popupmenutest.java

JAVA编程百例书中各章节的所有例子的源代码,包括套接字编程

package ch02.section07;

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

/*
 * 这是一个弹出式菜单的例子
 */
public class PopupMenuTest
    extends JFrame
    implements ActionListener, ItemListener {
  JTextArea output;
  JScrollPane scrollPane;
  String newline = "\n";
  JPopupMenu popup;

  public PopupMenuTest() {
    JMenuBar menuBar;
    JMenu menu, submenu;
    JMenuItem menuItem;
    JRadioButtonMenuItem rbMenuItem;
    JCheckBoxMenuItem cbMenuItem;

    addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent e) {
        System.exit(0);
      }
    });
    /*
     * 实现一个Window容器,布局方式为BorderLayout
     */
    Container contentPane = getContentPane();
    output = new JTextArea(5, 30);
    output.setEditable(false);
    scrollPane = new JScrollPane(output);
    contentPane.add(scrollPane, BorderLayout.CENTER);

    //实现一个 menu bar.
    menuBar = new JMenuBar();
    setJMenuBar(menuBar);

    //实现第一个菜单
    menu = new JMenu("A Menu");
    menu.setMnemonic(KeyEvent.VK_A);
    menu.getAccessibleContext().setAccessibleDescription(
        "只有此菜单有菜单选项");
    menuBar.add(menu);
    //一个菜单选项组JMenuItems
    menuItem = new JMenuItem("A text-only menu item", KeyEvent.VK_T);
    menuItem.setAccelerator(KeyStroke.getKeyStroke(
        KeyEvent.VK_1, ActionEvent.ALT_MASK));
    menuItem.getAccessibleContext().setAccessibleDescription(
        "This doesn't really do anything");
    menuItem.addActionListener(this);
    menu.add(menuItem);
    menuItem = new JMenuItem("Both text and icon",
                             new ImageIcon("images/middle.gif"));
    menuItem.setMnemonic(KeyEvent.VK_B);
    menuItem.addActionListener(this);
    menu.add(menuItem);
    menuItem = new JMenuItem(new ImageIcon("images/middle.gif"));
    menuItem.setMnemonic(KeyEvent.VK_D);
    menuItem.addActionListener(this);
    menu.add(menuItem);

    //一个单选按钮组
    menu.addSeparator();
    ButtonGroup group = new ButtonGroup();
    rbMenuItem = new JRadioButtonMenuItem("A radio button menu item");
    rbMenuItem.setSelected(true);
    rbMenuItem.setMnemonic(KeyEvent.VK_R);
    group.add(rbMenuItem);
    rbMenuItem.addActionListener(this);
    menu.add(rbMenuItem);
    rbMenuItem = new JRadioButtonMenuItem("Another one");
    rbMenuItem.setMnemonic(KeyEvent.VK_O);
    group.add(rbMenuItem);
    rbMenuItem.addActionListener(this);
    menu.add(rbMenuItem);

    //一个复选按钮组
    menu.addSeparator();
    cbMenuItem = new JCheckBoxMenuItem("A check box menu item");
    cbMenuItem.setMnemonic(KeyEvent.VK_C);
    cbMenuItem.addItemListener(this);
    menu.add(cbMenuItem);
    cbMenuItem = new JCheckBoxMenuItem("Another one");
    cbMenuItem.setMnemonic(KeyEvent.VK_H);
    cbMenuItem.addItemListener(this);
    menu.add(cbMenuItem);

    //一个子菜单
    menu.addSeparator();
    submenu = new JMenu("A submenu");
    submenu.setMnemonic(KeyEvent.VK_S);

    menuItem = new JMenuItem("An item in the submenu");
    menuItem.setAccelerator(KeyStroke.getKeyStroke(
        KeyEvent.VK_2, ActionEvent.ALT_MASK));
    menuItem.addActionListener(this);
    submenu.add(menuItem);

    menuItem = new JMenuItem("Another item");
    menuItem.addActionListener(this);
    submenu.add(menuItem);
    menu.add(submenu);

    //实现第二个菜单在menu bar中
    menu = new JMenu("Another Menu");
    menu.setMnemonic(KeyEvent.VK_N);
    menu.getAccessibleContext().setAccessibleDescription(
        "This menu does nothing");
    menuBar.add(menu);

    //实现弹出式菜单
    popup = new JPopupMenu();
    menuItem = new JMenuItem("A popup menu item");
    menuItem.addActionListener(this);
    popup.add(menuItem);
    menuItem = new JMenuItem("Another popup menu item");
    menuItem.addActionListener(this);
    popup.add(menuItem);

    //对弹出式菜单注册事件监听
    MouseListener popupListener = new PopupListener();
    output.addMouseListener(popupListener);
    scrollPane.addMouseListener(popupListener);
    menuBar.addMouseListener(popupListener);
  }

  public void actionPerformed(ActionEvent e) {
    JMenuItem source = (JMenuItem) (e.getSource());
    String s = "Action event detected."
        + newline
        + "    Event source: " + source.getText()
        + " (an instance of " + getClassName(source) + ")";
    output.append(s + newline);
  }

  public void itemStateChanged(ItemEvent e) {
    JMenuItem source = (JMenuItem) (e.getSource());
    String s = "Item event detected."
        + newline
        + "    Event source: " + source.getText()
        + " (an instance of " + getClassName(source) + ")"
        + newline
        + "    New state: "
        + ( (e.getStateChange() == ItemEvent.SELECTED) ?
           "selected" : "unselected");
    output.append(s + newline);
  }

  // 返回类名，没有包信息
  protected String getClassName(Object o) {
    String classString = o.getClass().getName();
    int dotIndex = classString.lastIndexOf(".");
    return classString.substring(dotIndex + 1);
  }

  public static void main(String[] args) {
    PopupMenuTest window = new PopupMenuTest();

    window.setTitle("PopupMenuTest");
    window.setSize(450, 260);
    window.setVisible(true);
  }

  class PopupListener
      extends MouseAdapter {
    public void mousePressed(MouseEvent e) {
      maybeShowPopup(e);
    }

    public void mouseReleased(MouseEvent e) {
      maybeShowPopup(e);
    }

    private void maybeShowPopup(MouseEvent e) {
      if (e.isPopupTrigger()) {
        popup.show(e.getComponent(),
                   e.getX(), e.getY());
      }
    }
  }
}