Dodatki

Dodatek A Unicode

UNICODE jest standardem kodowania znaków na dwu bajtach, pozwalającym na zdefiniowanie 65536 znaków, bez potrzeby używania różnych stron kodowych dla alfabetów narodowych. Dla kodowania w standardzie ASCII (kodowanie na jednym bajcie) mamy do dyspozycji jedynie 256 znaków i aby uzyskać litery z różnych alfabetów narodowych, trzeba stosować strony kodowe

W poniższej tabeli zestawiono znaki Unicode kodujące polskie litery:

Tabela 6-1 Zestawienie znaków Unicode kodujących polskie litery.

Aby w programie Javy użyć znaków Unicode stosujemy następującą konwencję:

\ukod_znaku

Przykład:

public void paint(Graphics g)
{
	g.drawString("Dzi\u0119kuj\u0119 ",10,10);
}

Powyższa metoda paint() apletu, drukuje na ekranie słowo Dziękuję.

Znaki Unicode są wyœwietlane, jeœli system, w którym uruchamiane są programy stosujące znaki Unicode implementuje kodowanie znaków Unicode. W przypadku, gdy w zbiorze czcionek nie jest dostępny obraz graficzny reprezentujący dany znak, powinien być wyœwietlony automatycznie znak podobny (np. gdy brak litery Œ wyœwietlana jest litera S ).

Uwaga:

Obecnie standard Unicode nie jest jeszcze zaimplementowany we wszystkich systemach operacyjnych i przeglądarkach.

Tabele wszystkich znaków Unicode dostępne są w Internecie pod adresem: http://www.unicode.org/

Dodatek B Zestawienie różnic między AWT 1.0 a AWT 1.1

Button, List,

MenuItem, TextField 

ActionListener 

actionPerformed(ActionEvent) 

Checkbox, 
CheckboxMenuItem
Choice 

ItemListener

itemStateChanged(ItemEvent)

 WINDOW_DESTROY
 WINDOW_EXPOSE
 WINDOW_ICONIFY
 WINDOW_DEICONIFY 

Dialog, Frame 

WindowListener 

windowClosing(WindowEvent) 
windowOpened(WindowEvent) 
windowIconified(WindowEvent)
 windowDeiconified(WindowEvent)
windowClosed(WindowEvent)* 
windowActivated(WindowEvent)*
windowDeactivated(WindowEvent)* 

WINDOW_MOVED 

Dialog, Frame 

ComponentListener 

componentMoved(ComponentEvent)
componentHidden(ComponentEvent)*
componentResized(ComponentEvent)*
componentShown(ComponentEvent) * 

SCROLL_LINE_UP
 SCROLL_LINE_DOWN
 SCROLL_PAGE_UP 
SCROLL_PAGE_DOWN 
SCROLL_ABSOLUTE 
SCROLL_BEGIN 
SCROLL_END 

Scrollbar 

AdjustmentListener 
(lub użyj nowej klasy 
ScrollPanel) 

adjustmentValueChanged(AdjustmentEvent)

LIST_SELECT 
LIST_DESELECT 

Checkbox, 
CheckboxMenuItem 
Choice, List 

ItemListener 

itemStateChanged(ItemEvent) 

MOUSE_DRAG 
/mouseDrag 
MOUSE_MOVE 
/mouseMove 

Canvas, Dialog,
Frame, Panel,
Window 

MouseMotionListener

mouseDragged(MouseEvent) 
mouseMoved(MouseEvent) 

MOUSE_DOWN /mouseDown 
MOUSE_UP /mouseUp 
MOUSE_ENTER 
/mouseEnter 
MOUSE_EXIT /mouseExit 

Canvas, Dialog,
Frame, Panel,
Window 

MouseListener 

mousePressed(MouseEvent)
mouseReleased(MouseEvent)
mouseEntered(MouseEvent)
mouseExited(MouseEvent)
mouseClicked(MouseEvent)*

KEY_PRESS/keyDown 
KEY_RELEASE/keyUp 
KEY_ACTION /keyDown
KEY_ACTION_RELEASE
/keyUp

Component 

KeyListener 

keyPressed(KeyEvent) 
keyReleased(KeyEvent) 
keyTyped(KeyEvent)*

GOT_FOCUS/gotFocus 
LOST_FOCUS/lostFocus 

Component 

FocusListener 

focusGained(FocusEvent) 
focusLost(FocusEvent) 

brak odpowiednika 
w wersji 1.0

ContainerListener 

componentAdded(ContainerEvent) 
componentRemoved(ContainerEvent) 

TextListener 

textValueChanged(TextEvent)

Uwagi:*
        

Tabela 6-2 Tabela konwersji obsługi zdarzeń z wersji AWT 1.0 do 1.1

 Component 

AllowsMultipleSelections 

 List 

 TextArea 

 Component 

 List 

 Container 

 Choice, List, Menu 

 MenuBar 

 Component, Container 

 MenuItem 

 Component, MenuItem 

 Component 

 Polygon 

 Graphics 

 CheckboxGroup 

 Frame 

 Scrollbar 

 Scrollbar 

 Component 

 No replacement. 

