webpad.java

JNLP sample, from Java.sun.com

        menuItem = menu.add(aboutAction);
        menuItem.addMouseListener(mouseHandler);
        
        return menu;
    }
    
    // Panel which allows for the enabling and disabling of all the actions.
    private JPanel createPanel()  {
	textArea = new JTextArea();
	JScrollPane scrollPane = new JScrollPane(textArea);
        textArea.addMouseListener(new MouseAdapter() {
		    public void mousePressed(MouseEvent e) {
			if(e.isPopupTrigger()) {
			    popup.show(textArea, e.getX(), e.getY());
			}
		    }
		    public void mouseReleased(MouseEvent e) {
			if(e.isPopupTrigger()) {
			    popup.show(textArea, e.getX(), e.getY());
			}
		    }
		});
	
        JPanel panel = new JPanel(new BorderLayout());
        panel.setPreferredSize(new Dimension(450, 200));
        panel.add(scrollPane, BorderLayout.CENTER);
        
        return panel;
    }
    
    // Creates the status bar.
    private JLabel createStatusBar()  {
        status = new JLabel("Ready...");
        status.setBorder(BorderFactory.createEtchedBorder());
	
        return status;
    }
    
    /*
     * This method acts as the Action handler delegate for all the actions.
     * The Cut, Copy and Paste Actions operate on the JTextArea.
     */
    public void actionPerformed(ActionEvent evt)  {
        String command = evt.getActionCommand();
        
        // Compare the action command to the known actions.
        if (command.equals(aboutAction.getActionCommand()))  {
	    // The about action was invoked
	    JOptionPane.showMessageDialog(this, aboutAction.getLongDescription(), aboutAction.getShortDescription(), JOptionPane.INFORMATION_MESSAGE);
        } else if (command.equals(cutAction.getActionCommand())) {
	    ClipboardHandler.toClipboard(textArea.getSelectedText());
	    textArea.replaceSelection("");
        } else if (command.equals(copyAction.getActionCommand())) {
	    ClipboardHandler.toClipboard(textArea.getSelectedText());
        } else if (command.equals(pasteAction.getActionCommand())) {
	    String txt = ClipboardHandler.fromClipboard();
	    textArea.replaceSelection(txt);
        } else if (command.equals(helpAction.getActionCommand())) {
	    HelpHandler.showHelp(evt);
	} else if (command.equals(exitAction.getActionCommand())) {
            saveScratch(textArea.getText());
	    System.exit(0);
	} else if (command.equals(openAction.getActionCommand())) {
	    String t = FileHandler.open();
	    if (t != null) textArea.setText(t);
	} else if (command.equals(saveAction.getActionCommand())) {
	    FileHandler.save(textArea.getText());
	} else if (command.equals(saveAsAction.getActionCommand())) {
	    FileHandler.saveAs(textArea.getText());
	} else if (command.equals(printAction.getActionCommand())) {
	    FileHandler.print(textArea);
	} else if (command.equals(publishAction.getActionCommand())) {
	    WebHandler.publish(textArea.getText());
	} else if (command.equals(showAction.getActionCommand())) {
	    WebHandler.show();
	}
    }


/*
 * This method will check to see if there is anything stored in
 * PersistenceStorage. If so, it will read it. If not, we will
 * just create a new Persistence Storage. This is implemented
 * mainly for the Webpad app to remember/recall what was
 * displayed in the TextArea before the App was exited 
*/

 private void initPersistence()
 {

     long maxSize = 8192;
     long fileSize = 0;
     boolean persExists = true;
     URL url = null;
     BufferedReader br = null;
     String fName = "README";

     try { 
      ps = (PersistenceService)ServiceManager.lookup("javax.jnlp.PersistenceService"); 
      bs = (BasicService)ServiceManager.lookup("javax.jnlp.BasicService"); 
       } catch (UnavailableServiceException e) { 
           ps = null; 
           bs = null; 
       }

    if (ps != null && bs != null) 
    { 
    

    /*
    ** When the app is executed for the first time, there will be no
    ** Persistence Storage existing, so an Exception will be thrown.
    **/


       try
       {

       URL codebase = bs.getCodeBase(); 

       url = new URL(codebase.toString() + "perstest");
       
       fc = ps.get(url); 
       maxSize = fc.getMaxLength(); 
       fileSize = fc.getLength();
       } catch (Exception ee) {

