Different Logger in the same class using Log4J

Question

I want specific messages generated from within the same class to be logged separately. So, how can I create 2 different types of loggers within the same class. Currently, the Properties file looks like

log4j.rootCategory=DEBUG, O

# Stdout
log4j.appender.O=org.apache.log4j.ConsoleAppender
log4j.appender.O.layout=org.apache.log4j.PatternLayout
log4j.appender.O.layout.ConversionPattern=[%d{ISO8601}]%5p%6.6r[%t]%x - %C.%M(%F:%L) - %m%n

# File
log4j.appender.MESSAGE=org.apache.log4j.RollingFileAppender
log4j.appender.MESSAGE.File=target/logs/messages.log
# Control the maximum log file size
log4j.appender.MESSAGE.MaxFileSize=1000KB
# Archive log files (one backup file here)
log4j.appender.MESSAGE.MaxBackupIndex=100
log4j.appender.MESSAGE.layout=org.apache.log4j.PatternLayout
log4j.appender.MESSAGE.layout.ConversionPattern=[%d{ISO8601}]%5p%6.6r[%t]%x - %C.%M           (%        F:%    L) - %m%n
log4j.appender.MESSAGE.

log4j.category.failedMessagesLog=INFO, MESSAGE

I'm using the logging in my code as: – /** Logger. */

Logger logger = Logger.getLogger(MyClass.class);
Logger msgLogger = Logger.getLogger("MESSAGE");

---

Upon testing, I get an empty log file (messages.log) created. Any suggestions??

Answer 1

Create two loggers with different names. You can configure them on a per name basis. A simple way to do this is to add a suffix to you class name. e.g.

Log log1 = LogFactory.getLog(getClass().getName()+".log1");
Log log2 = LogFactory.getLog(getClass().getName()+".log2");

in your properties file.

log4j.category.mypackage.myclass.log1=INFO, MESSAGE1
log4j.category.mypackage.myclass.log2=INFO, MESSAGE2

Answer 2

log4j.rootCategory=DEBUG, O

log4j.appender.O=org.apache.log4j.ConsoleAppender
log4j.appender.O.layout=org.apache.log4j.PatternLayout
log4j.appender.O.layout.ConversionPattern=[%d{ISO8601}]%5p%6.6r[%t]%x - %C.%M(%F:%L) - %m%n

log4j.appender.MESSAGE=org.apache.log4j.RollingFileAppender
log4j.appender.MESSAGE.File=target/logs/messages.log
log4j.appender.MESSAGE.MaxFileSize=1000KB
log4j.appender.MESSAGE.MaxBackupIndex=100
log4j.appender.MESSAGE.layout=org.apache.log4j.PatternLayout
log4j.appender.MESSAGE.layout.ConversionPattern=[%d{ISO8601}]%5p%6.6r[%t]%x - %C.%M


log4j.appender.**MESSAGE2**=org.apache.log4j.RollingFileAppender
log4j.appender.**MESSAGE2**.File=target/logs/**messages2**.log
log4j.appender.**MESSAGE2**.MaxFileSize=1000KB
log4j.appender.**MESSAGE2**.MaxBackupIndex=100
log4j.appender.**MESSAGE2**.layout=org.apache.log4j.PatternLayout
log4j.appender.**MESSAGE2**.layout.ConversionPattern=[%d{ISO8601}]%5p%6.6r[%t]%x - %C.%M    

log4j.category.failedMessagesLog=INFO, MESSAGE , **MESSAGE2**

"failedMessagesLog" is the java file to which appender (INFO,MESSAGE, MESSAGE1) is applied. I have just reused existing RollingFileAppender. you can use any other appender ( like fileAppender).

You should use the right Class name Logger logger = Logger.getLogger(MyClass.class) should be changed to private static final Logger log = Logger.getLogger( **failedMessagesLog.class** );

Make sure you are using log4j's logging ie

import **org.apache.log4j.Logger**;