用java编写的记事本，基本功能都实现了啊！

import java.awt.BorderLayout; import java.awt.Container; import java.awt.Font; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.InputEvent; import java.awt.event.KeyAdapter; import java.awt.event.KeyEvent; import java.awt.event.MouseAdapter; import java.awt.event.MouseEvent; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import java.io.BufferedReader; import java.io.BufferedWriter; import java.io.File; import java.io.FileReader; import java.io.FileWriter; import java.io.IOException; import javax.swing.BorderFactory; import javax.swing.JFileChooser; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JMenu; import javax.swing.JMenuBar; import javax.swing.JMenuItem; import javax.swing.JOptionPane; import javax.swing.JPopupMenu; import javax.swing.JScrollPane; import javax.swing.JTextArea; import javax.swing.KeyStroke; import javax.swing.ScrollPaneConstants; import javax.swing.SwingConstants; public class JNotePadUI extends JFrame { private JMenuItem menuOpen; private JMenuItem menuSave; private JMenuItem menuSaveAs; private JMenuItem menuClose; private JMenu editMenu; private JMenuItem menuCut; private JMenuItem menuCopy; private JMenuItem menuPaste; private JMenuItem menuAbout; private JTextArea textArea; private JLabel stateBar; private JFileChooser fileChooser; private JPopupMenu popUpMenu; public JNotePadUI() { super("新建文本文件"); setUpUIComponent(); setUpEventListener(); setVisible(true); } private void setUpUIComponent() { setSize(640, 480); // 菜单栏 JMenuBar menuBar = new JMenuBar(); // 设置「文件」菜单 JMenu fileMenu = new JMenu("文件"); menuOpen = new JMenuItem("打开"); // 快捷键设置 menuOpen.setAccelerator( KeyStroke.getKeyStroke( KeyEvent.VK_O,