Comments on: Log4j MDC (Mapped Diagnostic Context) : Example code

By: john jimenez

john jimenez — Wed, 10 Feb 2010 00:26:37 +0000

an output of the log file might add value to already a great post.

also, the username may be accessed from the request (i.e., request.getPrincipal().getName())

By: eiweißpulver

eiweißpulver — Wed, 02 Dec 2009 01:22:54 +0000

The NDC and MDC log4j classes are used to store program/application contextual information that can then be used when logging messages. The NDC class name is org.apache.log4j.NDC. “NDC” stands for “Nested Diagnostic Context”. The MDC class name is org.apache.log4j.MDC. “MDC” stands for “Mapped Diagnostic Context”. NDC has been part of the log4j framework longer than MDC. If you haven't already, you may want to review the javadoc information for each class.

By: Veera

Veera — Fri, 27 Nov 2009 22:18:20 +0000

exactly.

By: diät pillen

diät pillen — Fri, 27 Nov 2009 21:36:52 +0000

The “Mapped Diagnostic Context” implements a “map” into which key/value pair information can be stored. Just like NDC, the context is stored per thread. Values are stored by key name. Each thread could use the same key name but have different stored values. Values are stored/retreived/removed by using the familiar pattern of MDC.put(), MDC.get(), and MDC.remove() methods.