Desktop sharing using ssh tunnel

Share desktop of A to B with C as the hop. You’ll need access to your own server (C).

Execute on A: (assuming 192.168.1.100 is the ip of machine A)

% ssh -R 3390:192.168.1.100:3389 -l username myserver.com
log in and execute
ping 8.8.8.8 -i 5
to prevent the connection from timing out

Execute on B

% ssh -l username myserver.com -L 3391:localhost:3390

This means that you will be able to connect at localhost:3391 from your home computer and everything will be forwarded to myserver.com:3390.

Point your remote desktop connection to localhost:3391

cropped-DSC_0066-1024x477

Hibernate 4 Integrator pattern and Spring’s DI

Enabling @Autowired in Hibernate entities.

Create an EventListener that kicks in after a Hibernate LOAD event.  Using AutowireCapableBeanFactory to wire @Autowire’d dependencies.

package be.esus.core.infrastructure.hibernate;

import be.core.architecture.common.locator.SpringLocator;
import org.hibernate.event.spi.PostLoadEvent;
import org.hibernate.event.spi.PostLoadEventListener;
import org.springframework.beans.factory.config.AutowireCapableBeanFactory;

// https://jira.spring.io/browse/SPR-9187
public class MyPostLoadEventListener implements PostLoadEventListener {
   @Override
   public void onPostLoad(PostLoadEvent postLoadEvent) {
      Object entity = postLoadEvent.getEntity();

      AutowireCapableBeanFactory spring = SpringLocator.getApplicationContext().getAutowireCapableBeanFactory();
      spring.autowireBean(entity);
   }
}

(SpringLocator is a simple custom class that is ApplicationContextAware in order to have static access to the ApplicationContext)

Register your new listener in Hibernate’s EventListenerRegistry.

package be.esus.core.infrastructure.hibernate;

import org.hibernate.cfg.Configuration;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.event.service.spi.EventListenerRegistry;
import org.hibernate.event.spi.EventType;
import org.hibernate.integrator.spi.Integrator;
import org.hibernate.metamodel.source.MetadataImplementor;
import org.hibernate.service.spi.SessionFactoryServiceRegistry;
import org.springframework.stereotype.Component;

@Component
public class MyEventListenerIntegrator implements Integrator {

   @Override
   public void integrate(Configuration configuration, SessionFactoryImplementor sessionFactory,
                         SessionFactoryServiceRegistry serviceRegistry) {
      EventListenerRegistry eventListenerRegistry = serviceRegistry.getService( EventListenerRegistry.class );

      eventListenerRegistry.appendListeners(EventType.POST_LOAD, new MyPostLoadEventListener());
   }

   @Override
   public void integrate(MetadataImplementor metadataImplementor,
                         SessionFactoryImplementor sessionFactoryImplementor,
                         SessionFactoryServiceRegistry sessionFactoryServiceRegistry) {

   }

   @Override
   public void disintegrate(SessionFactoryImplementor sessionFactoryImplementor,
                            SessionFactoryServiceRegistry sessionFactoryServiceRegistry) {

   }
}

To register your SPI (see service loader), create
a (text) file called org.hibernate.integrator.spi.Integrator in META-INF/services/ and put the FQCN of your integrator in it:

be.esus.core.infrastructure.hibernate.MyEventListenerIntegrator

Implementing a mouseover effect with a JButton

Add a MouseListener to your JButton and code the desired behaviour in mouseEntered and mouseExited.
This example makes the JButton’s label red when mouse-moving over it.

Main.java:

import java.awt.event.*;
import javax.swing.*;
import java.awt.*;
   
public class Main extends JFrame {
   JList list; 
 
   public Main() {
      getContentPane().setLayout(new FlowLayout());
 
      // following objects are final because they are used
      // in a inner class
      final JButton button = new JButton("OK!");
      button.addMouseListener(new MouseAdapter() {
         Color oldcolor = button.getForeground();
         public void mouseEntered(MouseEvent me) {
            oldcolor = button.getForeground();
            button.setForeground(Color.red); 
         }
         public void mouseExited(MouseEvent me) {
            button.setForeground(oldcolor);
         }
      });
 
      getContentPane().add(button);
 
      addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent event) {
            System.exit(0);   
         }      
      });
 
      setSize(400, 400);
   }
 
   public static void main(String[] args) {
      (new Main()).show();
   }
}

Trapping a drop-down event on a JComboBox

Since JDK1.4, you can add a PopupMenuListener to your JComboBox and receive the events.

