popupmenuexample.java

java swing 开发代码

//  PopupMenuExample.java
// A simple example of JPopupMenu.  (See MenuElementExample.java for another.)
//
package	jswing.ch14;

import java.awt.event.*;

import javax.swing.*;
import javax.swing.border.*;
import javax.swing.event.*;

public class PopupMenuExample extends JPanel {

    public JPopupMenu popup;

    public PopupMenuExample() {
        popup = new JPopupMenu(); 
        ActionListener menuListener = new ActionListener() {
            public void actionPerformed(ActionEvent event) {
                System.out.println("Popup menu item [" +
                                   event.getActionCommand() + "] was pressed.");
            }
        };
        JMenuItem item;
        popup.add(item = new JMenuItem("Left", new ImageIcon("left.gif")));
        item.setHorizontalTextPosition(JMenuItem.RIGHT);
        item.addActionListener(menuListener);
        popup.add(item = new JMenuItem("Center",
                                             new ImageIcon("center.gif")));
        item.setHorizontalTextPosition(JMenuItem.RIGHT);
        item.addActionListener(menuListener);
        popup.add(item = new JMenuItem("Right", new
                                                  ImageIcon("right.gif")));
        item.setHorizontalTextPosition(JMenuItem.RIGHT);
        item.addActionListener(menuListener);
        popup.add(item = new JMenuItem("Full", new ImageIcon("full.gif")));
        item.setHorizontalTextPosition(JMenuItem.RIGHT);
        item.addActionListener(menuListener);
        popup.addSeparator();
        popup.add(item = new JMenuItem("Settings . . ."));
        item.addActionListener(menuListener);

        popup.setLabel("Justification");
        popup.setBorder(new BevelBorder(BevelBorder.RAISED));
        popup.addPopupMenuListener(new PopupPrintListener());

        addMouseListener(new MousePopupListener());
    }

    // An inner class to check whether mouse events are the popup trigger
    class MousePopupListener extends MouseAdapter {
        public void mousePressed(MouseEvent e) { checkPopup(e); }
        public void mouseClicked(MouseEvent e) { checkPopup(e); }
        public void mouseReleased(MouseEvent e) { checkPopup(e); }

        private void checkPopup(MouseEvent e) {
            if (e.isPopupTrigger()) {
                popup.show(PopupMenuExample.this, e.getX(), e.getY());
            }
        }
    }

    // An inner class to show when popup events occur
    class PopupPrintListener implements PopupMenuListener {
        public void popupMenuWillBecomeVisible(PopupMenuEvent e) {
            System.out.println("Popup menu will be visible!");
        }
        public void popupMenuWillBecomeInvisible(PopupMenuEvent e) {
            System.out.println("Popup menu will be invisible!");
        }
        public void popupMenuCanceled(PopupMenuEvent e) {
            System.out.println("Popup menu is hidden!");
        }
    }

    public static void main(String s[]) {
        JFrame frame = new JFrame("Popup Menu Example");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setContentPane(new PopupMenuExample());
        frame.setSize(300, 300);
        frame.setVisible(true);
    }
}