panllayout.java

非常好的JAVA学习资料

package layout;

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
class ButtonsPanel extends Panel {
//利用该类将5个按钮依BroderLayout组成一组,以备放入各卡片
   ButtonsPanel(String id) {
      setLayout(new BorderLayout());
      add("Center",new Button(id));
      add("North",new Button(id));
      add("South",new Button(id));
      add("East",new Button(id));
      add("West",new Button(id));
      }
}
public class PanlLayout extends Applet {      
  Button first = new Button("First card"), second = new Button("Second card"),
        third = new Button("Third card");     //定义三个按钮
  Panel cards = new Panel();                //定义一个面板cards
  CardLayout cl=new CardLayout();
  
  public void init() {
setLayout(new BorderLayout());         //设置applet的布局

    Panel p = new Panel();                 //定义一个面板p
    p.setLayout(new FlowLayout());         //面板p的布局
    p.add(first);
    p.add(second);
    p.add(third);                        //面板p中放入三个按钮
    add("North", p);                     //将面板p放在applet显示区域的北方

    cards.setLayout(cl);     //设置面板cards的布局
    cards.add("card1",new ButtonsPanel("in the first card")); 
    cards.add("card2", new ButtonsPanel("in the second card"));
    cards.add("card3",new ButtonsPanel("in the third card")); 
  add("Center", cards);    
 //cards面板中加入三个ButtonsPanel，既三张卡片。放在applet显示区域中间

first.addActionListener(new ActionListenerOfButton ());  
    second.addActionListener(new ActionListenerOfButton ());
    third.addActionListener(new ActionListenerOfButton ());
//设置面板p中按钮的监听者为ActionListenerOfButton类对象
  }

  class ActionListenerOfButton implements ActionListener { 
//ActionListenerOfButton类确定显示哪张卡片
     public void actionPerformed(ActionEvent e){
       Object  source=e.getSource(); 
//用getSource()方法取得事件源，见5.2.2节
       if ( source==first ) cl.first(cards);  
 //若按下first card按钮，显示第一张cards
else if ( source==second ) {cl.first(cards);  cl.next(cards);}
                    //若按下second card按钮，显示第一张cards的下一张。
else if ( source==third ) cl.last(cards); 
//若按下third card按钮，显示最后一张cards
      }
  }
}