Re: log4j configuration and Applets

From:
"Richard Maher" <maher_rj@hotspamnotmail.com>
Newsgroups:
comp.lang.java.programmer
Date:
Mon, 8 Jun 2009 19:17:53 +0800
Message-ID:
<h0iru1$drh$1@news-01.bur.connect.com.au>
Hi Arne,

"Arne Vajh?j" <arne@vajhoej.dk> wrote in message
news:4a2c1b2b$0$90263$14726298@news.sunsite.dk...

Richard Maher wrote:

I need to do some logging from my Applet with varying levels of

verbosity

and log4j looked like the most likely, best-of-breed, widley used,

option

available for the right price. (The Applet is unsigned so a Console

Appender

to System.out is all I require and have available)

So I downloaded log4j-1_2_15.jar and included it with my HTML <object>

and

everything looked ok, but when the Applet loaded it was now instructing

the

browser to look for a log4j.xml or log4j.conf file. I thought I was
good-to-code with the default configuration options (plus runtime
configuration of the logging level [info,debug,fatal, etc]) but I was

happy

to stick a minimal XML file where the browser could find it. (See below)

What I don't like about it now is it's asking for all sorts of
infrastructure bloat to be resolved and sent down the line: -

T3$APPLET_ROOT:[000000.APPLETS.META-INF.SERVICES]

JAVAX^.XML^.PARSERS.DOCUMENTBUILDERFACTORY

T3$APPLET_ROOT:[000000.APPLETS.ORG.APACHE.LOG4J]

CONSOLEAPPENDERBEANINFO.CLASS
WRITERAPPENDERBEANINFO.CLASS
APPENDERSKELETONBEANINFO.CLASS
PATTERNLAYOUTBEANINFO.CLASS
LAYOUTBEANINFO.CLASS

T3$APPLET_ROOT:[000000.APPLETS.JAVA.LANG]

OBJECTBEANINFO.CLASS

I guess I'm asking why these classes (if needed) aren't in the JAR file
already and just home much "baggage" does log4j need?

Is there a "minimalist" switch I can set in the config, or perhaps log4j

is

not the most appropriate tool after all?


I have no idea about where those classes come from. But I do
not think they are needed.

See simple example below, which works for me.

I use log4j.properties instead of log4j.xml, but that should
not matter.

Arne

========================================================

Jar content
-----------

      0 Sun Jun 07 15:48:38 EDT 2009 META-INF/
     97 Sun Jun 07 15:48:38 EDT 2009 META-INF/MANIFEST.MF
    799 Sun Jun 07 15:33:08 EDT 2009 test/LogApplet$1.class
    798 Sun Jun 07 15:33:08 EDT 2009 test/LogApplet$2.class
    798 Sun Jun 07 15:33:08 EDT 2009 test/LogApplet$3.class
    799 Sun Jun 07 15:33:08 EDT 2009 test/LogApplet$4.class
   1302 Sun Jun 07 15:33:08 EDT 2009 test/LogApplet$5.class
   1291 Sun Jun 07 15:33:08 EDT 2009 test/LogApplet$6.class
   2216 Sun Jun 07 15:33:08 EDT 2009 test/LogApplet.class
   2947 Sun Jun 07 15:48:34 EDT 2009 test/GuiAppender.class
    487 Sun Jun 07 15:31:40 EDT 2009 log4j.properties

Manifest
--------

Class-Path: log4j-1.2.9.jar

LogApplet.java
--------------

package test;

import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JApplet;
import javax.swing.JButton;

import org.apache.log4j.ConsoleAppender;
import org.apache.log4j.Level;
import org.apache.log4j.Logger;

