Posting errors through Log4j in weblogics log file

Question

I am running portlet application , if i want to print all error messages inside weblogic's Log file how can i do it , please explain me full procedure

Answer 1

Step 1. Copy log4j-1.2.9.jar & wllog4j.jar under domain_root/lib folder.
Step 2. Create log4j.xml and drop it under domain_root folder. If you have log4j.xml inside the application(EAR/WAR), I would recommend to move outside EAR/WAR as
changing severity (log level) would require re-deployment. To avoid this, we can move log4j.xml into domain root folder but again the server needs to be bounced.
But there is a fix.
Step 3. Login to weblogic server console. Go to Servers -> Admin Server-> Logging.
Click on advanced mode. Change the logging implementation from JDK to Log4J.
Click save.
Step 4. Activate changes. Re-start the admin server.
This should enable log4j and should write logging into log file mentioned in log4j.xml or properties file.
Hang on! There is a catch here. Say now I want to change the log level from DEBUG into WARN or ERROR.
How do i do?
We go to log4j.xml and change the level.
Now how does this change take into effect? It needs bouncing of the server.
I have given below sample log4j.xml for your reference...
log4j.xml:
<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE log4j:configuration SYSTEM
"log4j.dtd">
<log4j:configuration>
<appender name="CONSOLE" class="org.apache.log4j.ConsoleAppender">
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern"
value="%d [%t] %-5p %c - %m%n"/>
</layout>
</appender>
<appender name="FILE" class="org.apache.log4j.RollingFileAppender">
<param name="File" value="/log/myApp.log"/>
<param name="Append" value="true"/>
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern" value="%d{ISO8601} %t %-5p %c{2} - %m%n"/>
</layout>
</appender>
<logger name="org.apache">
<level value="WARN"/>
</logger>
<logger name="org.springframework">
<level value="WARN"/>
</logger>
<root>
<level value="DEBUG"/>
<appender-ref ref="FILE"/>
<!-- <appender-ref ref="CONSOLE"/> -->
</root>
</log4j:configuration>
I have disabled log4j to write int
I Followed all these steps , but finally i am getting an empty file myApp.log at specified destination , i want all log messages inside that file when WEBLOGIC starts , so what needs to be done for that