 GetVisible 

 Scrollbar 

 Component 

 HandleEvent 

 Component 

 Hide 

 Component 

 TextArea 

 Container 

Component, Polygon, 
Rectangle 

 List 

 Component 

 KeyUp 

 Component 

 Layout 

Component, Container, 
ScrollPane 

 Component, Container 

 Component 

 Component 

 MinimumSize 

 Component, Container, 
TextArea, TextField 

 Component 

 MouseDrag 

 Component 

 MouseEnter 

 Component 

 MouseExit 

 Component 

 MouseMove 

 Component 

 MouseUp 

 Component 

 Move 

 Component, Rectangle 

 Component, Container, 
Window 

 Component, Window 

Component,Container, 
TextArea, TextField 

 TextArea 

 Component, Rectangle 

 Component, Rectangle 

 CheckboxGroup 

 Frame 

 TextField 

 Scrollbar 

 List 

 Scrollbar 

 Component 

 Component 

 Component 

Tabela 6-3 Zestawienie zmian w AWT 1.1 w porównaniu do AWT 1.0

Uwaga: W tabeli tej zestawione są zmienione elementy AWT nie uwzględniono tu nowych elementów AWT 1.1.

Dodatek C Szkielet apletu wielowątkowego

Tworząc nowy aplet w œśrodowisku Visual J++ 1.1 możemy skorzystać ze standardowego szkieletu apletu wielowątkowego, który możemy dowolnie modyfikować. W przedstawionej w poniższym przykładzie wersji apletu, ładowane są obrazki, które będą służyły jako klatki animacji. Po załadowaniu wszystkich obrazków uruchamiany jest aplet.

Ten przykładowy kod, może być przez nas, oczywiœcie, wykorzystany w innych œśrodowiskach programistycznych Javy przy tworzeniu apletów zawierających animacje lub korzystających z wielowątkowoœci.

Przykład 6.1 Szkielet apletu wielowątkowego

//***************************************************************
// MultiAplet.java:	Applet
//***************************************************************
import java.applet.*;
import java.awt.*;
//===============================================================
// Main Class for applet MultiAplet
//===============================================================
public class MultiAplet extends Applet implements Runnable
{
	// THREAD SUPPORT:
	//		m_MultiAplet	is the Thread object for the applet
	//-----------------------------------------------------------
	private Thread	 m_MultiAplet = null;

	// ANIMATION SUPPORT:
	//		m_Graphics		used for storing the applet's Graphics context
	//		m_Images[]		the array of Image objects for the animation
	//		m_nCurrImage	the index of the next image to be displayed
	//		m_ImgWidth		width of each image
	//		m_ImgHeight		height of each image
	//		m_fAllLoaded	indicates whether all images have been loaded
	//		NUM_IMAGES 		number of images used in the animation
	//------------------------------------------------------------
	private Graphics m_Graphics;
	private Image	 m_Images[];
	private int 	 m_nCurrImage;
	private int 	 m_nImgWidth  = 0;
	private int 	 m_nImgHeight = 0;
	private boolean  m_fAllLoaded = false;
	private final int NUM_IMAGES = 18;

	// MultiAplet Class Constructor
	//-----------------------------------------------------------
	public MultiAplet()
	{
		// TODO: Add constructor code here
	}

	// APPLET INFO SUPPORT:
	//		The getAppletInfo() method returns a string describing the 
	// applet's author, copyright date, or miscellaneous information.
	//--------------------------------------------------------------
	public String getAppletInfo()
	{
		return "Name: MultiAplet\r\n" +
			   "Author: Artur Tyloch\r\n" +
			   "Created with Microsoft Visual J++ Version 1.1";
	}
	//The init() method is called by the AWT when an applet is first 
	//loaded or reloaded. Override this method to perform whatever 
	// initialization your applet needs, such as initializing data 
	// structures, loading images or fonts, creating frame windows, 
	// setting the layout manager, or adding UI components.
	//------------------------------------------------------------
	public void init()
	{
		// If you use a ResourceWizard-generated "control creator" 
		// class to arrange controls in your applet, you may want to 
		// call its CreateControls() method from within this method. 
		// Remove the following call to resize() before adding the call 
		// to CreateControls();
		// CreateControls() does its own resizing.
		//----------------------------------------------------------
		resize(320, 240);

