using log4j in an applet

[julia]

Hi,

I wrote an applet which gives log output using log4j. The log output
shall be written to a file. I signed the applet, but I still get an
security exception.
Could anyone help me.
I wrote some posted messages about the same problem, but I couldn't
find an answer to it.

Thanks in advance.

Here the code of my applet:

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.ArrayList;

import javax.swing.JApplet;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

import org.apache.log4j.Logger;

public class WorkingLetterAnimation extends JApplet {
final Logger log = Logger.getLogger(WorkingLetterAnimation.class);
JFrame f = null;

public void init() {
f = new AnimationFrame(this);
f.addKeyListener(new KeyAdapter() {

public void keyPressed(KeyEvent e) {
}

public void keyReleased(KeyEvent e) {
}

public void keyTyped(KeyEvent e) {
log.info("User has pressed a key for confirmation");
}
});
f.show();
}
}

class AnimationFrame extends JFrame implements Runnable {
final Logger log = Logger.getLogger(AnimationFrame.class);
private JButton start;
private JLabel label;
static final int MAX = 30;
private ArrayList letterList;
private Thread runner;
private String characters = "PQ"; //2 characters
private Font font = new Font("Arial", Font.PLAIN, 80);
int x = 10;
int y = font.getSize() - 10;
private boolean started = false;
private int randomNumber;

WorkingLetterAnimation applet = null;

AnimationFrame(WorkingLetterAnimation applet) {
super("Letter Animation");
this.applet = applet;
setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
setResizable(false);
setState(JFrame.NORMAL);
addPropertyChangeListener(new PropertyChangeListener() {
public void propertyChange(PropertyChangeEvent e) {
setState(JFrame.NORMAL);
// if
(e.getPropertyName().equals(JFrame.ICONIFIED)) {
// setState(JFrame.NORMAL);
// }
}
// Boolean b = (Boolean) pce.getNewValue();
// if (b.equals(Boolean.TRUE)) {
// maximizeFrames();
// }

});
Container contentPane = getContentPane();
contentPane.setLayout(new BorderLayout());
start = new JButton("Start animation");
start.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
started = true;
start.setEnabled(false);
log.info("Animation started");
requestFocus(); // only the key events are recorded
start();
}
});
contentPane.add(start, BorderLayout.SOUTH);
DrawingPanel drawingPanel = new DrawingPanel();
contentPane.add(drawingPanel);
drawingPanel.setBackground(Color.white);
contentPane.add(drawingPanel, BorderLayout.CENTER);
setSize(500, 470);
Dimension dim = getToolkit().getScreenSize();
setLocation(
dim.width / 2 - getWidth() / 2,
dim.height / 2 - getHeight() / 2);
}

class DrawingPanel extends JPanel {
Image img = null;

DrawingPanel() {
}

public void paintComponent(Graphics g) {
super.paintComponent(g);
letterList = new ArrayList();
for (int i = 0; i < MAX; i++) {
label = drawLetter(g);
letterList.add(label);
}

}
}

JLabel drawLetter(Graphics g) {
String s = "";
label = new JLabel();
label.setFont(font);
g.setFont(font);

//pause after the last word
if (y < 400) {
int l = (int) (Math.random() * 2);
s = characters.substring(l, l + 1);
label = new JLabel();
label.setLocation(x, y);
label.setSize(x, y);
g.setColor(Color.black);
g.drawString(s, x, y);
label.setText(s);

}
y += font.getSize();
if (y >= 400) {
y = font.getSize() - 10;
x += font.getSize();
}
return label;
}

public void start() {
if (started) {
if (runner == null) {
runner = new Thread(this);
runner.start();
}
}
}

public void stop() {
if (runner != null) {
runner.stop();
runner = null;
}
}

public void run() {
while (started) {
try {
Thread.sleep(6000);
} catch (Exception e) {
}
randomNumber = (int) (Math.random() * letterList.size());
repaint();
}
}

String randomLetter(String string) {
String letter = null;
if (string.equals("R")) {
letter = "P";
}
if (string.equals("P")) {
letter = "R";
}
if (string.equals("O")) {
letter = "Q";
}
if (string.equals("Q")) {
letter = "O";
}
return letter;
}

public void update(Graphics g) {
if (started) {
g.setFont(font);
g.setColor(Color.white);
JLabel l = (JLabel) letterList.get(randomNumber);
g.fillRect(
l.getX(),
l.getY() - 40,
font.getSize() - 10,
font.getSize() - 10);
String s = randomLetter(l.getText());
log.info(
" letter changed from '" + l.getText() + "' to '" + s
+ "'");
g.setColor(Color.black);
g.drawString(s, l.getX() + 4, l.getY() + 23); //!!!
}
}
}

 

[Ike]

Do you have your applet digitally signed? If your applet uses other jars,
very likely, these other jars must be signed (and with the same digital
signature as your applet is). -Ike

 

[julia]

Yes, I signed a jar. In this jar I put the log4j-1.2.8.jar, the
log4j.properties and all the class-files the applet used. I did the
signing with the help of the Go to Java 2 book. There is a chapter
which explains the signing of applets. I think it has something to do
with log4j, because the log4j.properties file writes in a log file and
not the applet itself. But therefore I signed the
log4j.properties,too.