Log4j separate logging

log4j.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration PUBLIC "-//LOGGER"
        "http://logging.apache.org/log4j/1.2/apidocs/org/apache/log4j/xml/doc-files/log4j.dtd">
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">

    <appender name="console" class="org.apache.log4j.ConsoleAppender">
        <param name="Target" value="System.out"/>
        <layout class="org.apache.log4j.PatternLayout">
            <param name="ConversionPattern" value="%-5p - %m%n"/>
        </layout>
    </appender>

    <logger name="filtered">
        <level value="debug" />
    </logger>

    <root>
        <priority value="debug"/>
        <appender-ref ref="console"/>
    </root>
    
</log4j:configuration>

Log4jFilteredLogging.java

import org.apache.log4j.Appender;
import org.apache.log4j.FileAppender;
import org.apache.log4j.Logger;
import org.apache.log4j.MDC;
import org.apache.log4j.PatternLayout;
import org.apache.log4j.spi.Filter;
import org.apache.log4j.spi.LoggingEvent;

import java.io.IOException;

public class Log4jFilteredLogging {

    private static final String CONTEXT_KEY = "filteringContextKey";

    private static final Logger log = Logger.getLogger("filtered");

    public static void main(String[] args) throws Exception {

        doJob("filtering1");
        doJob("filtering2");
    }

    private static void doJob(String jobName) throws IOException {
        prepareLog(jobName);
        log.info(jobName + " - doJob");
    }

    private static void prepareLog(String name) throws IOException {
        if (log.getAppender(name) == null) {
            Appender app = new FileAppender(new PatternLayout(), "/tmp/" + name + ".log");
            app.setName(name);
            Filter filter = new MDCFilter(CONTEXT_KEY, name);
            app.addFilter(filter);
            log.addAppender(app);
        }
        MDC.put(CONTEXT_KEY, name);
    }

    private static class MDCFilter extends Filter {

        private String key;
        private String value;

        private MDCFilter(String key, String value) {
            this.key = key;
            this.value = value;
        }

        @Override
        public int decide(LoggingEvent event) {
            Object value = MDC.get(key);
            if (value != null && value.equals(this.value))
                return Filter.ACCEPT;
            return Filter.DENY;
        }
    }
}