Log4J Log Formatting
Apache log4j supports various Layout objects, each of which can format logging data according to various layouts. We can also create a Layout object that formats logging data in an application-specific way.
All Layout objects receive a LoggingEvent object from the Appender objects. The Layout objects then retrieve the message argument from the LoggingEvent and apply the appropriate ObjectRenderer to get the String representation of the message.
There is one top-level abstract class in log4j is org.apache.log4j.Layout. It is the base class for all other layout classes in the log4j API.
The Layout class is defined as an abstract class within an application; we don?t need to use this class directly; instead, we work on subclasses which are as follows:
This class provides a skeleton implementation of all common operations across all other objects and declares two abstract methods:
Apart from these abstract methods, the Layout class provides concrete implementation for the methods given below:
Each subclass can return information related to class by overriding the concrete implementation of these methods.