plugins

[Nicholas Duane]

I've got a couple questions regarding plugins I'm hoping someone might be able 
to help me with.  I checked the docs and it's still not quite clear.
 
1. I'm unsure what to set printObject to in my Plugin annotation.  From 
http://logging.apache.org/log4j/2.x/manual/extending.html it says:
 
"Specifying the printObject attribute with a value of "true" indicates that a 
call to toString will format the arguments to the filter as the configuration 
is being processed."
 
which unfortunately doesn't clear things up any.  I looked at the docs for 
printObject and that doesn't say anything other than it's a Boolean and its 
default is false.
 
2. I created a LevelRangeFiler and I'm trying to figure out how to get it 
loaded by log4j.  I read over the instructions on plugins located at 
http://logging.apache.org/log4j/2.x/manual/plugins.html but since I'm a java 
noob I'm still a bit lost.  I'm wondering, if I just have a .java class which I 
compile to a .class file, can that be used?  If so, how?
 
Below is the filter I wrote based on looking at the threshold filter example at 
http://logging.apache.org/log4j/2.x/manual/extending.html.

import org.apache.logging.log4j.core.filter.AbstractFilter;
import org.apache.logging.log4j.core.Filter;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
import org.apache.logging.log4j.core.config.plugins.PluginFactory;
import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.Logger;
import org.apache.logging.log4j.Marker;
import org.apache.logging.log4j.message.Message;

@Plugin(name="LevelRangeFilter", category="Core", elementType="filter",
        printObject=true)
public class LevelRangeFilter extends AbstractFilter
{
    private final Level minLevel;
    private final Level maxLevel;
    
    public LevelRangeFilter(Level minLevel, Level maxLevel,
            Filter.Result onMatch, Filter.Result onMismatch)
    {
    super(onMatch, onMismatch);
    this.minLevel = minLevel;
    this.maxLevel = maxLevel;
    }

    private Result filter(Level level)
    {
    if (level.isMoreSpecificThan(this.minLevel) &&
            level.isLessSpecificThan(this.maxLevel))
        {
        return this.onMatch;
        }
    return this.onMismatch;
    }

    public Filter.Result filter(Logger logger, Level level,
            Marker marker, String msg, Object[] params)
    {
    return filter(level);
    }

    public Filter.Result filter(Logger logger, Level level,
        Marker marker, Object msg, Throwable t)
    {
    return filter(level);
    }

    public Filter.Result filter(Logger logger, Level level,
        Marker marker, Message msg, Throwable t)
    {
    return filter(level);
    }

    public Filter.Result filter(LogEvent event)
    {
    return filter(event.getLevel());
    }
    
    @PluginFactory
    public static LevelRangeFilter createFilter(
        @PluginAttribute(value="minLevel",
        defaultString="DEBUG") Level minLevel,
        @PluginAttribute(value="maxLevel",
        defaultString="FATAL") Level maxLevel,
        @PluginAttribute(value="onMatch",
        defaultString="NEUTRAL") Result onMatch,
        @PluginAttribute(value="onMismatch",
        defaultString="DENY") Result onMismatch)
    {
    return new LevelRangeFilter(minLevel, maxLevel, onMatch, onMismatch);
    }
}

Thanks,
Nick