demomenu.java

关于学习JAVA中的菜单涉及组件主画框等的小例子源码

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import java.util.*;
import java.awt.geom.*;

public class  DemoMenu 
{
	public static void main(String[] args) 
	{
		//初始化主画框，调整其位置和宽度，使得显示出来的按钮更漂亮
		MainFrame.init("欢迎进入JAVA语言的GUI世界",MainFrame.screenWidth/2,MainFrame.screenHeight/4,MainFrame.screenWidth/3,MainFrame.screenHeight/3,"system");
		DemoMenuCreator demo=new DemoMenuCreator(MainFrame.getContentPane(),MainFrame.getMainFrame());
		//创建演示用的菜单和组件，并将菜单放置在主画框中，组件放置在主画框的内容面板中
		demo.createMenu();
		//启动主画框，并进行演示
		MainFrame.start();
	}
}
class DemoMenuCreator
{
	private Container place;//放置演示组件的容器
	private JFrame topLevelFrame;//放置菜单的顶层容器
	private JTextArea output;//用于输出结果的文本区域
	public DemoMenuCreator(Container place,JFrame topLevelFrame){
	     this.place=place;
		 this.topLevelFrame=topLevelFrame;
	}
	//创建用于演示的组件
	public void createMenu(){
	     //创建一放置在滚动窗格中的文本区域，用来输出用户对菜单的选择结果
		 output=new JTextArea();
		 output.setEditable(false);
		 JScrollPane scrollPane=new JScrollPane(output);
		 place.add(scrollPane,BorderLayout.CENTER);
		 //创建菜单的监听器
		 MenuListener menuListener=new MenuListener();
		 //创建菜单条
		 JMenuBar menuBar=new JMenuBar();
		 topLevelFrame.setJMenuBar(menuBar);//放置在顶层容器中
		 //创建第一个主菜单项
		 JMenu menu= new JMenu("FILE(F)");
		 menu.setMnemonic(KeyEvent.VK_F);
		 menuBar.add(menu);//加入到菜单条
		 //设置第一个主菜单项的第一个子菜单项
		 JMenuItem menuItem=new JMenuItem("新建(N)",new ImageIcon("images/new.gif"));
         menuItem.setMnemonic(KeyEvent.VK_N);
		 //设置此菜单项的加速键为，<ctrl+N>
		 menuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_N,ActionEvent.CTRL_MASK));
         menuItem.addActionListener(menuListener);
		 menu.add(menuItem);//加入到第一个主菜单项中
		 //加入一带子菜单项的菜单项
		 menu.addSeparator();
		 JMenu submenu =new JMenu("发送");
		 menuItem =new JMenuItem("到邮件(M)",KeyEvent.VK_M);
		 //使用<CTL+ALT+M>作为加速键
		 menuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_M,ActionEvent.ALT_MASK|ActionEvent.CTRL_MASK));
         menuItem.addActionListener(menuListener);
		 submenu.add(menuItem);
		 menuItem =new JMenuItem("到桌面快捷方式");
         menuItem.addActionListener(menuListener);
		 submenu.add(menuItem);//加入到子菜单中
		 menu.add(submenu);//将该子菜单加入到第一个主菜单中
		 menu.addSeparator();
		 //为第一个主菜单添加最后一个菜单项
		 menuItem =new JMenuItem("退出");
		 menuItem.addActionListener(menuListener);
		 menuItem.setActionCommand("exit");
		 menu.add(menuItem);
		 //第二个主菜单项
		 menu =new JMenu("帮助(H)");
		 menu.setMnemonic(KeyEvent.VK_H);
		 menuBar.add(menu);
		 menuItem =new JMenuItem("关于```");
		 menuItem.setAccelerator(KeyStroke.getKeyStroke("F1"));
		 menuItem.addActionListener(menuListener);
		 menuItem.setActionCommand("about");
		
		 menu.add(menuItem);
	}
	//监听菜单项的按下动作
	private class MenuListener implements ActionListener 
	{
		public void actionPerformed(ActionEvent e) {
		    JMenuItem source=(JMenuItem)(e.getSource());
			String command =source.getActionCommand();
			if (command.equals("about"))
			{
				MouseTest mousetest=new MouseTest();
				//弹出一窗口显示一些信息
				//JOptionPane.showMessageDialog(MainFrame.getMainFrame(),"面向对象程序设计与JAVA语言V1.0","关于",JOptionPane.WARNING_MESSAGE);

