Log into different files with the same logger with Log4j

Question

I have a Class "Example.class". I get my Logger with:

    private final Logger log = Logger.getLogger(Example.class);

My log4j.properties looks like:

    log4j.appender.file=org.apache.log4j.RollingFileAppender
    log4j.appender.file.File=log.txt

    log4j.appender.file.MaxFileSize=1024KB
    log4j.appender.file.MaxBackupIndex=5

    log4j.appender.file.layout=org.apache.log4j.PatternLayout
    log4j.appender.file.layout.ConversionPattern=%p %t %c - %m%n

My Class is logging via log.info(..), log.debug(..) and so on into the file . 。

Now i want to have a different logger for the same class eg:

    private final Logger differentLogger = Logger.getLogger(Example.class);

and this logger should log into a different file for example

    differentLogger.info("Hello World");
    //writes 'Hello World' into differentLogFile.txt

Is this possible somehow?

Answer 1

No, the category identifies the logger.

That said, you are not forced to use the class as the category. You could use in the same class:

private final Logger log = Logger.getLogger(Example.class);

private final Logger differentLogger = Logger.getLogger(mylogs.different);

After that, in the configuration file you can define several appenders and assign each category to a different appender.

Answer 2

Calling Logger.getLogger(Example.class) twice will return the same or undistinguishable instances of Logger . This means Log4J cannot make any distinction between them and they will always land up in the same file.

The solution is obvious: use a different logger!

Logger differentLogger = Logger.getLogger("differentLogger");

And configure log4j.xml to use different appender for differentLogger .