public class LogApplet extends JApplet {
     private Logger log = Logger.getLogger(LogApplet.class);
     private JButton debugbtn = new JButton("Log debug");
     private JButton infobtn = new JButton("Log info");
     private JButton warnbtn = new JButton("Log warning");
     private JButton errorbtn = new JButton("Log error");
     private JButton consolebtn = new JButton("Log to console");
     private JButton guibtn = new JButton("Log to GUI");
     private boolean console = false;
     private boolean gui = false;
     public void init() {
         debugbtn.addActionListener(new ActionListener() {
             public void actionPerformed(ActionEvent e) {
                 log.debug("This is a test");
             }
         });
         infobtn.addActionListener(new ActionListener() {
             public void actionPerformed(ActionEvent e) {
                 log.info("This is a test");
             }
         });
         warnbtn.addActionListener(new ActionListener() {
             public void actionPerformed(ActionEvent e) {
                 log.warn("This is a test");
             }
         });
         errorbtn.addActionListener(new ActionListener() {
             public void actionPerformed(ActionEvent e) {
                 log.error("This is a test");
             }
         });
         consolebtn.addActionListener(new ActionListener() {
             public void actionPerformed(ActionEvent e) {
                 console = !console;
                 ConsoleAppender app =
(ConsoleAppender)log.getAppender("console");
                 if(console) {
                     app.setThreshold(Level.DEBUG);
                 } else {
                     app.setThreshold(Level.OFF);
                 }
             }
         });
         guibtn.addActionListener(new ActionListener() {
             public void actionPerformed(ActionEvent e) {
                 gui = !gui;
                 GuiAppender app = (GuiAppender)log.getAppender("gui");
                 if(gui) {
                     app.setThreshold(Level.DEBUG);
                     app.open();
                 } else {
                     app.setThreshold(Level.OFF);
                 }
             }
         });
         getContentPane().setLayout(new GridLayout(3,2 ));
         getContentPane().add(debugbtn);
         getContentPane().add(infobtn);
         getContentPane().add(warnbtn);
         getContentPane().add(errorbtn);
         getContentPane().add(consolebtn);
         getContentPane().add(guibtn);

     }
}

GuiAppender.java
----------------

package test;

import java.awt.BorderLayout;
import java.awt.Color;

import javax.swing.JFrame;
import javax.swing.JTextPane;
import javax.swing.text.BadLocationException;
import javax.swing.text.MutableAttributeSet;
import javax.swing.text.StyleConstants;
import javax.swing.text.StyledDocument;

import org.apache.log4j.AppenderSkeleton;
import org.apache.log4j.Level;
import org.apache.log4j.spi.LoggingEvent;

public class GuiAppender extends AppenderSkeleton {
     private JFrame f;
     private JTextPane tp;
     public GuiAppender() {
         f = new JFrame();
         f.setDefaultCloseOperation(JFrame.HIDE_ON_CLOSE);
         //f.setAlwaysOnTop(true);
         tp = new JTextPane();
         f.getContentPane().setLayout(new BorderLayout());
         f.getContentPane().add(tp, BorderLayout.CENTER);
         f.setSize(600, 400);
     }
     private Color LevelToColor(Level lvl) {
         if(lvl.equals(Level.DEBUG)) {
             return Color.GRAY;
         } else if(lvl.equals(Level.INFO)) {
             return Color.GREEN;
         } else if(lvl.equals(Level.WARN)) {
             return Color.YELLOW;
         } else if(lvl.equals(Level.ERROR)) {
             return Color.RED;
         } else if(lvl.equals(Level.FATAL)) {
             return Color.RED;
         } else {
             return Color.BLACK;
         }

     }
     protected void append(LoggingEvent ev) {
         try {
             StyledDocument doc = tp.getStyledDocument();
             MutableAttributeSet attrs = tp.getInputAttributes();
             StyleConstants.setForeground(attrs,
LevelToColor(ev.getLevel()));
             StyleConstants.setBackground(attrs, Color.LIGHT_GRAY);
             doc.insertString(doc.getLength(), getLayout().format(ev),
attrs);
         } catch (BadLocationException e) {
             e.printStackTrace();
         }
     }
     public void open() {
         f.setVisible(true);
     }
     public void close() {
         f.dispose();
     }
     public boolean requiresLayout() {
         return true;
     }
}

log4j.properties
----------------

log4j.category.test.LogApplet = debug, console, gui
log4j.appender.console.threshold = off
log4j.appender.console = org.apache.log4j.ConsoleAppender
log4j.appender.console.layout = org.apache.log4j.PatternLayout
log4j.appender.console.layout.ConversionPattern = %-30c %d %-5p %m%n
log4j.appender.gui.threshold = off
log4j.appender.gui = test.GuiAppender
log4j.appender.gui.layout = org.apache.log4j.PatternLayout
log4j.appender.gui.layout.ConversionPattern = %-30c %d %-5p %m%n


Thanks for the reply.

I'm guessing/hoping that the problem is that I haven't included the
log4j.properties file in the Applet JAR (as it looks like you have done) I
just stuck it in the codebase.

I'll give it a go now and if I don't report back then all's ok, thanks.

Cheers Richard Maher

PS. If anyone can tell me, given that I have a package "tier3Client" that
uses log4j, should the properties file be at the top/root level in the JAR
or under the package tier3Client/log4j.properties then that would save me
time and be welcomed.

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