.println("classloader: " + Thread.currentThread().getContextClassLoader().toString());
		System.out.println("context: " + context.getServletContextName());
		if (defaultRepository == null)
		{
			defaultRepository = LogManager.getLoggerRepository();
			Object guard = LogManager.getRootLogger();
			LogManager.setRepositorySelector(new WebAppRepositorySelector(), guard);
		}
		System.out.println("defaultRepository: " + defaultRepository.toString());

		org.apache.log4j.Logger rootLogger = new RootLogger(org.apache.log4j.Level.DEBUG);
		System.out.println("rootLogger: " + rootLogger);
//		org.apache.log4j.Hierarchy hierarchy = new Hierarchy(rootLogger);
//
//		try {repositories.put(Thread.currentThread().getContextClassLoader(), hierarchy);}
//		catch (Exception ex) {System.out.println("Exception while creating new heiarchy for repository: " + ex);}
//		if (defaultRepository == null)
//		{
//			defaultRepository = LogManager.getLoggerRepository();
//			Object guard = LogManager.getRootLogger();
//			LogManager.setRepositorySelector(new CTXRepositorySelector(), guard);
//		}
//		// add our thread instance in for lookup later
//		Hierarchy hierarchy = new Hierarchy(new RootLogger(Level.DEBUG));
//		try {repositories.put(Thread.currentThread().getContextClassLoader(), hierarchy);}
//		catch (Exception ex) {System.out.println("Exception while creating new heiarchy for repository: " + ex);}
	}

	public static synchronized void removeContext()
	{
		System.out.println("in removeContext...");
		System.out.println("current thread: " + Thread.currentThread().getName());
		System.out.println("classloader: " + Thread.currentThread().getContextClassLoader().toString());
	}


	private WebAppRepositorySelector() { }

	public LoggerRepository getLoggerRepository()
	{
		System.out.println("in getLoggerRepository...");
		System.out.println("current thread: " + Thread.currentThread().getName());
		System.out.println("classloader: " + Thread.currentThread().getContextClassLoader().toString());
		ClassLoader cl = Thread.currentThread().getContextClassLoader();
//		Hierarchy hierarchy = (Hierarchy) repositories.get(cl);
//
//		if (hierarchy == null) {
//		  hierarchy = new Hierarchy(new RootLogger(org.apache.log4j.Level.DEBUG));
//		  hierMap.put(cl, hierarchy);
//		}
//
//		return hierarchy;
		LoggerRepository repository = null;
		try
		{
			repository = repositories.get(Thread.currentThread().getContextClassLoader());
		}
		catch (Exception ex) {System.out.println("Exception in getLoggerRepository getting the repository from the class loader: " + ex);}
		if (repository == null)
		{
			System.out.println("respository is null using default...");
			return defaultRepository;
		}
		else
		{
			System.out.println("Using repository: " + repository);
			return repository;
		}
//		if (repository == null)
//			return defaultRepository;
//		return repository;
//		if (defaultRepository != null)
//			return defaultRepository;
//		return null;
	}
}


Note that this works as I have it commented here but I am not doing anything aside from saving off the original jboss repository and then resetting the selector to ourselves.  If I uncomment the next line:

org.apache.log4j.Hierarchy hierarchy = new Hierarchy(rootLogger);

Then I get the error mentioned above.  If I don't put my Selector in the log4j...spi package then I get a generic error:

[ERROR] - Exception sending context initialized event to listener instance of class biz.ormia.util.logging.ContextRepositoryListener
java.lang.VerifyError: (class: biz/ormia/util/logging/ContextRepositorySelector, method: init signature: (Ljavax/servlet/ServletContext;)V) Incompatible argument to function


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