			}else if (command.equals("exit"))
			{
				System.exit(1);//退出整个程序
			}
			else {
			      //其他菜单项则简单地显示用户的选择
				  String s="你选择了菜单项：" + source.getText()+"\n";
				  output.append(s);//添加到输出文本区域中
			}
		}
	}
}
 class MainFrame
{
	//获取显示器的高度和宽度，并置为公有属性，使用者可据此计算画框的位置
	public static final int screenWidth= (int)Toolkit.getDefaultToolkit().getScreenSize().getWidth();
	public static final int screenHeight=(int)Toolkit.getDefaultToolkit().getScreenSize().getHeight();
	//设置主画框的缺省位置和缺省宽度
	private static int width =screenWidth/3;
	private static int height =screenHeight/4;
	private static int startX =screenWidth/3;
	private static int startY =screenHeight/3;
	private static JFrame frame;
	private static JPanel contentPane;
	//使用私有的构造方法可防止使用者创建MainFrame对象，这是工具类的常见做法
	private MainFrame() {}
	//不使用构造方法，而使用INIT（）方法初始化，任何使用类MainFrame的程序必须先调用INIT（）方法
	public static void init(String title) {
	     frame =new JFrame(title);
		 frame.setLocation(new Point(startX,startY));
		 contentPane=(JPanel)frame.getContentPane();
		 contentPane.setPreferredSize(new Dimension(width,height));
		 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	}
    public static void init(String title,int w,int h,int x,int y) {
         width=w;height=h;startX=x;startY=y;
		 init(title);
	}
	//初始化画框并设置画框的观感
	public static void init(String title,int w,int h,int x,int y,String lookAndFeel){
	     try
	     {
	     	if (lookAndFeel.equalsIgnoreCase("windows"))
	     		UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel"); 
	     	else if (lookAndFeel.equalsIgnoreCase("system"))
	     	    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
			else if (lookAndFeel.equalsIgnoreCase("motif"))
			    UIManager.setLookAndFeel("com.sun.java.swing.plaf.motif.MotifLookAndFeel");
			else UIManager.setLookAndFeel(UIManager.getCrossPlatformLookAndFeelClassName());
	     }
	     catch (Exception e)
	     {
	     }
		 width=w;height=h;startX=x;startY=y;
		 init(title);
	}
	//使画框可见，从而启动整个GUI
	public static void start() {frame.pack();frame.setVisible(true);}
	//获取画框的内容窗格，使用者可往此窗格添加所创建的GUI组件
	public static JPanel getContentPane(){return contentPane;}
	//获取画框，使用对话框和菜单的程序要直接基于画框本身
	public static JFrame getMainFrame(){return frame;}



 class  MouseTest
{
	    public MouseTest()
		{
		    MouseFrame frame1=new MouseFrame();
		    frame1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		    frame1.show();
		}
	
}
/**
 A frame containing a panel for testing mouse operations
 */
class MouseFrame extends JFrame
{
	public MouseFrame() 
	{
		setTitle("MouseTest");
		setSize(300,200);
		//add panel to frame
		MousePanel panel=new MousePanel();
		Container contentPane=getContentPane();
		contentPane.add(panel);
	}
	public static final int WIDTH=300;
	public static final int HEIGHT=200;

}
/**
A panel with mouse operations for adding and removing squares
*/
class MousePanel extends JPanel
{

    public MousePanel()
  {
	squares=new ArrayList();
	current=null;
	addMouseListener(new MouseHandler());
	addMouseMotionListener(new MouseMotionHandler());
  }
public void paintComponent(Graphics g) 
{
	super.paintComponent(g);
	Graphics2D g2=(Graphics2D)g;
	//draw all squares
	for (int i=0;i<squares.size() ;i++ )
	    g2.draw((Rectangle2D)squares.get(i));
}
/**
Finds the first square containing a point
@param p a point
@return the index of the first square that contains p
*/
public Rectangle2D find(Point2D p)
{
	for (int i=0;i<squares.size() ;i++ )
	{
		Rectangle2D r=(Rectangle2D)squares.get(i);
		if (r.contains(p)) return r;
		
	}
	return null;
}
/**
   Adds a square to  the collection.
   @param p the center of the square
*/
public void add(Point2D p)
{
	double x=p.getX();
	double y=p.getY();
	current =new Rectangle2D.Double(x-SIDELENGTH/2,y-SIDELENGTH/2,
		SIDELENGTH,SIDELENGTH);
	squares.add(current);
	repaint();
}
/**
   removes a square from the collection.
   @param s the square to remove
 */
public void remove(Rectangle2D s)
{
	if(s==null) return;
	if(s==current) current=null;
	squares.remove(s);
	repaint();
}
private static final int SIDELENGTH=10;
private ArrayList squares;
private Rectangle2D current;
//the square containing the mouse cursor
private class MouseHandler extends MouseAdapter

{
	public void mousePressed(MouseEvent event)
	{
		//add a new square if the cursor isn't inside a square
		current=find(event.getPoint());
		if (current==null)
		   add(event.getPoint());
	}
	public void mouseClicked(MouseEvent event)
	{
		//remove the current square if double clicked
		current =find(event.getPoint());
		if (current !=null && event.getClickCount()>=2)
		    remove(current);
	}
}
private class MouseMotionHandler implements MouseMotionListener
{
	public void mouseMoved(MouseEvent event)
	{
	   //set the mouse cursor to  cross hairs if it is inside a rectangle
	   if (find(event.getPoint())==null)
	      setCursor(Cursor.getDefaultCursor());
	   else 
		  setCursor(Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR));

   }
public void mouseDragged(MouseEvent event)
{
	if (current !=null)
	{
		int x=event.getX();
		int y=event.getY();
		//drag the current rectangle to center it at(x,y)
		current.setFrame(x-SIDELENGTH/2,y-SIDELENGTH/2,
			SIDELENGTH,SIDELENGTH);
		repaint();
	}
  }
 }
}
}