Review a simple Java application and log a message via Logback.
App.java
package com.mkyong.test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class App {
private static final Logger log = LoggerFactory.getLogger(App.class);
public static void main(String[] args) {
log.debug("Testing");
}
}
P.S Tested with Logback 1.1.2
1. Problem
A simple logback.xml to log a message to console.
logback.xml
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
<layout class="ch.qos.logback.classic.PatternLayout">
<Pattern>
%d{yyyy-MM-dd HH:mm:ss} [%thread] %-5level %logger{36} - %msg%n
</Pattern>
</layout>
</appender>
<logger name="com.mkyong.test" level="debug">
<appender-ref ref="STDOUT" />
</logger>
<root level="error">
<appender-ref ref="STDOUT" />
</root>
</configuration>
Run above program, the Logback will logs a message twice?
2015-01-25 13:55:21 [main] DEBUG com.mkyong.test.App - Testing
2015-01-25 13:55:21 [main] DEBUG com.mkyong.test.App - Testing
2. Solution
This is caused by the Appenders accumulate. To fix it, add a additivity="false" to the application logger
logback.xml
<logger name="com.mkyong.test" level="debug" additivity="false">
<appender-ref ref="STDOUT" />
</logger>
<root level="error">
<appender-ref ref="STDOUT" />
</root>
Output
2015-01-25 13:58:24 [main] DEBUG com.mkyong.test.App - Testing
This is producing multiple logs: logback.xml
[%X{key}][%X{user}]%date{“yyyy-MM-dd’T’HH:mm:ss,SSSXXX”, Asia/Jakarta} %-5level
%logger{35} – %replace(%msg){‘\n’, ‘ ‘}%nopex%n
Please help.
How can I delete my comment?
God bless you mkyong!
You don’t need to set additivity = false
Just remove STDOUT appender from com.mkyong.test logger
So it will be
logger com.mkyong.test without additivity = false will inherit all ancestors appenders
In this case com.mkyong.test has only one ancestor (root) will inherit STDOUT from root and successfully log into STDOUT with level DEBUG (from com.mkyong.test package)
What would Java developers do without you, man? You’ve saved me so much time on so much crap. Thank you!!!
You already have additivity=false in 1.problem.
fixed, thanks.