Enabling Logging on Existing Code

The most basic example shows as follows:

ContactListHandler.java
01 package cyber.web.form.test.xcontact;
02 
03 import cyber.web.form.*;
04 import cyber.web.form.tools.VelocityServletHelper;
05 
06 import org.jdom.*;
07 import org.apache.log4j.Logger;
08 import org.apache.velocity.*;
09 import org.apache.velocity.context.Context;
10 
11 /**
12  @author cying
13  *
14  * To change the template for this generated type comment go to
15  * Window>Preferences>Java>Code Generation>Code and Comments
16  */
17 public class ContactListHandler implements XFormHandler
18 {
19     static Logger logger = Logger.getLogger(ContactListHandler.class);

The marked 07 line shows how to import the Logger class.

The marked 19 line shows how to define static per-class logger. This is the most common use of the Logger.

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After you defined the Logger, you will want to use it in your code:

ContactListHandler.java
01     public boolean onXFormEvent(XFormEvent evt)
02     {
03         switch (evt.getEvent())
04         {
05             case XFormEvent.EVENT_PROCESS_FORWARD :
06                 {
07                     if (evt.isForwardAction("delete"))
08                     {
09                         logger.debug("Delete action");
10                         evt.getForm().getElement().detach();
11                         return true;
12                     }