public static Logger exists(String name) 
{
    return getLoggerRepository().exists(name);
}

 public static Enumeration getCurrentLoggers() 
{
    return getLoggerRepository().getCurrentLoggers();
}

 public static Logger getLogger(String name) 
{
     // Delegate the actual manufacturing of the logger to the logger repository.
    return getLoggerRepository().getLogger(name);
}

Retrieve the appropriate Logger instance.

 public static Logger getLogger(Class clazz) 
{
     // Delegate the actual manufacturing of the logger to the logger repository.
    return getLoggerRepository().getLogger(clazz.getName());
}

Retrieve the appropriate Logger instance.

 public static Logger getLogger(String name,
    LoggerFactory factory) 
{
     // Delegate the actual manufacturing of the logger to the logger repository.
    return getLoggerRepository().getLogger(name, factory);
}

Retrieve the appropriate Logger instance.

 public static LoggerRepository getLoggerRepository() 
{
    if (repositorySelector == null) {
        repositorySelector = new DefaultRepositorySelector(new NOPLoggerRepository());
        guard = null;
        LogLog.error("LogMananger.repositorySelector was null likely due to error in class reloading, using NOPLoggerRepository.");
    }
    return repositorySelector.getLoggerRepository();
}

 public static Logger getRootLogger() 
{
     // Delegate the actual manufacturing of the logger to the logger repository.
    return getLoggerRepository().getRootLogger();
}

Retrieve the appropriate root logger.

 public static  void resetConfiguration() 
{
    getLoggerRepository().resetConfiguration();
}

 public static  void setRepositorySelector(RepositorySelector selector,
    Object guard) throws IllegalArgumentException 
{
   
    // By default we use a DefaultRepositorySelector which always returns 'h'.
    Hierarchy h = new Hierarchy(new RootLogger((Level) Level.DEBUG));
    repositorySelector = new DefaultRepositorySelector(h);
    /** Search for the properties file log4j.properties in the CLASSPATH.  */
    String override =OptionConverter.getSystemProperty(DEFAULT_INIT_OVERRIDE_KEY,
						       null);
    // if there is no default init override, then get the resource
    // specified by the user or the default config file.
    if(override == null || "false".equalsIgnoreCase(override)) {
      String configurationOptionStr = OptionConverter.getSystemProperty(
							  DEFAULT_CONFIGURATION_KEY, 
							  null);
      String configuratorClassName = OptionConverter.getSystemProperty(
                                                   CONFIGURATOR_CLASS_KEY, 
						   null);
      URL url = null;
      // if the user has not specified the log4j.configuration
      // property, we search first for the file "log4j.xml" and then
      // "log4j.properties"
      if(configurationOptionStr == null) {	
	url = Loader.getResource(DEFAULT_XML_CONFIGURATION_FILE);
	if(url == null) {
	  url = Loader.getResource(DEFAULT_CONFIGURATION_FILE);
	}
      } else {
	try {
	  url = new URL(configurationOptionStr);
	} catch (MalformedURLException ex) {
	  // so, resource is not a URL:
	  // attempt to get the resource from the class path
	  url = Loader.getResource(configurationOptionStr); 
	}	
      }
      // If we have a non-null url, then delegate the rest of the
      // configuration to the OptionConverter.selectAndConfigure
      // method.
      if(url != null) {
	    LogLog.debug("Using URL ["+url+"] for automatic log4j configuration.");
        try {
            OptionConverter.selectAndConfigure(url, configuratorClassName,
					   LogManager.getLoggerRepository());
        } catch (NoClassDefFoundError e) {
            LogLog.warn("Error during default initialization", e);
        }
      } else {
	    LogLog.debug("Could not find resource: ["+configurationOptionStr+"].");
      }
    }  
    if((LogManager.guard != null) && (LogManager.guard != guard)) {
      throw new IllegalArgumentException(
           "Attempted to reset the LoggerFactory without possessing the guard.");
    }
    if(selector == null) {
      throw new IllegalArgumentException("RepositorySelector must be non-null.");
    }
    LogManager.guard = guard;
    LogManager.repositorySelector = selector;
}

Sets LoggerFactory but only if the correct guard is passed as parameter.

Initally the guard is null. If the guard is null, then invoking this method sets the logger factory and the guard. Following invocations will throw a IllegalArgumentException , unless the previously set guard is passed as the second parameter.

This allows a high-level component to set the RepositorySelector used by the LogManager.

For example, when tomcat starts it will be able to install its own repository selector. However, if and when Tomcat is embedded within JBoss, then JBoss will install its own repository selector and Tomcat will use the repository selector set by its container, JBoss.

 public static  void shutdown() 
{
    getLoggerRepository().shutdown();
}