如果没有找到配置文件，log4j2会发出警告吗？

Question

I have no log4j2 configuration files defined in my classpath. My log messages are still going to the console and I see no warning about a missing configuration.

I am running a servlet based application on Tomcat 7.

I'm trying to figure out how it is getting this configuration?

I am expecting to see the warning in log4j2 like you would see in log4j.

Answer 1

Log4j2 can autoconfigure itself if you do not provide a config file.

Configuration of Log4j 2 can be accomplished in 1 of 4 ways:

1. Through a configuration file written in XML or JSON.
2. Programmatically, by creating a ConfigurationFactory and Configuration implementation.
3. Programmatically, by calling the APIs exposed in the Configuration interface to add components to the default configuration.
4. Programmatically, by calling methods on the internal Logger class.

http://logging.apache.org/log4j/2.x/manual/configuration.html#AutomaticConfiguration

Answer 2

I am using Tomcat. When I removed the log4j2.xml file This is the message that I see when the web server starts:

ERROR StatusLogger No log4j2 configuration file found. Using default configuration: logging only errors to the console.

Since the severity is ERROR, the message is indeed quite visibile.