CardLayout布局练习（小的图片浏览器）

 /*
 涉及Panel中的图片的加载，还有Frame的关闭的方法， CardLayout（int hgap, int vgap）就会决定卡片面板的大小
 匿名类的使用。。。
 */
 import java.awt.*;
 import java.awt.event.*;
 import javax.swing.*;
 public class CardLayoutDemo extends Frame{
    Panel pCards=new Panel();//卡片面板
    CardLayout Clayout=new CardLayout(120, 50);//设置卡片和面板边界的垂直和水平距离
    public CardLayoutDemo(){
          setLayout(new BorderLayout(100, 20));
          Panel pBtn = new Panel();//按钮面板

            pCards.setLayout(Clayout);
            //pCards.setPreferredSize(new Dimension(30,40));//这句不再起作用了：因为其父类CardLayoutDemo使用的是BorderLayout布局方式，会自动填充
            pCards.setBackground(Color.red);
            pBtn.setBackground(Color.yellow);
        pBtn.setLayout(new FlowLayout(FlowLayout.CENTER, 10, 10));
            pBtn.setPreferredSize(new Dimension(200, 50));

           Button tmpB;
        pBtn.add(tmpB = new Button("第一张"));
              tmpB.addActionListener(new myActionListener());
                tmpB.setActionCommand("first");
        pBtn.add(tmpB = new Button("下一张"));
              tmpB.addActionListener(new myActionListener());
                tmpB.setActionCommand("next");

        pBtn.add(tmpB = new Button("前一张"));
              tmpB.addActionListener(new myActionListener());
                tmpB.setActionCommand("previous");

        pBtn.add(tmpB = new Button("最后一张"));
              tmpB.addActionListener(new myActionListener());
                tmpB.setActionCommand("last");

        for(int i=1; i<=4; ++i){
               myPanel tmpP;
             pCards.add(""+i, tmpP=new myPanel(i){
                   public void paint(Graphics g){
               g.drawImage(new ImageIcon("zjy"+i+".jpg").getImage(), 20, 0, 300, 400, this);
              }
             });
               tmpP.setBackground(Color.blue);
               //tmpP.setSize(new Dimension(300, 400));//tmpP接受了匿名类对象，可以通过这种方法更改匿名类的属性
               //这里不设置的原因是它的大小由CardLayout(int hgap, int vgap)决定了
          }
            add(pBtn, "North");
            add(pCards, "Center");
    }
    class myActionListener implements ActionListener{
     public void actionPerformed(ActionEvent e){
        String str=e.getActionCommand();
        if(str.equals("first"))
            Clayout.first(pCards);
         else if(str.equals("next"))
            Clayout.next(pCards);
         else if(str.equals("previous"))
            Clayout.previous(pCards);
         else if(str.equals("last"))
            Clayout.last(pCards);
        }
     } 

     public static void main(String args[]){
        CardLayoutDemo myWindow = new CardLayoutDemo();
        myWindow.setSize(new Dimension(600, 600));
        myWindow.setResizable(false);
        myWindow.addWindowListener(new myClosingListener());
        myWindow.setVisible(true);
     }
 }

 class myClosingListener extends WindowAdapter{
    public void windowClosing(WindowEvent e){
       System.exit(0);
    }
 }

 class myPanel extends Panel{
    int i;
    public myPanel(int i){
       this.i=i;
    }
 }