JDeveloper 11g:Using Log4j in ADF business components projects

In case you prefer using  ADF business components in your Model project, the procedure for using log4j logging is almost identical with the EJB way. You might also read an example on using logging within an ADF application module as well.
First, you need to add the library, by double clicking your Model project, as you can see on your left hand side.
Second, you need to create a log4j.properties file within:
C:\...\Model\src

just  like the following:


# Set root logger level to INFO and its only appender to ConsoleOut.
log4j.rootLogger=INFO, ConsoleOut

# ConsoleOut is set to be a ConsoleAppender.
log4j.appender.ConsoleOut=org.apache.log4j.ConsoleAppender

# ConsoleOut uses PatternLayout.
log4j.appender.ConsoleOut.layout=org.apache.log4j.PatternLayout
log4j.appender.ConsoleOut.layout.ConversionPattern=%-5p: [%d] %c{1} - %m%n

log4j.logger.org.apache.jsp=DEBUG
#Addon for
com.sun.faces.level=FINE


Third, you edit your entity object code like that:
...
import org.apache.log4j.Logger;



public class ImagesImpl extends TuhraEntityImpl {
...

    private Logger logger = Logger.getLogger(this.getClass());
  ...

    private void adjustImageUsages(RowSet newImageUsagesBeforePost) {
   ...
      if (logger.isDebugEnabled())
             logger.debug("ImageUsages has been adjusted");
        }
...
}

Finally the message you created appears in the log output window:
INFO : [2010-09-12 09:56:32,593] ImagesImpl - ImageUsages has been adjusted

Would you like to refactor?

Furthermore, if you use logging within multiple entity objects, you could move the declaration code line:

private Logger logger = Logger.getLogger(this.getClass());

to the super class:

package tuhra.model.framework;

import oracle.jbo.server.EntityImpl;
import org.apache.log4j.Logger;

public class TuhraEntityImpl extends EntityImpl {
  protected Logger logger = Logger.getLogger(this.getClass());
}


Upon commit, the logger output appears once more:

INFO : [2010-09-16 10:28:07,288] ImagesImpl - ImageUsages has been adjusted

For dynamic changes of logging levels, one can consult for example:
dynamically-changing-log-level-with-weblogic-log4j-jmx-and-wlst/

Finally, if you need more tips about appenders:
http://www.mobilefish.com/developer/log4j/log4j_quickguide_appenders.html
https://logging.apache.org/log4j/2.x/