		// TODO: Place additional initialization code here
	}

	// Place additional applet clean up code here.  destroy() is 
	// called when when you applet is terminating and being unloaded.
	//-------------------------------------------------------------
	public void destroy()
	{
		// TODO: Place applet cleanup code here
	}

	// ANIMATION SUPPORT:
	//		Draws the next image, if all images are currently loaded
	//-------------------------------------------------------------
	private void displayImage(Graphics g)
	{
		if (!m_fAllLoaded)
			return;

		// Draw Image in center of applet
		//-----------------------------------------------------------
		g.drawImage(m_Images[m_nCurrImage],
				   (size().width - m_nImgWidth)   / 2,
				   (size().height - m_nImgHeight) / 2, null);
	}

	// MultiAplet Paint Handler
	//--------------------------------------------------------------
	public void paint(Graphics g)
	{
		// ANIMATION SUPPORT:
		//		The following code displays a status message until all the
		// images are loaded. Then it calls displayImage to display the 
		// current image.
		//-----------------------------------------------------------
		if (m_fAllLoaded)
		{
			Rectangle r = g.getClipRect();
			
			g.clearRect(r.x, r.y, r.width, r.height);
			displayImage(g);
		}
		else
			g.drawString("Loading images...", 10, 20);

		// TODO: Place additional applet Paint code here
	}

	//		The start() method is called when the page containing the 
	// applet first appears on the screen. The AppletWizard's initial 
	// implementation of this method starts execution of 
	// the applet's thread.
	//----------------------------------------------------------------
	public void start()
	{
		if (m_MultiAplet == null)
		{
			m_MultiAplet = new Thread(this);
			m_MultiAplet.start();
		}
		// TODO: Place additional applet start code here
	}
	
	//		The stop() method is called when the page containing the 
	// applet is no longer on the screen. The AppletWizard's initial 
	// implementation of this method stops execution of 
	// the applet's thread.
	//--------------------------------------------------------------
	public void stop()
	{
		if (m_MultiAplet != null)
		{
			m_MultiAplet.stop();
			m_MultiAplet = null;
		}

		// TODO: Place additional applet stop code here
	}

	// THREAD SUPPORT
	//		The run() method is called when the applet's thread is 
	// started. If your applet performs any ongoing activities without 
	// waiting for user input, the code for implementing that behavior 
	// typically goes here. For example, for an applet that performs 
	// animation, the run() method controls the display of images.
	//----------------------------------------------------------------
	public void run()
	{
		m_nCurrImage = 0;
		
		// If re-entering the page, then the images have already 
		// been loaded.
		// m_fAllLoaded == TRUE.
		//------------------------------------------------------------
		if (!m_fAllLoaded)
		{
			repaint();
			m_Graphics = getGraphics();
			m_Images   = new Image[NUM_IMAGES];

			// Load in all the images
			//---------------------------------------------------------
			MediaTracker tracker = new MediaTracker(this);
			String strImage;

			// For each image in the animation, this method first 
			// constructs a string containing the path to the image file; 
			// then it begins loading the image into the m_Images array.  
			// Note that the call to getImage will return before the 
			// image is completely loaded.
			//---------------------------------------------------------
			for (int i = 1; i <= NUM_IMAGES; i++)
			{
				// Build path to next image
				//-------------------------------------------------------
				strImage = "images/img00" + ((i < 10) ? "0" : "") +
																 i + ".gif";
				m_Images[i-1] = getImage(getDocumentBase(), strImage);

				tracker.addImage(m_Images[i-1], 0);
			}

			// Wait until all images are fully loaded
			//----------------------------------------------------------
			try
			{
				tracker.waitForAll();
				m_fAllLoaded = !tracker.isErrorAny();
			}
			catch (InterruptedException e)
			{
				// TODO: Place exception-handling code here in case an
				//	   InterruptedException is thrown by Thread.sleep(),
				//		 meaning that another thread has interrupted this one
			}
			
			if (!m_fAllLoaded)
			{
				stop();
				m_Graphics.drawString("Error loading images!", 10, 40);
				return;
			}
			

