menubar.java

这是《Java图形用户界面设计与实例》一书配套的源代码

// MenuBar.java
//Menu bar for the program to hold options

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

public class MenuBar extends JMenuBar implements ActionListener, ItemListener{

    private JMenu jmFile = new JMenu("文件");//Menus
    private JMenu jmBookmarks = new JMenu("标签");
    private JMenu jmHelp = new JMenu("帮助");

    private JMenuItem jmiExit = new JMenuItem("退出");//Items
    private JMenuItem jmiAbout = new JMenuItem("帮助");

    private JMenuItem jmiAddBookmark = new JMenuItem("加入标签");
    private JCheckBoxMenuItem jmiRemoveBookmark = new JCheckBoxMenuItem("移除标签");

    private boolean bRemove = false;


    private BrowserFrame bfRef;

    private BookmarkList bl = new BookmarkList();

    public MenuBar() {
        this(new BrowserFrame());
    }

    public MenuBar(BrowserFrame bf) {//Frame上加人对象与Listener
        bfRef = bf;

        jmFile.add(jmiExit);//Add Items
        jmHelp.add(jmiAbout);
        jmBookmarks.add(jmiAddBookmark);
        jmBookmarks.add(jmiRemoveBookmark);
        jmBookmarks.addSeparator();
        add(jmFile);
        add(jmBookmarks);
        add(jmHelp);
        
        jmiExit.addActionListener(this); //Add listeners so the items
        jmiAbout.addActionListener(this);
        jmiAddBookmark.addActionListener(this);
        jmiRemoveBookmark.addItemListener(this);

        addBookmarks();
    }


    public void addBookmarks() {//将bookmarked的网页加入bookmark的item行列
        for(int x = 0; x < bl.getSize(); x++) {
            JMenuItem jmiBM = new JMenuItem(bl.returnURL(x));

            jmBookmarks.add(jmiBM);
            jmiBM.addActionListener(this);
        }
    }

    public void actionPerformed(ActionEvent e) {//响应Menu动作
        if (e.getSource() == jmiExit)
            System.exit(0);

        else if (e.getSource() == jmiAbout)
            new PopupDialog("Help？", "Help？ 自己动手，丰衣足食！！^_^");

        else if (e.getSource() == jmiAddBookmark) {

            bl.add(bfRef.getCurrentURL());

            addBookmarkItem(bfRef.getCurrentURL());
        }

        else {
    
            if (!bRemove)
                bfRef.setCurrentURL(e.getActionCommand());

            else {

                jmBookmarks.remove((JMenuItem) e.getSource());
                try {
                    bl.remove(e.getActionCommand());
                }

                catch(Exception ex) {
                    new PopupDialog("错误", "移除标签出错！");
                }
            }
        }

    }
    

    public void itemStateChanged(ItemEvent e) {
        if(e.getSource() == jmiRemoveBookmark)
            bRemove = !bRemove;
    }

    public void addBookmarkItem(String s) {

        JMenuItem newItem = new JMenuItem(s);
        newItem.addActionListener(this);
        jmBookmarks.add(newItem);
    }
}