           System.out.println("Exception reading existing Persistence Storage " + url.toString() +": " + ee);

     /*
     ** There will no persistence storage when the app is executed for
     ** for the first time on the client machine.
     */  
           persExists = false;
       }
      
      try 
      { 
     
     /* If there is no persistence storage, open the default README file.
     ** If persistence exists, but there was nothing in the scratch pad
     ** still open the default README file. Deliberately checking for 
     ** length > 1, because in some cases it is writing one byte to the
     ** file even though it is a null character. Maybe due to some bug.
     ** If we had some valid contents in scratch pad, then retrieve
     ** it from Persistence storage and display it.
     */ 
         if (persExists = true && fileSize > 1)
         {
          br = new BufferedReader(new InputStreamReader(fc.getInputStream()));
         }
         else
         {
           System.out.println("Opening default README file");
           br = new BufferedReader(new InputStreamReader(cl.getResource(fName).openStream()));
           fileSize = 4096;
         }
         
          StringBuffer sb = new StringBuffer((int)fileSize);
          String line = br.readLine();
	  while(line != null) {
	    sb.append(line);
	    sb.append("\n");
	    line = br.readLine();
	     }
	    
	  textArea.setText(sb.toString());
	  br.close();
          ps.delete(url);

        } catch (Exception e) {
       
        /*
        ** This exception will be raised when the app is executed
        ** for the first time in ps.delete.
        */   
        System.out.println("Exception thrown when deleting non-existing ps");
        }
       
        try
        { 
        ps.create(url, maxSize);
        fc = ps.get(url);         
        } catch (Exception e) {
                e.printStackTrace();
        }
    }
 }


  /*
  ** This method will be called upon exit to store whatever is in the
 ** scratch pad into the Persistence Storage. Whenever the app is started
 ** next time, the same content will be displayed again.
 **/

  private void saveScratch(String txt)
  {

      try
      { 
        int sizeNeeded = txt.length() * 2;
	if (sizeNeeded  > fc.getMaxLength()) fc.setMaxLength(sizeNeeded);
	BufferedWriter os = new BufferedWriter(new OutputStreamWriter(fc.getOutputStream(false)));
	os.write(txt);
	os.close();
      } catch(Exception e) {
         e.printStackTrace();
      } 

  }
    
    /**
     * This adapter is constructed to handle mouse over component events.
     */
    private class MouseHandler extends MouseAdapter  {
	
	private JLabel label;
	private String oldMsg;
	
	/**
	 * ctor for the adapter.
	 * @param label the JLabel which will recieve value of the
	 *              Action.LONG_DESCRIPTION key.
	 */
	public MouseHandler(JLabel label)  {
	    setLabel(label);
	    oldMsg = label.getText();
	}
	
	public void setLabel(JLabel label)  {
	    this.label = label;
	}
	
	public void mouseEntered(MouseEvent evt)  {
	    if (evt.getSource() instanceof AbstractButton)  {
		AbstractButton button = (AbstractButton)evt.getSource();
		Action action = button.getAction(); // getAction is new in JDK 1.3
		if (action != null)  {
		    oldMsg = label.getText();
		    String message = (String)action.getValue(Action.LONG_DESCRIPTION);
		    label.setText(message);
		}
	    }
	}
	
	public void mouseExited(MouseEvent evt) {
	    label.setText(oldMsg);
	}
    }
    
    /**
     * Main method
     */
    public static void main(String[] args)  {
	WebPad demo = new WebPad();
	demo.pack();
	demo.setVisible(true);
    }
}