Logging into different files based on parameters

[Vishnu Vardhan]

I want to log into two different files based on a value of a varaiable in my Java program

Example : if(value = "abc") log into abcd.txt
else if (value = "xyz") log into xyzz.txt

Can any one help me out please.

Vishnu

[Paul Clapham]

The if-statements seem like a good start. But you have a problem? I can't see what it is. Can you explain a bit more?

[Vishnu Vardhan]

Hi Paul,

Actually my Java program handles requests from two systems. System A and system B. Currently I am logging all the logs into a single file using log4J.

No I want to seperate it. When I process requests from system A they must go to a.log and when I process requests from system B they must go to b.log.

I hope it is clear now.

Thanks
-Vishnu

[Jaikiran Pai]

You can have 2 separate loggers in your java code. Each logger will use a separate appender. To avoid code duplication(of the if/else statements in each class where you are using the logger), i would suggest, you create your own wrapper over the log4j's Logger. Something like:

MyLogger.java {
 
public static org.apache.log4j.Logger getLogger(String className) {
 
//your logic for identifying which system is invoking this logger
if (someUtil.getSysInfo().getSystemName().equals("SystemA") {
//this belongs to systemA, so create and return an logger belonging to systemA
Logger sysALogger = Logger.getLogger("[B]SysA.[/B]" + className);
return sysALogger;
} else {
//belongs to SystemB, so create and return an logger belonging to systemB
Logger sysBLogger = Logger.getLogger("[B]SysB.[/B]" + className);
return sysBLogger;
}
 
}

And the classes using the logger will look like:

SomeClass1.java {
 
//get the instance of logger
private Logger logger = [B]MyLogger.getLogger[/B](this.getClass().getName());

//some method using the logger
public void someMethod1() {

logger.debug("I am in someMethod1");

}
 
}

SomeClass2.java {
 
//get the instance of logger
private Logger logger = [B]MyLogger.getLogger[/B](this.getClass().getName());

//some method using the logger
public void someMethod2() {

logger.debug("I am in someMethod2");

}
 
}

Your log4j.xml will look like:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
 
<!-- ===================================================================== -->
<!--                                                                       -->
<!--  Log4j Configuration                                                  -->
<!--                                                                       -->
<!-- ===================================================================== -->
 
<!-- $Id: log4j.xml,v 1.13.2.8 2003/09/23 14:16:27 slaboure Exp $ -->
 
<!--
   | For more configuration infromation and examples see the Jakarta Log4j
   | owebsite: <a href="http://jakarta.apache.org/log4j" target="_blank" rel="nofollow">http://jakarta.apache.org/log4j</a>
 -->
 
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/" debug="false">
 
   <!-- ================================= -->
   <!-- Preserve messages in a local file -->
   <!-- ================================= -->
 
   <!-- SystemA appender -->
   <appender name="FILE_A" class="org.apache.log4j.FileAppender">
     <param name="File" value="[B]D:/log/mySysALogFile.log[/B]"/>
     <param name="Append" value="false"/>
     
     <layout class="org.apache.log4j.PatternLayout">
       <param name="ConversionPattern" value="%d{ISO8601} %-5p [%c] %m%n"/>
     </layout>    
   </appender>
 
 
   <!-- ================================= -->
   <!-- Preserve messages in a local file -->
   <!-- ================================= -->
 
   <!-- SystemB appender -->
   <appender name="FILE_B" class="org.apache.log4j.FileAppender">
     <param name="File" value="[B]D:/log/mySysBLogFile.log[/B]"/>
     <param name="Append" value="false"/>
     
     <layout class="org.apache.log4j.PatternLayout">
       <param name="ConversionPattern" value="%d{ISO8601} %-5p [%c] %m%n"/>
     </layout>    
   </appender>
 
   
   <!-- ============================== -->
   <!-- Append messages to the console -->
   <!-- ============================== -->
 
   <appender name="CONSOLE" class="org.apache.log4j.ConsoleAppender">
      <param name="Target" value="System.out"/>
      <param name="Threshold" value="INFO"/>
 
      <layout class="org.apache.log4j.PatternLayout">
         <!-- The default pattern: Date Priority [Category] Message\n -->
       <param name="ConversionPattern" value="%d{ISO8601}  %-5p [%c{1}] %m%n"/>
      </layout>
   </appender>
 
   
 
   
   <category name="[B]SysA[/B].myPackage.myClass">
       <priority value="DEBUG" />
       [B]<appender-ref ref="FILE_A"/>[/B]
   </category>
 
   <category name="[B]SysB[/B].myPackage.myClass">
       <priority value="DEBUG" />
       [B]<appender-ref ref="FILE_B"/>[/B]
   </category>
 
 
 
   
   <!-- ======================= -->
   <!-- Setup the Root category -->
   <!-- ======================= -->
 
   <root>
      <appender-ref ref="CONSOLE"/>
   </root>
 
</log4j:configuration> 

The above method looks simple. However, you might want to have a look at some other ways to tackle this, mentioned at Logging Separation and see if they are better suited in your application
[ July 12, 2006: Message edited by: jaikiran pai ]