Main.java:

import javax.swing.event.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;
import java.awt.*;
 
public class Main extends JFrame { 
   public Main() {
      addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent we) {
            System.exit(1);
         }
      }); 
 
      Vector v = new Vector();
      v.add("first element");
      v.add("second element");
      v.add("third element");
      v.add("fourth element");
      v.add("fifth element");
 
      final JComboBox cb = new JComboBox(v);
      cb.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent ae) {
            System.out.println(cb.getSelectedItem());
         }
      });
 
      cb.addPopupMenuListener(new PopupMenuListener() {
         public void popupMenuCanceled(PopupMenuEvent e) {
            System.out.println("PopupMenuCancel Event");
         }
 
         public void popupMenuWillBecomeVisible(PopupMenuEvent e) {
            System.out.println("popupMenuWillBecomeVisible");
         }
 
         public void popupMenuWillBecomeInvisible(PopupMenuEvent e) {
            System.out.println("popupMenuWillBecomeInvisible");
         }
      });
      getContentPane().setLayout(new FlowLayout(FlowLayout.LEFT, 10, 10));
      getContentPane().add(new JLabel("Select element:"));
      getContentPane().add(cb);
   } 
 
   public static void main(String []args) {
      Main main = new Main();
      main.setVisible(true);
      main.setSize(300, 150);
   }
}

Displaying animated GIFs in a JList

Try this example with the following two images:

import javax.swing.border.*;
import java.awt.image.*;
import javax.swing.*;
import java.util.*;
import java.awt.*;
 
public class Main {
   public static void main(String args[]) {
      JFrame frame = new JFrame("JList Background Demonstration");
 
      JList list = new JList();
 
      String [] imageIcon = new String[] {
         "female.gif", "male.gif"
      };
 
      // create model
      Vector v = new Vector();
      for (int i=0; i<10; i++) {
         ImageIcon ii = new ImageIcon(imageIcon[i % 2]);
         ii.setImageObserver(new AnimatedObserver(list, i));
         v.addElement(ii);
      }
 
      list.setListData(v);
  
      frame.getContentPane().add(BorderLayout.CENTER, list); //new JScrollPane(list));
      frame.setDefaultCloseOperation(3);
      frame.pack();
      frame.setVisible(true);
   }
}
 
class AnimatedObserver implements ImageObserver 
{ 
   JList list; 
   int index; 
 
   public AnimatedObserver(JList list, int index) { 
      this.list = list; 
      this.index = index; 
   }  
 
   public boolean imageUpdate (Image img, int infoflags, int x, int y, int width, int height) {
      if ((infoflags & (FRAMEBITS|ALLBITS)) != 0) { 
         Rectangle rect = list.getCellBounds(index, index); 
         list.repaint(rect); 
      } 
 
      return (infoflags & (ALLBITS|ABORT)) == 0; 
   }
} 

Dynamically removing a separator from a JMenu

Look in the JMenu API for the remove methods!

Main.java:

import javax.swing.event.*;
import java.awt.event.*;
import javax.swing.*;
import java.awt.*;
   
public class Main extends JFrame {
   public Main() {
      getContentPane().setLayout(new FlowLayout());
 
      JMenuBar menuBar = new JMenuBar();
      // used in inner class, so final
      final JMenu menu = new JMenu("Sex");
      JMenuItem menuItem0 = new JMenuItem("female");
      JMenuItem menuItem1 = new JMenuItem("male");
      JMenuItem menuItem2 = new JMenuItem("androgyn");
 
      // add the MenuItems to the Menu 
      menu.add(menuItem0);
      menu.add(menuItem1);
 
      // used in inner class, so final
      final JSeparator jsep = new JSeparator();
      menu.add(jsep);
      menu.add(menuItem2);
   
      menuBar.add(menu);
 
      this.setJMenuBar(menuBar); 
      final JButton button = new JButton("remove menu separator");
      button.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent ae) {
            menu.remove(jsep);
            button.setEnabled(false);
         }
      });
      getContentPane().add(button);
 
      addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent event) {
            System.exit(0);   
         }      
      });
 
      setSize(400, 400);
   }
 
   public static void main(String[] args) {
      (new Main()).show();
   }
}

Changing the orientation of a JTextField, eg. right to left

You can use the method setComponentOrientation defined in the Component class, so
you can invoke it on most Swing components.
It does not seem to work properly using JDK1.2, but does with JDK1.3.

