Unused log file using FileHandler for two Logger

Question

Hi,
I'm having some troubles with the using java.util.logging classes. To demontrate my problem I prepared the following code:
package org.prove.system;
import java.util.logging.Logger;
public class Child
     private static final Logger LOG = Logger.getLogger("org.prove.system");
     public static void main(String[] args)
          Child.LOG.info("I'm ready too!!!");
package org.prove.logging;
import java.io.IOException;
import java.util.logging.FileHandler;
public class ParentFileHandler extends FileHandler {
     public ParentFileHandler() throws IOException, SecurityException {
          super();
package org.prove.logging;
import java.io.IOException;
import java.util.logging.FileHandler;
public class ChildFileHandler extends FileHandler {
     public ChildFileHandler() throws IOException, SecurityException {
          super();
}and the following is the configuration inside my logging.properties file
# Loggers configuration
org.prove.handlers = org.prove.logging.ParentFileHandler
org.prove.level = ALL
org.prove.useParentHandlers = false
org.prove.system.handlers = org.prove.logging.ChildFileHandler
org.prove.system.level = ALL
org.prove.logging.ParentFileHandler.pattern = %h/logs/Parent.%u.log
org.prove.logging.ParentFileHandler.formatter = java.util.logging.SimpleFormatter
org.prove.logging.ParentFileHandler.append = true
org.prove.logging.ChildFileHandler.pattern = %h/logs/Child.%u.log
org.prove.logging.ChildFileHandler.formatter = java.util.logging.SimpleFormatter
org.prove.logging.ChildFileHandler.append = trueNow, if you try my example you can find, inside the "logs" directory specified in the configuration file, some files:
- Child.0.log, which is the file for the org.prove.logging.ChildFileHandler;
- Parent.0.log, which is the file for the org.prove.logging.ParentFileHandler.
but you can also find:
- Parent.1.log;
- Parent.1.log.lck.
In particular the last two files are generated by the initialization of the org.prove.logging.ParentFileHandler, because inside the method addLogger of the LogManager class, after the initialization of the demanded logger there is a cycle to identify the parent of the logger itself.
Inside that cycle is invoked again the method demandLogger that, if not already initialized, creates the Logger, and after instantiates the handlers of that logger, generating the Parent.1.log and its lock file Parent.1.log.lck. This files are not used and at the end of the execution the lock file is not deleted as the others.
I hope my problem is clear and someone can help me to identify how to resolve it.
Thanks in advance
Alessandro Cristiani

Answer 1

It is not possible to redirect the two different type of logs by using same log level. you have to use to different log levels for both and then in your code you have to mark specifically.
to do this you can use log levels ERROR (for exceptions) and FATAL (for errors).
First define your own logger class that will be using the log4j API's
import org.apache.log4j.Logger;
public class MyLogger {
   static Logger log = Logger.getLogger(MyLogger.class);
   public static logThrowable(Throwable th){
       if(th instanceof Exception) {
          log.error(th.getMessage());
       } else {
           log.fatal(th.getMessage());
}and for your log4j.xml
change the level for your ERROR_FILE to FATAL
in your LogExample
remove:
static Logger log = Logger.getLogger(LogExample.class);change:
}catch(Exception e){
log.error("Exception e");
}to
}catch(Throwable e){
MyLogger.logThrowable(e);
}Hope this helps. Or if you do not want to do in this way then you can also create your own log levels. It is not advisable but you can certainly do that.
Please visit [Log4j Manual|http://logging.apache.org/log4j/1.2/manual.html] for more on this.