第8章图形用户界面设计2013-2014祥解.ppt

* 例8-21菜单实例 import javax.swing.*; import java.awt.event.*; import java.awt.*; public class MyMenu extends JFrame{ private JLabel lb1; private JMenu col,ext; private JMenuBar mb; private JMenuItem gre,yel,blu,clo; public MyMenu(){ super(MyMune); Container c=getContentPane(); mb=new JMenuBar(); col=new JMenu(color); ext=new JMenu(exit); gre=new JMenuItem(green); yel=new JMenuItem(yellow); blu=new JMenuItem(blue); clo=new JMenuItem(close window); * gre.addActionListener(new HandLer1()); yel.addActionListener(new HandLer1()); blu.addActionListener(new HandLer1()); clo.addActionListener(new HandLer1()); mb.add(col); mb.add(ext); col.add(gre); col.add(yel); col.add(blu); ext.add(clo); setJMenuBar(mb); lb1=new JLabel(Menu Example); c.add(lb1); setSize(200,150); setVisible(true); } * public static void main(String args[]){ MyMenu app=new MyMenu(); } class HandLer1 implements ActionListener{ public void actionPerformed(ActionEvent e){ JMenuItem mi=(JMenuItem)e.getSource(); if(mi==gre) lb1.setForeground(Color.green); if(mi==yel) lb1.setForeground(Color.yellow); if(mi==blu) lb1.setForeground(Color.blue); if (mi==clo) System.exit(0); } } } * 例题示范 编写一个JApplet程序，以鼠标的当前位置为交叉点画一个十字且在交叉点处显示鼠标的当前位置；当鼠标移动时，十字随着鼠标的移动而移动。 import java.awt.event.*;import java.awt.*;import javax.swing.*; public class MoveMouse extends JApplet{ int x,y,d=100; boolean flag=false; Container panel; public void init(){ panel=getContentPane(); panel.addMouseMotionListener(new MouseMotionHandler()); } public void paint(Graphics g){ if(flag){ g.clearRect(0,0,panel.getWidth(),panel.getHeight()); g.drawString((x=+x+,y=+y+),x,y); g.drawLine(x-d,y,x+d,y); g.drawLine(x,y-d,x,y+d); } } * class MouseMotionHandler extends MouseMotionAdapter{ public void mouseMoved(MouseEvent e){ flag=true; x=e.getX(); y=e.getY(); repaint(); } } } * 例题示范 import java.awt.*; import java.aw