If you're only using one log4j2 config for the whole server, then it
doesn't really matter which LoggerContext you're using as there should only
be one (LoggerContext usually maps directly to a config file or similar
config source). And yes, log4j-web is only useful in the context where you
bundle log4j-api and log4j-core in your WEB-INF/lib/ directory and have
different configurations per web application. This allows for separate
configurations to run in the same JVM, but with Docker and microservices
and whatnot being so popular, I don't even use that feature anymore myself
and just go with global logging configs per application.
On Fri, 10 Aug 2018 at 04:53, Rajvinder Pal <rajvinder....@gmail.com> wrote:
> Thanks Jochen. Your reply is all i need.
>
> Regards,
> Raj
>
> On Fri, Aug 10, 2018 at 3:09 PM, Jochen Wiedmann <
> jochen.wiedm...@gmail.com>
> wrote:
>
> > Hi,
> >
> > On Fri, Aug 10, 2018 at 10:48 AM Rajvinder Pal <rajvinder....@gmail.com>
> > wrote:
> > >
> > > Hi,
> > >
> > > I have a query regarding log4j2 initialization from external location.
> > Why
> > > cannot i initialize log4j2 by specifying System Property in
> Application
> > > server as
> > >
> > > log4j.configurationFile : file:///d:/log4j2.xml
> > >
> > > and get Logger in Java files.
> > >
> > > Why do i need log4j-web-2.9.1.jar? what extra functionality does this
> jar
> > > provide? I Just want to understand if first way is sufficient for a
> web
> > > application.
> > >
> >
> > as far as I am concerned, there is absolutely no reason, why you
> > shouldn't simply use log4j2-core, and log4j2-api in a web application,
> > like you should do in any other application. There are a few things to
> > consider, though:
> >
> > - Assuming, that you want your log4j configuration per web app: Make
> > sure, that the log4j files are in WEB-INF/lib. Do *not* use the
> > containers libraries, if there are any. And, do *not* add the log4j
> > jars to the containers class path, for example by putting them into
> > <TOMCAT_HOME>/lib, or whatever.
> > - You should use a ServletContextInitializer to add log4j. This could
> > look roughly like the following:
> >
> > private LoggerContext loggerContext;
> > public void contextInitialized(ServletContext pContext) {
> > final String log4jXmlPath = System.getProperty("log4j.
> > configurationFile");
> > final File log4jXmlFile = new File(log4jXmlPath);
> > try (InputStream in = new FileInputStream(log4jXmlFile)) {
> > ConfigurationSource cs = new ConfigurationSource(in,
> > log4jXmlFile);
> > loggerContext = Configurator.initialize(cs,
> > Thread.currentThread.getContextClassLoader());
> > }
> > }
> > public void contextDestroyed(ServletContext pContext) {
> > loggerContext.close();
> > }
> >
> > - It is another matter, how to access the loggerContext to create
> > loggers. In particular, something like this won't work:
> >
> > private static final Logger log = LogManager.getLogger(MyClass);
> >
> > because this cannot access the loggerContext. (That is, perhaps,
> > something that log4j-web does for you. So, this still
> > might be your best option.)
> >
> > My typical approach to work around that problem would be to have
> > loggers injected by Guice, or Spring, and make
> > sure that the respective framework uses the loggerContext when
> > creating those loggers.
> >
> > Jochen
> >
> > ---------------------------------------------------------------------
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> > For additional commands, e-mail: log4j-user-h...@logging.apache.org
> >
> >
>
--
Matt Sicker <boa...@gmail.com>
