[Log4j] Define

Define

log4j is a reliable, fast and flexible logging framework written in Java, which is distributed under the Apache Software License

log4j has been ported to the C, C++, C# Perl, Python, Ruby...

1. Main components

- loggers : Responsible for capturing logging information

- appenders : Responsible for publishing logging information to various preferred destinations

- layouts : Responsible for formatting logging information in different styles