How to change Appender layout programmatically in log4j2?

Question

Previously in log4j 1.x I was able to to appender.setLayout() on and Appender but now in log4j 2.x there is no such method as setLayout(). How can I set a layout to an Appender object programmatically in log4j2 ?

Conjoined

Have you tried using the documentation? I couldn't find a duplicate of your question on SO though. – Arber

@TimBiegeleisen I did try the documentattion. I couldn't yet find a setLayout() method. – Conjoined

The real question is what are you really trying to do? Why is it necessary to change the Layout programmatically? There may be a better way to do what you really want. – Hotshot

I am trying to change log4j2 configuration at runtime allowing the configuration to be changed through JMX beans. This was possible with log4j 1.x (but i believe 1.x is synchronous hence slower) therefore trying to upgrade to 2.x and do the same. I just found in the log4j website that log4j2 does not have a lot of support for changing configurations programatically. – Conjoined

Answer 1

There is no setLayout() method. You will need to get the current Configuration and update it during runtime as explained in the documentation.

Westering

Thank you. What if the only thing I want is just to change layout of appender. Can you provide me an example please. – Conjoined

Answer 2

If, by chance, you simply want to change the pattern used for different kinds of log events you can use the pattern selector. Otherwise, understanding your use case better might provide other alternatives. In fact, I would love to know why you would want to change the layout programmatically as it is unusual to have a request to do that.

Hotshot

Can you show how to use pattern selector programmaticallyy? – Canikin

Answer 3

You can add you own layout in this way (example with ConsoleAppender):

// rootLoggerConfig you can get from LoggerContext.getRootLogger().get()

String pattern = "%d [%p|%c|%C{1}] %m%n"; // your pattern here

PatternLayout pl = PatternLayout.newBuilder().withPattern(pattern).build();
ConsoleAppender consoleAppender = ConsoleAppender.createDefaultAppenderForLayout(pl);

rootLoggerConfig.addAppender(consoleAppender, Level.getLevel("INFO"), filter);

// filter - your implementation of 
// org.apache.logging.log4j.core.filter.AbstractFilter

Polydipsia