Issue with log4j log not writing to file

问题

Does anyone see why this log is not writing to file. It is writing to standard out twice but not to the file:

Also, I tried removing the "Stdout" appender and then I don't get any logging at all.

package org.berlin.wicket;
import org.apache.log4j.Logger;
private static final Logger LOG = Logger.getLogger(QuickstartPage.class);
LOG.info("Loading constructor");

log4j.rootLogger=DEBUG,Stdout,mainAppender

log4j.appender.Stdout=org.apache.log4j.ConsoleAppender log4j.appender.Stdout.layout=org.apache.log4j.PatternLayout

log4j.appender.Stdout.layout.conversionPattern=%-5p - %-26.26c{1} - %m\n

log4j.appender.mainAppender=org.apache.log4j.DailyRollingFileAppender

log4j.appender.mainAppender.file=logs/core.log

log4j.appender.mainAppender.datePattern='.'yyyy-MM-dd

log4j.appender.mainAppender.append=true

log4j.appender.mainAppender.layout=org.apache.log4j.PatternLayout

log4j.appender.mainAppender.layout.ConversionPattern=[%d{MM/dd/yyyy HH:mm:ss.SSS}] [%C{1}.%M():%L] [%t] [%p] - %m%n

log4j.logger.org.berlin=DEBUG,Stdout,mainAppender

回答1:

You have two loggers which use the same appender (Stdout), hence why you see entries on the console twice.

As others have mentioned, the properties are case-sensitive, hence why your file appender is not configured correctly.

回答2:

The File and Append properties are case senstive.

log4j.appender.mainAppender.File=someFileName.log log4j.appender.mainAppender.Append=true

回答3:

You should create an instance of FileHandler that writes log to a file called myfile.log.

FileHandler fileHandler = new FileHandler("myfile.log", true);        
logger.addHandler(fileHandler);

来源：https://stackoverflow.com/questions/13954394/issue-with-log4j-log-not-writing-to-file