			// Assuming all images are same width and height.
			//---------------------------------------------------------
			m_nImgWidth  = m_Images[0].getWidth(this);
			m_nImgHeight = m_Images[0].getHeight(this);
		}		
		repaint();

		while (true)
		{
			try
			{
				// Draw next image in animation
				//-------------------------------------------------------
				displayImage(m_Graphics);
				m_nCurrImage++;
				if (m_nCurrImage == NUM_IMAGES)
					m_nCurrImage = 0;

				// TODO:  Add additional thread-specific code here
				Thread.sleep(50);
			}
			catch (InterruptedException e)
			{
				// TODO: Place exception-handling code here in case an
				//	   InterruptedException is thrown by Thread.sleep(),
				//		 meaning that another thread has interrupted this one
				stop();
			}
		}
	}
	// TODO: Place additional applet code here
}

Po uruchomieniu tego apletu na ekranie widzimy obracającą się kulę ziemską:

Ilustracja 6-1 Obraz działania wygenerowanego przez Visual J++ 1.1 szkieletu apletu.

Dodatek D Kod apletu z buforowaniem MojRysownik

Opis patrz punkt.

import java.applet.*;
import java.awt.*;
public class MojRysownik extends Applet implements Runnable
{
	private int m_X = 60, m_Y = 50, m_oldX, m_oldY;
	private Thread animWatek;
	private Font font;
	private Graphics buforGraf;
	private Image bufor;
	private Dimension rozmiarBuf, d; 
	public void init()
	{
		d = this.size();
		font = new Font("Arial", Font.BOLD, 20);
		m_oldX=m_X;
		m_oldY=m_Y;
	}
	public void start()
	{
		if (animWatek == null) animWatek = new Thread(this,"Rysownik");
		animWatek.start();
	}
	public void stop()
	{
		if (animWatek != null)	animWatek.stop();
		animWatek=null;
	}
	
	public void run()
	{
		boolean lewo = true;
		while (Thread.currentThread() == animWatek) 
		{
			if (m_X > 110) lewo = true;
			if (m_X < 10) lewo = false;
			if (lewo)
				{	m_X--;	m_Y--;	}
			else
				{	m_X++;	m_Y++;	}
			repaint();
			try {
				Thread.sleep(50);
			} catch (InterruptedException e){
			}
		}
	}
	private void kolka(Graphics g, int x)
	{
		for (int i = 0; i<7; i++ )
			g.drawOval(x+i*21,30,20,20);
	}

	public void paint(Graphics g)
	{	update(g);	}
	public void update(Graphics g) 
	{
		// zmiena d przechowuje rozmiar obszaru rysowania na ekranie: 
		if ( (buforGraf == null)  || (d.width != rozmiarBuf.width)  || (d.height != rozmiarBuf.height) ) 
		{
			rozmiarBuf = d;
			bufor = createImage(d.width, d.height);
			buforGraf = bufor.getGraphics();
		}  
		buforGraf.setFont(font);
		buforGraf.setColor(getBackground());
		buforGraf.fillRect(0, 0, d.width, d.height);
    		buforGraf.setColor(Color.black);
		buforGraf.fillRect(10,50,280,25);
		buforGraf.setColor(Color.white);
		buforGraf.drawString("animacja z buforowaniem", m_X, 20);
		buforGraf.setColor(Color.yellow);
		buforGraf.drawString("autor: arturt tyloch", 40, m_Y);
		buforGraf.setColor(Color.black);
		kolka(buforGraf, m_X);
		g.drawImage(bufor, 0, 0, this);
	}
}

Dodatek E Wersja apletu ZaladujURL

Opis patrz.

import java.applet.*;
import java.awt.*;
import java.awt.event.*;
public class ZaladujURL extends Applet
{
	public void init()
	{
		final Button btnZaladuj = new Button("Zaladuj strone");
		final TextField txtCo = new 
				TextField("http://friko.onet.pl/po/arturt/index.html");
		setLayout(new BorderLayout());	
		add("North",txtCo);
		add("Center",btnZaladuj);
		btnZaladuj.addActionListener(new ActionListener()
				{
					public void actionPerformed(ActionEvent evt) 
 					{
 						if (evt.getSource() == btnZaladuj)
						try
						{
							getAppletContext().showDocument(new 
								java.net.URL(getCodeBase()+"tmp.html"),"_self");
						}
						catch (Exception exc)
						{ 
							exc.printStackTrace(); 
							txtCo.setText("Zly adres");
						}
							
					}
				});				
	}
}