Log4j Dynamic Parameter

Question

Hi. i have a j2ee web application running on spring framework and using log4j for logging. I have this line in my log4j.properties file. this will insert the logs in my database. How do I set a dynamic value in the message part so that I can somehow append the currently logged in user. The bean object containing info for the current user is in the application context.

log4j.appender.dbLog.sql = INSERT INTO LOGGING (log_date, log_level, location, message) VALUES ('%d{yyyy/MM/dd HH:mm:ss}', '%-5p', '%C-%L', '%m')

Answer 1

You want to use the MDC (Mapped diagnostic context). Here's a link about using it with servlets.

Answer 2

I'm not entirely certain on the "application context" vs the location of my "user info" but my web app was using Struts and log4j and I had a similar (but maybe simpler) requirement, I solved it with code like this:

public class LogoutAction extends org.apache.struts.action.Action {

private Log log_db = LogFactory.getLog("mysql");

public ActionForward execute(ActionMapping mapping, ActionForm form,
        HttpServletRequest request, HttpServletResponse response)
        throws Exception {

    log_db.debug("User: "+request.getRemoteUser()+" logged off");
    request.getSession().invalidate();
    your
}

}

And then in my log4j properties file I had an entry like this:

log4j.logger.mysql=DEBUG, mysql
log4j.appender.mysql=org.apache.log4j.jdbc.JDBCAppender
log4j.appender.mysql.layout=org.apache.log4j.PatternLayout
log4j.appender.mysql.URL=jdbc:mysql://localhost:3306/dbname?autoReconnect=true
log4j.appender.mysql.driver=com.mysql.jdbc.Driver
log4j.appender.mysql.user=user
log4j.appender.mysql.password=password
log4j.appender.mysql.sql=INSERT INTO log (Date, Logger, Priority, Message) VALUES ("%d","%c","%p","%m")
enter code here

And then the result was that my my table row would have data like this:

'2010-03-15 21:49:46,514', 'mysql', 'DEBUG', 'User: ben logged off'

I hope this helps