Java.util.logging.XMLFormatter - need advise

Question

Hi all,
I have this class which suppose to write some message into the custom log file (in XML). Problem is, after the first time of writing it into the same file, it will append additional XML header :
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE log SYSTEM "logger.dtd">
Worse, it will always append below.
For example, the original XML file contains:
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE log SYSTEM "logger.dtd">
<log>
<record>
  <date>2010-10-20T18:18:33</date>
  <millis>1287569913671</millis>
  <sequence>0</sequence>
  <logger>atm.controller.Log_Controller</logger>
  <level>INFO</level>
  <class>atm.controller.Log_Controller</class>
  <method>writeInfoLog</method>
  <thread>10</thread>
  <message>message inside thia standard data</message>
</record>
</log>when I write additional message into the same file using logger.info("some message"); on the second rounds, it will append additional XML header* info and become like this:
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE log SYSTEM "logger.dtd">
<log>
<record>
  <date>2010-10-20T18:18:33</date>
  <millis>1287569913671</millis>
  <sequence>0</sequence>
  <logger>atm.controller.Log_Controller</logger>
  <level>INFO</level>
  <class>atm.controller.Log_Controller</class>
  <method>writeInfoLog</method>
  <thread>10</thread>
  <message>message inside thia standard data</message>
</record>
</log>
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE log SYSTEM "logger.dtd">
<log>
<record>
  <date>2010-10-20T18:21:25</date>
  <millis>1287570085050</millis>
  <sequence>0</sequence>
  <logger>atm.controller.Log_Controller</logger>
  <level>INFO</level>
  <class>atm.controller.Log_Controller</class>
  <method>writeInfoLog</method>
  <thread>10</thread>
  <message>message inside thia standard data</message>
</record>
</log>--------------------------------------------------
Below is the code.
import java.io.IOException;
import java.util.logging.FileHandler;
import java.util.logging.Logger;
import java.util.logging.XMLFormatter;
public class Log_Controller
    private static Logger logger = Logger.getLogger( Log_Controller.class.getName() );
    private boolean allowAppend = true;
    public Log_Controller()
        try
            XMLFormatter formatterTxt = new XMLFormatter();
            FileHandler fileTxt = new FileHandler( "test.xml", allowAppend );
            fileTxt.setFormatter( formatterTxt );
            logger.addHandler( fileTxt );
        catch ( IOException ioe )
            ioe.printStackTrace();
    public void writeInfoLog( String message )
        logger.info("message inside thia standard data");  //THIS IS THE PART WHERE IT WRITE SOME MESSAGE INTO THE FILE
//        logger.info( message );
}This is something new to me, appreciate if someone can point me what the mistake that I have done.
Thanks thanks.
Edited by: 803699 on 20-Oct-2010 04:15
Edited by: 803699 on 20-Oct-2010 08:45

Answer 1

you cannot append to an xml file using the standard formatter because it makes the log file a "complete xml document" (header and root wrapper tags). if you want to be able to append to an existing xml log file, you will need to roll your own formatter.