A modification of the image viewer program that logs various events : Log « Language Basics « Java
A modification of the image viewer program that logs various events
/*
This program is a part of the companion code for Core Java 8th ed.
(http://horstmann.com/corejava)
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import java.util.logging.FileHandler;
import java.util.logging.Handler;
import java.util.logging.Level;
import java.util.logging.LogRecord;
import java.util.logging.Logger;
import java.util.logging.StreamHandler;
import javax.swing.ImageIcon;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
/**
* A modification of the image viewer program that logs various events.
* @version 1.02 2007-05-31
* @author Cay Horstmann
*/
public class LoggingImageViewer
{
public static void main(String[] args)
{
if (System.getProperty("java.util.logging.config.class") == null
&& System.getProperty("java.util.logging.config.file") == null)
{
try
{
Logger.getLogger("com.horstmann.corejava").setLevel(Level.ALL);
final int LOG_ROTATION_COUNT = 10;
Handler handler = new FileHandler("%h/LoggingImageViewer.log", 0, LOG_ROTATION_COUNT);
Logger.getLogger("com.horstmann.corejava").addHandler(handler);
}
catch (IOException e)
{
Logger.getLogger("com.horstmann.corejava").log(Level.SEVERE,
"Can't create log file handler", e);
}
}
EventQueue.invokeLater(new Runnable()
{
public void run()
{
Handler windowHandler = new WindowHandler();
windowHandler.setLevel(Level.ALL);
Logger.getLogger("com.horstmann.corejava").addHandler(windowHandler);
JFrame frame = new ImageViewerFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Logger.getLogger("com.horstmann.corejava").fine("Showing frame");
frame.setVisible(true);
}
});
}
}
/**
* The frame that shows the image.
*/
class ImageViewerFrame extends JFrame
{
public ImageViewerFrame()
{
logger.entering("ImageViewerFrame", "<init>");
setTitle("LoggingImageViewer");
setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
// set up menu bar
JMenuBar menuBar = new JMenuBar();
setJMenuBar(menuBar);
JMenu menu = new JMenu("File");
menuBar.add(menu);
JMenuItem openItem = new JMenuItem("Open");
menu.add(openItem);
openItem.addActionListener(new FileOpenListener());
JMenuItem exitItem = new JMenuItem("Exit");
menu.add(exitItem);
exitItem.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent event)
{
logger.fine("Exiting.");
System.exit(0);
}
});
// use a label to display the images
label = new JLabel();
add(label);
logger.exiting("ImageViewerFrame", "<init>");
}
private class FileOpenListener implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
logger.entering("ImageViewerFrame.FileOpenListener", "actionPerformed", event);
// set up file chooser
JFileChooser chooser = new JFileChooser();
chooser.setCurrentDirectory(new File("."));
// accept all files ending with .gif
chooser.setFileFilter(new javax.swing.filechooser.FileFilter()
{
public boolean accept(File f)
{
return f.getName().toLowerCase().endsWith(".gif") || f.isDirectory();
}
public String getDescription()
{
return "GIF Images";
}
});
// show file chooser dialog
int r = chooser.showOpenDialog(ImageViewerFrame.this);
// if image file accepted, set it as icon of the label
if (r == JFileChooser.APPROVE_OPTION)
{
String name = chooser.getSelectedFile().getPath();
logger.log(Level.FINE, "Reading file {0}", name);
label.setIcon(new ImageIcon(name));
}
else logger.fine("File open dialog canceled.");
logger.exiting("ImageViewerFrame.FileOpenListener", "actionPerformed");
}
}
private JLabel label;
private static Logger logger = Logger.getLogger("com.horstmann.corejava");
private static final int DEFAULT_WIDTH = 300;
private static final int DEFAULT_HEIGHT = 400;
}
/**
* A handler for displaying log records in a window.
*/
class WindowHandler extends StreamHandler
{
public WindowHandler()
{
frame = new JFrame();
final JTextArea output = new JTextArea();
output.setEditable(false);
frame.setSize(200, 200);
frame.add(new JScrollPane(output));
frame.setFocusableWindowState(false);
frame.setVisible(true);
setOutputStream(new OutputStream()
{
public void write(int b)
{
} // not called
public void write(byte[] b, int off, int len)
{
output.append(new String(b, off, len));
}
});
}
public void publish(LogRecord record)
{
if (!frame.isVisible()) return;
super.publish(record);
flush();
}
private JFrame frame;
}