import javax.swing.event.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;
import java.awt.*;
   
public class Main extends JFrame
{
   public Main() throws Exception {
      JTextField tf = new JTextField();
      getContentPane().add(tf);
      pack();

      tf.setComponentOrientation(ComponentOrientation.RIGHT_TO_LEFT);
 
      addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent e) {
            System.exit(0);
         }
      });
   }
 
   public static void main(String args[]) throws Exception {
      Main main = new Main();
      main.show();
   }
}

For international applications, you can determine the orientation using
the Locale:

      Locale arabic = new Locale("ar", "SA");
      jcomponent.setComponentOrientation(ComponentOrientation.getOrientation(arabic));

Creating a multi-colored JLabel

A couple of ways to do this. The easiest being that you can use HTML in labels and hence add the font tag inside your text (see example). Another way is to create a custom extended JLabel component that exposes some methods to set the color of individual characters or ranges or characters and create a custom JLabel UI that takes this extra information to render the JLabel correctly.

Main.java:

import javax.swing.text.*;
import java.awt.event.*;
import javax.swing.*;
import java.text.*;
import java.awt.*;
   
public class Main extends JFrame {
   public Main() {
      getContentPane().setLayout(new FlowLayout());
 
      JLabel label = new JLabel("<html><font color=blue>Colored</font> <font color=yellow>label</font></html>");
 
      getContentPane().add(label);     
 
      addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent event) {
            System.exit(0);   
         }      
      });
 
      setSize(300, 100);
   }
 
   public static void main(String[] args) {
      (new Main()).show();
   }
}

Disabling HTML support in a JLabel

Sometimes, it may be necessary to display html tags inside a JLabel. If the text of an HTML enabled JComponent like JLabel starts with then this text will be rendered as HTML. To prevent this rendering from happening, set the clientproperty html of that JLabel to null.

Main.java:

import javax.swing.plaf.basic.*;
import java.awt.event.*;
import java.awt.font.*; 
import javax.swing.*;
import java.util.*;
import java.text.*;
import java.awt.*;
   
public class Main extends JFrame {
   public Main() {
      getContentPane().setLayout(new FlowLayout());
 
      final JLabel label = new JLabel("<html><h1>Test disable html</h1></html>");
      getContentPane().add(label);
 
      label.putClientProperty("html", null);
  
      addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent event) {
            System.exit(0);   
         }      
      });
 
      pack();
   }
 
   public static void main(String[] args) {
      (new Main()).show();
   }
}

Displaying a dialog window to save files

This following example will use Swings JFileChooser to display a save dialog box and allow the user to make a selection.
It will set the current directory to c: and set the default selection to autoexec.bat. Notice that multiple file selections are not implemented for the current look and feels (see the JFileChooser API).
The method showSaveDialog will block until a file has been selected. It returns APPROVE_OPTION if OK has been clicked, CANCEL_OPTION otherwise.

import java.awt.event.*;
import javax.swing.*;
import java.io.*;
 
public class Main extends JFrame
{
   public static void main(String []args) {
      Main main = new Main();
      main.show();
   }
 
   public Main() {
      JButton fileButton = new JButton("Select File");
      fileButton.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent ae) {
            File file = getFileFromUser();
            if (file != null)
               System.out.println(file.getName());
         }
      });
      getContentPane().add(fileButton);
 
      addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent e) {
            System.exit(0);
         }
      });
 
      pack();
   }
  
   public File getFileFromUser() {
      JFileChooser fc = new JFileChooser();
 
      // use current directory
      fc.setCurrentDirectory(new File("c:\"));
 
      // set default name
      fc.setSelectedFile(new File("autoexec.bat"));
 
      // show dialog for opening files
      int result = fc.showSaveDialog(this);
 
      if (result != fc.APPROVE_OPTION) 
         return null;
       
      return fc.getSelectedFile();
   }
}