Log4j Concepts: Difference between revisions

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=Logger=
=Logger=


Logger is a subclass of [[#Category|Category]] and extends it. [[#Category|Category]] has been deprecated.
Logger is a subclass of [[#Category|Category]] and extends it. [[#Category|Category]] has been deprecated. Internally, whenever log4j is asked to produce a Category object, it will instead produce a Logger object. In order to preserve backward compatibility, methods that previously accepted category objects still continue to accept category objects.
 


=Category=
=Category=


<blockquote style="background-color: Gold; border: solid thin Goldenrod;">
<blockquote style="background-color: Gold; border: solid thin Goldenrod;">
:This class has been deprecated and replaced with the [[#Logger|Logger]] subclass.<br>
:This class has been deprecated and replaced with the [[#Logger|Logger]] subclass. There is no need for new client code to use or refer to the Category class.
</blockquote>
</blockquote>
  * <p><code>Logger</code> is a subclass of Category, i.e. it extends
  * Category. In other words, a logger <em>is</em> a category. Thus,
  * all operations that can be performed on a category can be
  * performed on a logger. Internally, whenever log4j is asked to
  * produce a Category object, it will instead produce a Logger
  * object. Log4j 1.2 will <em>never</em> produce Category objects but
  * only <code>Logger</code> instances. In order to preserve backward
  * compatibility, methods that previously accepted category objects
  * still continue to accept category objects.
  *
  * <p>For example, the following are all legal and will work as
  * expected.
  *
  <pre>
    &nbsp;&nbsp;&nbsp;// Deprecated form:
    &nbsp;&nbsp;&nbsp;Category cat = Category.getInstance("foo.bar")
 
    &nbsp;&nbsp;&nbsp;// Preferred form for retrieving loggers:
    &nbsp;&nbsp;&nbsp;Logger logger = Logger.getLogger("foo.bar")
  </pre>
 
  *  <p>The first form is deprecated and should be avoided.
  *
  *  <p><b>There is absolutely no need for new client code to use or
  *  refer to the <code>Category</code> class.</b> Whenever possible,
  *  please avoid referring to it or using it.
  *
  * <p>See the <a href="../../../../manual.html">short manual</a> for an
  * introduction on this class.
  * <p>
  * See the document entitled <a href="http://www.qos.ch/logging/preparingFor13.html">preparing
  *  for log4j 1.3</a> for a more detailed discussion.
  *

Revision as of 23:55, 7 August 2016

Internal

Logger

Logger is a subclass of Category and extends it. Category has been deprecated. Internally, whenever log4j is asked to produce a Category object, it will instead produce a Logger object. In order to preserve backward compatibility, methods that previously accepted category objects still continue to accept category objects.


Category

This class has been deprecated and replaced with the Logger subclass. There is no need for new client code to use or refer to the Category class.
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