Simple Logging - Extended

This is a followup of the Simple Logging blogpost.

It is possible to change the logging.properties file to use a FileHandler. This directs everything to a file, (obviously).

Check reference 3 for a good explanation of the logging.properties file.

Unfortunately the default values of the FileHandler in the default JSE logging.properties⁶ file leaves a lot to be desired.

property	default	comments	mine
limit	50000	50 kilobytes is quite small for a log file	5000000
count	1	this means the total number of files written is 1, so if the log increases beyond 'limit', you lose the old messages as the file is re-initialized	100
append	false	might want to set this to true, to prevent loss of log messages upon restart. Unfortunately, this means you'll have *two* XML files within the log and they need to be separated afterwards.	true

The following Handlers seem to be already available in Java⁴, if you're looking for something different.

I very much like the XMLFormatter. It provides even more information than general logging, and it can be easily post-processed.

JLogViewer

JLogViewer¹ can view the XML logs written to file. I am sure there are other programs that perform the same function, but this is the one I happened to come across.

java -cp jlogviewer_1_0_0d.jar gianluca.utility.LogViewer

Fixing the logs

Unfortunately for me, the logs contain odd characters (because I am writing received data from sockets into the logs) that are not properly handled by jlogviewer.

I was required to remove the special characters from my logs. Found a blog post² on how to remove them.

cat java0.log.0 | tr -d "\013" | tr -d "\001" | tr -d "\000" | tr -d "\017" > sanitized_java.log

Update 17-03-2014: updated the item on appending to existing logs.

References

[1] JLogViewer

http://jlogviewer.sourceforge.net/

[2] Removing special characters in Linux

http://deepupc.wordpress.com/2009/10/28/removing-special-charactersmca-in-vi/

[3] java Logging - Configuration

http://tutorials.jenkov.com/java-logging/configuration.html

[4] javadoc java.util.logging.Handler

http://docs.oracle.com/javase/7/docs/api/java/util/logging/Handler.html

[5] javadoc java.util.logging.LogManager

http://docs.oracle.com/javase/7/docs/api/java/util/logging/LogManager.html

[6] default logging.properties provided by JRE 7

https://gist.github.com/maartenl/9346237