Log4j in Spring mvc controllers: how to remove duplication

Question

In each controller I have in my Spring MVC webapp, there's this line:

static Logger logger = Logger.getLogger(ControllerName.class);

It's a little duplication. How can I write "logger-provided" controllers, without repeating this line every time?

Thanks

Answer 1

Maybe you don't like it, but one of the things I love about Project Lombok is this one. You can annotate your class with @Log4j (or better, @Slf4j) in order to get an invisible Logger called log.

Answer 2

First suggestion is to have a common base class for all controllers with the following line:

public abstract class AbstractBaseController {

    protected Logger logger = Logger.getLogger(this.getClass());

}

Note that the logger is not longer static - this isn't really an issue with singleton Spring services/controllers, but still I find it a bit awkward. See also: Why do we declare Loggers static final?

Also it is a bit against OO principles and does not allow you to inherit from anything else. This is actually a limitation of a Java language, in Scala/slf4s you can write:

class SomeController extends BaseController with Logging 

Where BaseController is a base class and Logging is a trait that mixes-in logger field to a SomeController class. Very convenient.