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public void paint (Graphics)
public void paintComponents(Graphics)
public void paintAll (Graphics)
public void repaint ()
public void repaint (long)
public void repaint (int, int, int, int)
public void repaint (long, int, int, int, int)
public void update (Graphics)
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import java.awt.*;
/**
* LazyPanel ÊÇÒ»¸ö³éÏó»ùÀ࣬ËüÌṩ½« Panel ¶ÔÏóµÄÖÃÈë²Ù×÷ÑÓ³Ùµ½
* ʵ¼Ê²é¿´¸ÃÃæ°åʱÔÙ½øÐеŦÄÜ¡£µ±Ê¹Óà CardLayout ºÍÑ¡Ïî¿¨Ãæ°å
* ÊÓͼʱÕâ¸öÀ༫ΪÓÐÓã¬ÒòΪËüÔÊÐí¸ù¾ÝÄúµÄ²Ù×÷¹¹Ôì×ÓÊÓͼ£¬¶ø²»±Ø
* Ò»¿ªÊ¼¾ÍµÈ´ýÈ«²¿¹¹ÔìÍê³É¡£
*
* Èç¹û×ÓÀàÑ¡Ôñ¸²¸ÇÏÂÃæµÄÈÎÒ»¸ö·½·¨£¬ÔòËüÃDZØÐë±£Ö¤±»¸²¸ÇµÄ·½·¨
* Ê×Ïȵ÷Óø¸ÀàµÄ·½·¨¡£ÕâЩ·½·¨ÊÇ£º
*
* public void paint (Graphics)
* public void paintComponents(Graphics)
* public void paintAll (Graphics)
* public void repaint ()
* public void repaint (long)
* public void repaint (int, int, int, int)
* public void repaint (long, int, int, int, int)
* public void update (Graphics)
*
* ÆäÖеÄÿ¸ö·½·¨¶¼È·±£Ê×Ïȹ¹ÔìÃæ°å£¬È»ºó±ã½«µ÷ÓÃת·¢¸ø¸¸Àà¡£
*
* Èç¹ûÄúҪʹÓÃÕâ¸öÀ࣬ÇëÊ×ÏÈ´´½¨ËüµÄÒ»¸ö×ÓÀ࣬Ȼºó¾¡¿ÉÄܵØ
* ½«×ÓÀ๹Ô캯ÊýÖеĴúÂëÒÆµ½ lazyConstructor ·½·¨ÖС£ÏÂÃæÊÇ
* ʹÓà LazyPanel µÄÒ»¸öʾÀý£º
*
*
*
* import java.awt.*;
*
* class BusyPanel extends LazyPanel
* {
* public BusyPanel (int rows, int cols)
* {
* this.rows = rows;
* this.cols = cols;
* }
*
* protected void lazyConstructor()
* {
* setLayout (new GridLayout (rows, cols));
* for (int i = 0; i < rows * cols; ++i)
* {
* add (new Button (Integer.toString (i + startValue)));
* ++startValue;
* }
* }
*
* static private int startValue = 0;
*
* private int rows;
* private int cols;
* }
*
* Äú¿ÉÒÔÕâÑùʹÓÃËü£º
*
* import java.awt.*;
* import java.awt.event.*;
*
* class TestFrame extends Frame
* {
* public TestFrame ()
* {
* setLayout (new BorderLayout ());
* add (nextButton, "South");
*
* framePanel.setLayout (layout);
* for (int i = 0; i < 30; ++i)
* framePanel.add (new BusyPanel (8, 8), "");
* add (framePanel, "Center");
*
* nextButton.addActionListener (
* new ActionListener()
* {
* public void actionPerformed (ActionEvent event)
* {
* layout.next (framePanel);
* }
* }
* );
*
* setSize (400, 300);
* }
*
* private CardLayout layout = new CardLayout();
* private Button nextButton = new Button ("Next Panel");
* private Panel framePanel = new Panel();
*
* static public void main (String args[])
* {
* (new TestFrame()).show();
* }
* }
*
* Òª²é¿´Ê¹Óà LazyPanel µÄÓÅÔ½ÐÔ£¬ÇëÊÔ׎« lazyConstructor() ·½·¨ÖÐ
* µÄ´úÂëÒÆµ½ BusyPanel µÄ¹¹Ô캯ÊýÖУ¬ÖØÐ±àÒë¸ÃÀ࣬Ȼºó»ØÍ·ÔÙ¿´±¾Àý¡£
* Æô¶¯Ê±µÄ¶îÍâÑÓ³Ù¾ÍÊÇ LazyPanel ÀàÒªÏû³ýµÄÎÊÌâ¡£
*
