Introduction:

I'm trying to get additional fields to log with log4j, and its working but only when I create an appender in code and not in the log4j.properties

Progress:

1. Used this article Adding Conversion Characters to PatternLayout for log4j 1.1.3
2. Made a sample app for log4j 1.2

Problem:

using the properties file it will run but won't use AppServerPatternLayout so the custom fields aren't displayed.

Download Code

customlog.properties

log4j.rootLogger=FATAL
log4j.logger.some.log=INFO,stdout

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=logging.AppServerPatternLayout
log4j.appender.stdout.layout.ConversionPattern=-----------------using log file------------------------%nTime:      %d%nHost:      %h%nServer:    %s%nComponent: %b%nVersion:   %v%nPriority:  %p%nThread Id: %t%nContext:   %x%nMessage:   %m%n

Main.java logging without a log4j properties file

AppServerLoggerFactory factory;
factory = new AppServerLoggerFactory("MyServer", "MyComponent", "1.0");
AppServerLogger.setFactory(factory);
Logger logger = AppServerLogger.getLogger("some.log");
PatternLayout layout = new AppServerPatternLayout( formatString );
logger.addAppender( new ConsoleAppender(layout) );
logger.info("Hello");

Main.java logging with a log4j properties file

PropertyConfigurator.configure("customlog.properties");
AppServerLoggerFactory factory;
factory = new AppServerLoggerFactory("MyServer", "MyComponent", "1.0");
AppServerLogger.setFactory(factory);
Logger logger = AppServerLogger.getLogger("some.log");
logger.info("Hello");

Expected output

----------------using in code appender----------------------
Time:      2009-11-06 12:55:05,785
Host:      M1330
Server:    MyServer
Component: MyComponent
Version:   1.0
Priority:  INFO
Thread Id: main
Context:   
Message:   logging config from code

Actual output

-----------------using log file------------------------
Time:      2009-11-06 12:56:17,983
Host:      
Server:    
Component: 
Version:   
Priority:  INFO
Thread Id: main
Context:   
Message:   logging config from customlog.properties

Solution

Using MDC you can add custom fields like

MDC.put("Version", versionName);
Logger log = LogManager.getLogger("some.log");        
log.info("Hello");

and pull it out in the log4j.properties with a UPPER case X

log4j.appender.stdout.layout.ConversionPattern=%X{Version}