ADFLogger: Using a Custom Formatter Class to Print Log Messages

Based on some posts on the OTN JDeveloper forum this article shows how to implement a custom fdormatter class to use with ADFLogging and how to integrate it with the embedded WLS instance in JDeveloper. Sample workspace for the custom logger is available at the end of the article.
For this post I assume you now your way around java.util.logging. I show how to implement a custom formatter class to format the log messages with more information and a different style. The picture below shows the general java logging model:

General Logging Model

General Logging Model


As the model shows the formatter is used by the log handler which gets a log record and processes it by piping the record through a filter and then through a formatter to finaly pass it to the attached output target. In most cases the output target is a file, a db table, a system log or a stream. For the console logger its most often a stream (e.g. stdout and/or stderr).

A typlical JDev log message from the ConsoleFormatter looks like this:

<AdfcAppInitializer> <loadDebugFacades> ADFc: Initializing ADF Debugger

I’ll change this to:

FINE: 22.09.2011 13:18:17 - de.hahn.blog.popupregion.backingbeans.pageflow.SelectionBean$beaVersion0_39.selectionListenerEmp(SelectionBean.java:92) - 15 - de.hahn.blog.popupregion.backingbeans.pageflow.SelectionBean
  Selected: oracle.jbo.Key[105 ]

The general layout of the log message is

data in [] is customizable, data in {} is printed only if available
level: date time [- threadId] [- class] [- method] [- message] {- throwable.message}
These parameters configure which information to print
       t = thread
       n = logger name
       l = line number; if 'l' is selected 'c' and 'm' are not used
       c = class name
       m = method name

As you see there is more information printed, e.g. source and line number and log level. As this creates long log lines I made this customizable. How the parameters are passed to the logger is shown later.

First of all I implement a class DebugFormatter which extends java.util.logging.SimpleFromatter as this class is an implementation of the abstract class java.util.logging.Formatter the base of all formatter attached to a log handler. The key part of this class is the method

public String format(LogRecord record) {...}

which gets a log record and returns a string of the information which send to the handler for further action. The format method checks the parameters given and returns a string according to them.

To wire things up I modify the logging.xml file which can be reached from the ‘Application Server Navigator’. Right click on the integrated WLS and select ‘Configure Oracle Diagnostic Logging for …’. This will open a nice graphical overview

Logging.xml

Logging.xml


Now I add a new logger by clicking the green ‘+’ sign and specifying the log level and the name of the logger, which is actually the part of the class path the logger reacts on.
Add  Logger

Add Logger


this creates a new line in the logging.xml file looking like
Added Line

Added Line


Next I set up a new log handler in the logging.xml file which uses my DebugLogger class as formatter. Together with the log handler I specify the parameters which configure the output format of the string. The DebugLogger is not used directly, but instead a wrapper class WLSConsoleFormatter used which specifies default parameter set to the DebugFormatter. This way you can omit the parameters in the setup. Below is the resulting log handler entry in the logging.xml file:

        <log_handler name='blog-console-handler'
                     class='de.hahn.blog.consoleformatter.logger.BlogConsoleHandler' level='ALL'
                     encoding='UTF-8'>
            <property name='formatStyle' value='tnlcm'/>
            <property name='formatter'
                      value='de.hahn.blog.consoleformatter.logger.WLSConsoleFormatter'/>
        </log_handler>

To add this you need to change to the source view for the logging.xml file.
Finally I change the added logger to use the new handler

        <logger name='de' level='TRACE:1' useParentHandlers='false'>
            <handler name='blog-console-handler'/>
            <handler name="odl-handler"/>
        </logger>

I have to set the useParentHandlers to false to prevent that the messages get printed multiple times. To be able to analyze the messages with the log analyzer I add the ODL handler too. Now all log messages are printed to the console and to the ODL logger.

Now that the logger are setup in the logging.xml all I need to do is to make the classes available to the WLS instance. For this I build a jar from the project and put the resulting BlogConsoleFormatter.jar in a folder where WLS picks it up while starting. There a a couple of folder, but I choose <ide.system.dir>/DefaultDomain/lib folder. ide.system.dir is also known as the systemfolder of your JDeveloper installation. If you don't know where to find it check this blog. You can either copy the jar into the folder or setup the deployment profile to generate the jar in this folder.

Sample Oiutout

Sample Oiutout

The picture above show a small code sample with the generated output from DebugFormatter. As you see the log lines are marked as links. If you click on such a line you see that you are transfered to the code location of the message.

You can download the source code for the BlogLogConsoleFormatter.zip and a BlogPopupRegion.zip using the ADFLogger to generate messages in different log levels. After downloading the files you need to remove the ‘.doc’ suffix and rename them to ‘.zip’ as the files are normal zip files.
The sample workspaces are developed with JDeveloper 11.1.2.0.0, BlogPopupRegion uses the HR schema as DB connection.

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