* ÕâÖÖ´¦Àí¶Ô swing ͬÑùÓÐЧ¡£Ö»Ðë¶Ô LazyPanel ÉÔ×÷Ð޸ģ¬ÈÃËü
* À©Õ¹ JPanel£¨¶ø²»ÊÇ Panel£©¼´¿É¡£
*/
public abstract class LazyPanel extends Panel
{
// ÎÒֻϣÍûµ÷Óà lazyConstructor Ò»´Î¡£
private boolean lazyConstructorCalled = false;
// Swing µÄijЩ°æ±¾ÔÚ½«×é¼þÌí¼Óµ½ËüÃǵÄÈÝÆ÷֮ǰ
// µ÷Óà paint() ·½·¨¡£ÎÒÃDz»Ï£ÍûÔÚÏÔʾ×é¼þ֮ǰ
// µ÷ÓÃ lazyConstructor¡£
private boolean isConstructorFinished = false;
/**
* ´´½¨Ò»¸ö LazyPanel¡£
*/
protected LazyPanel ()
{
isConstructorFinished = true;
}
public void paint (Graphics g)
{
callLazyConstructor();
super.paint (g);
}
public void paintAll(Graphics g)
{
callLazyConstructor();
super.paintAll (g);
}
public void paintComponents (Graphics g)
{
callLazyConstructor();
super.paintComponents (g);
}
public void repaint ()
{
callLazyConstructor();
super.repaint();
}
public void repaint (long l)
{
callLazyConstructor();
super.repaint (l);
}
public void repaint (int i1, int i2, int i3, int i4)
{
callLazyConstructor();
super.repaint (i1, i2, i3, i4);
}
public void repaint (long l, int i1, int i2, int i3, int i4)
{
callLazyConstructor();
super.repaint (l, i1, i2, i3, i4);
}
public void update (Graphics g)
{
callLazyConstructor();
super.update (g);
}
/**
* Ç¿ÖÆµ÷ÓÃÔÚ×ÓÀàÖÐʵÏÖµÄ lazyConstructor() ·½·¨¡£
* Èç¹û¶à´Îµ÷ÓÃij¸ö¸ø¶¨¶ÔÏóµÄÕâ¸ö·½·¨£¬Ôò³ýµÚÒ»´Î
* µ÷ÓÃÒÔÍâµÄÈÎºÎÆäËûµ÷Óò»»áÖ´ÐÐÈκβÙ×÷¡£
*/
public synchronized final void callLazyConstructor()
{
// ÒÔÏ´úÂëµÄ´óÖÂ˼ÏëÈçÏÂËùʾ£º
// 1) ¼ì²é¸Ã·½·¨ÊÇ·ñ±»³É¹¦µ÷Óùý¡£
// Èç¹ûÊÇ£¬Ö»·µ»Ø¶ø²»Ö´ÐÐÈκβÙ×÷¡£
//
// 2) ·ñÔò ... µ÷ÓöèÐÔ¹¹Ô캯Êý¡£
// 3) µ÷Óà validate ÒÔʹËùÌí¼ÓµÄÈ«²¿×é¼þ±äΪ¿É¼ûµÄ¡£
// 4) ×¢ÒâÎÒÃÇÒÑÔÚÔËÐеijÌÐò¡£
if ((lazyConstructorCalled == false) && (getParent() != null))
{
lazyConstructor();
lazyConstructorCalled = true;
validate();
}
}
/**
* ÈκÎ×ÓÀà¶¼±ØÐëʵÏÖÕâ¸ö·½·¨¡£±¾Ó¦¸Ã
* ³öÏÖÔÚ×ÓÀ๹Ô캯ÊýÖеĴó¶àÊý×é¼þ´´½¨
* ´úÂ뽫³öÏÖÔÚ´Ë´¦¡£Çë²ÎÔÄÉÏÃæµÄ
* ʾÀý¡£
*/
abstract protected void lazyConstructor ();
}
ʹÓà LazyPanel
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±ðÔÚ lazyConstructor Öз¢³öÒì³£
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Mark Roulo ÊÇ JavaWorld É쵀 Java ¼¼Çɵļ¼Êõе÷Ô±¡£Ëû´Ó 1989 Ä꿪ʼ´ÓÊÂרҵ±à³Ì£¬²¢ÇÒÔÚ Java Éд¦ÓÚ alpha-3 °æÊ±¾Í¿ªÊ¼Ê¹Óà Java¡£ËûÊÇ KLA-Tencor µÄȫְԱ¹¤£¬Ëû²ÎÓ뿪·¢ÁËÒ»ÖÖ 500KLOC¡¢·Ö²¼Ê½¡¢²¢ÐС¢¶à¼ÆËã»úµÄͼÏñ´¦Àí£¨»¹ÓÐÆäËû¹¦ÄÜ£©Ó¦ÓóÌÐò£¬Õû¸ö³ÌÐò¼¸ºõ¶¼ÊÇÓà Java ±àдµÄ¡£
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ÓÐ¹Ø CardLayout µÄÎĵµ×ÊÁÏ£º
http://java.sun.com/products/jdk/1.2/docs/api/java/awt/CardLayout.html
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http://java.sun.com/docs/books/tutorial/uiswing/components/tabbedpane.html