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How do I configure log4j 2.3 with console appender pure programmatically (no configuration files of any format)?
Basically I'm looking for 2.x version of this 1.x code.
In my classes I would then use
private static final Logger logger = LogManager.getLogger(); // // some method logger.debug(someString); Without any configuration I'm (as expected) facing
ERROR StatusLogger No log4j2 configuration file found. Using default configuration: logging only errors to the console.
While usage of configuration files seems to be properly documented, I couldn't find a good example of a bare-bone code-only case.
The closest I got is this article that still uses a dummy file.
Here's my best (though completely unsuccessful) shot:
private static void configureLog4J() { PatternLayout layout = PatternLayout.createDefaultLayout(); ConsoleAppender appender = ConsoleAppender.createDefaultAppenderForLayout(layout); LoggerConfig loggerConfig = new LoggerConfig(); loggerConfig.addAppender(appender, DEBUG, null); } Have I missed something?
If it's still a RTFM case, please point me into the right direction.
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Another approach is to build a new appender and replace the old one with it (most appenders don't support changing their config). This way, all the loggers (and their levels, etc) stay intact. For this to work, I usually add the first appender from code (and not with a config file).
There are many ways to use Log4j2 configuration in you application. Using a configuration file written in XML, JSON, YAML or properties file. Programmatically, by creating a configuration factory and configuration implementation. Programmatically, by calling APIs exposed in the configuration interface.
Apache Log4j 2 is an upgrade to Log4j that provides significant improvements over its predecessor, Log4j 1. x, and provides many of the improvements available in Logback while fixing some inherent problems in Logback's architecture.
package com; import org.apache.logging.log4j.Level; import org.apache.logging.log4j.LogManager; import org.apache.logging.log4j.Logger; import org.apache.logging.log4j.core.Appender; import org.apache.logging.log4j.core.LoggerContext; import org.apache.logging.log4j.core.appender.ConsoleAppender; import org.apache.logging.log4j.core.config.AppenderRef; import org.apache.logging.log4j.core.config.Configuration; import org.apache.logging.log4j.core.config.LoggerConfig; import org.apache.logging.log4j.core.layout.PatternLayout; import java.nio.charset.Charset; public class MyLoggerTest { public static void main(String[] args){ LoggerContext context= (LoggerContext) LogManager.getContext(); Configuration config= context.getConfiguration(); PatternLayout layout= PatternLayout.createLayout("%m%n", null, null, Charset.defaultCharset(),false,false,null,null); Appender appender=ConsoleAppender.createAppender(layout, null, null, "CONSOLE_APPENDER", null, null); appender.start(); AppenderRef ref= AppenderRef.createAppenderRef("CONSOLE_APPENDER",null,null); AppenderRef[] refs = new AppenderRef[] {ref}; LoggerConfig loggerConfig= LoggerConfig.createLogger("false", Level.INFO,"CONSOLE_LOGGER","com",refs,null,null,null); loggerConfig.addAppender(appender,null,null); config.addAppender(appender); config.addLogger("com", loggerConfig); context.updateLoggers(config); Logger logger=LogManager.getContext().getLogger("com"); logger.info("HELLO_WORLD"); } } Not sure if this is what you are looking for. This creates a default configuration and adds a console logger. However, LogManager.getLogger() does not work and using the LogManager.getContext().getLogger() does not allow for logger hierarchy. Honestly i don't recommend the programmatic approach, Log4j2 is allergic to it.
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