源码里有注释：

import java.awt.*;import java.awt.event.*;import java.io.*;import javax.swing.*;import javax.swing.text.*;//简单的文本编辑器public class Editor extends JFrame {public JTextPane textPane = new JTextPane(); //文本窗格d，编辑窗口public JFileChooser filechooser = new JFileChooser(); //文件选择器public Editor(){super("简记");Action[] actions=//菜单项的各种功能{new NewAction(),new OpenAction(),new SaveAction(),new CutAction(),new CopyAction(),new PasteAction(),new AboutAction(),new ExitAction(),new HelpAction()};setJMenuBar(createJMenuBar(actions));//根据actions创建菜单栏Container container=getContentPane();container.add(textPane, BorderLayout.CENTER);setSize(1300,1500);setVisible(true);//setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);}private JMenuBar createJMenuBar(Action[] actions)//创建菜单栏的函数{JMenuBar menubar=new JMenuBar();JMenu menuFile=new JMenu("文件(F)");JMenu menuEdit=new JMenu("编辑(E)");JMenu menuAbout=new JMenu("帮助(H)");menuFile.add(new JMenuItem(actions[0]));menuFile.add(new JMenuItem(actions[1]));menuFile.add(new JMenuItem(actions[2]));menuFile.add(new JMenuItem(actions[7]));menuEdit.add(new JMenuItem(actions[3]));menuEdit.add(new JMenuItem(actions[4]));menuEdit.add(new JMenuItem(actions[5]));menuAbout.add(new JMenuItem(actions[6]));menuAbout.add(new JMenuItem(actions[8]));menubar.add(menuFile);menubar.add(menuEdit);menubar.add(menuAbout);return menubar;}class NewAction extends AbstractAction//新建{public NewAction(){super("新建(N) Ctrl+N");}public void actionPerformed(ActionEvent e){textPane.setDocument(new DefaultStyledDocument());}}class OpenAction extends AbstractAction//打开{public OpenAction(){super("打开(O) Ctrl+O");}public void actionPerformed(ActionEvent e){int i=filechooser.showOpenDialog(Editor.this);//显示打开文件对话框if(i==JFileChooser.APPROVE_OPTION)//点击对话框打开选项{File f=filechooser.getSelectedFile();//得到选择的文件try{InputStream is=new FileInputStream(f);textPane.read(is, "d");}catch(Exception ex){ex.printStackTrace();}}}}class SaveAction extends AbstractAction//保存{public SaveAction(){super("保存(S) Ctrl+S");}public void actionPerformed(ActionEvent e){int i=filechooser.showSaveDialog(Editor.this);if(i==JFileChooser.APPROVE_OPTION){File f=filechooser.getSelectedFile();try{FileOutputStream out=new FileOutputStream(f);out.write(textPane.getText().getBytes());}catch(Exception ex){ex.printStackTrace();}}}}class ExitAction extends AbstractAction//退出{public ExitAction(){super("退出(X)");}public void actionPerformed(ActionEvent e){dispose();}}class CutAction extends AbstractAction//剪切{public CutAction(){super("剪切(T) Ctrl+X");}public void actionPerformed(ActionEvent e){textPane.cut();}}class CopyAction extends AbstractAction//复制{public CopyAction(){super("复制(C) Ctrl+C");}public void actionPerformed(ActionEvent e){textPane.copy();}}class PasteAction extends AbstractAction//粘贴{public PasteAction(){super("粘贴(P) Ctrl+V");}public void actionPerformed(ActionEvent e){textPane.paste();}}class AboutAction extends AbstractAction{public AboutAction(){super("关于简记(A)");}public void actionPerformed(ActionEvent e){JOptionPane.showMessageDialog(Editor.this,"实现了记事本的一些基本功能","关于",JOptionPane.PLAIN_MESSAGE);}}class HelpAction extends AbstractAction{public HelpAction(){super("联系开发者");}public void actionPerformed(ActionEvent e){JOptionPane.showMessageDialog(Editor.this,"cpeng2424@gmail.com","开发者邮箱",JOptionPane.PLAIN_MESSAGE);}}public static void main(String[] args){new Editor();}}