Log4j Dynamic Parameter

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 conta开发者_开发技巧ining 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')

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

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