制作一个记事本软件，实现纯文本文件的新建、打开、保存、另存、复制、粘贴、查找、替换、关于等等功能；关闭软件是弹出对话框提示是否把修改保存，根据用户选择更新磁盘文件内容。java直接给出代码

以下是一个简单的记事本软件的Java代码，实现了基本的功能：

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JOptionPane;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.KeyStroke;
import javax.swing.UIManager;
import javax.swing.filechooser.FileNameExtensionFilter;

public class Notepad implements ActionListener, KeyListener {

    private JFrame frame;
    private JTextArea textArea;
    private JFileChooser fileChooser;
    private File currentFile;
    private boolean isModified;

    public Notepad() {
        frame = new JFrame("Notepad");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        textArea = new JTextArea();
        textArea.addKeyListener(this);
        JScrollPane scrollPane = new JScrollPane(textArea);
        frame.getContentPane().add(scrollPane);

        JMenuBar menuBar = new JMenuBar();
        frame.setJMenuBar(menuBar);

        JMenu fileMenu = new JMenu("File");
        fileMenu.setMnemonic(KeyEvent.VK_F);
        menuBar.add(fileMenu);

        JMenuItem newMenuItem = new JMenuItem("New");
        newMenuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_N, ActionEvent.CTRL_MASK));
        newMenuItem.addActionListener(this);
        fileMenu.add(newMenuItem);

        JMenuItem openMenuItem = new JMenuItem("Open...");
        openMenuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_O, ActionEvent.CTRL_MASK));
        openMenuItem.addActionListener(this);
        fileMenu.add(openMenuItem);

        JMenuItem saveMenuItem = new JMenuItem("Save");
        saveMenuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_S, ActionEvent.CTRL_MASK));
        saveMenuItem.addActionListener(this);
        fileMenu.add(saveMenuItem);

        JMenuItem saveAsMenuItem = new JMenuItem("Save As...");
        saveAsMenuItem.addActionListener(this);
        fileMenu.add(saveAsMenuItem);

        JMenuItem exitMenuItem = new JMenuItem("Exit");
        exitMenuItem.addActionListener(this);
        fileMenu.add(exitMenuItem);

        JMenu editMenu = new JMenu("Edit");
        editMenu.setMnemonic(KeyEvent.VK_E);
        menuBar.add(editMenu);

        JMenuItem copyMenuItem = new JMenuItem("Copy");
        copyMenuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_C, ActionEvent.CTRL_MASK));
        copyMenuItem.addActionListener(this);
        editMenu.add(copyMenuItem);

        JMenuItem pasteMenuItem = new JMenuItem("Paste");
        pasteMenuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_V, ActionEvent.CTRL_MASK));
        pasteMenuItem.addActionListener(this);
        editMenu.add(pasteMenuItem);

        JMenuItem findMenuItem = new JMenuItem("Find");
        findMenuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_F, ActionEvent.CTRL_MASK));
        findMenuItem.addActionListener(this);
        editMenu.add(findMenuItem);

        JMenuItem replaceMenuItem = new JMenuItem("Replace");
        replaceMenuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_H, ActionEvent.CTRL_MASK));
        replaceMenuItem.addActionListener(this);
        editMenu.add(replaceMenuItem);

        JMenu helpMenu = new JMenu("Help");
        helpMenu.setMnemonic(KeyEvent.VK_H);
        menuBar.add(helpMenu);

        JMenuItem aboutMenuItem = new JMenuItem("About");
        aboutMenuItem.addActionListener(this);
        helpMenu.add(aboutMenuItem);

        fileChooser = new JFileChooser();
        FileNameExtensionFilter filter = new FileNameExtensionFilter("Text Files", "txt");
        fileChooser.setFileFilter(filter);

        frame.setSize(600, 400);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);

        isModified = false;
    }

    public static void main(String[] args) {
        try {
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        } catch (Exception e) {
            e.printStackTrace();
        }

        EventQueue.invokeLater(new Runnable() {
            public void run() {
                new Notepad();
            }
        });
    }

    public void actionPerformed(ActionEvent e) {
        String command = e.getActionCommand();

        if (command.equals("New")) {
            newFile();
        } else if (command.equals("Open...")) {
            openFile();
        } else if (command.equals("Save")) {
            saveFile();
        } else if (command.equals("Save As...")) {
            saveFileAs();
        } else if (command.equals("Exit")) {
            exit();
        } else if (command.equals("Copy")) {
            textArea.copy();
        } else if (command.equals("Paste")) {
            textArea.paste();
        } else if (command.equals("Find")) {
            find();
        } else if (command.equals("Replace")) {
            replace();
        } else if (command.equals("About")) {
            JOptionPane.showMessageDialog(frame, "Notepad v1.0", "About Notepad", JOptionPane.INFORMATION_MESSAGE);
        }
    }

    public void keyPressed(KeyEvent e) {
        isModified = true;
    }

    public void keyReleased(KeyEvent e) {
    }

    public void keyTyped(KeyEvent e) {
    }

    private void newFile() {
        if (isModified) {
            int result = JOptionPane.showConfirmDialog(frame, "Do you want to save changes?", "Save Changes",
                    JOptionPane.YES_NO_CANCEL_OPTION);
            if (result == JOptionPane.YES_OPTION) {
                saveFile();
            } else if (result == JOptionPane.CANCEL_OPTION) {
                return;
            }
        }

        textArea.setText("");
        currentFile = null;
        isModified = false;
    }

    private void openFile() {
        if (isModified) {
            int result = JOptionPane.showConfirmDialog(frame, "Do you want to save changes?", "Save Changes",
                    JOptionPane.YES_NO_CANCEL_OPTION);
            if (result == JOptionPane.YES_OPTION) {
                saveFile();
            } else if (result == JOptionPane.CANCEL_OPTION) {
                return;
            }
        }

        int result = fileChooser.showOpenDialog(frame);
        if (result == JFileChooser.APPROVE_OPTION) {
            File file = fileChooser.getSelectedFile();
            try {
                BufferedReader reader = new BufferedReader(new FileReader(file));
                String line = null;
                StringBuilder sb = new StringBuilder();
                while ((line = reader.readLine()) != null) {
                    sb.append(line).append("\n");
                }
                reader.close();
                textArea.setText(sb.toString());
                currentFile = file;
                isModified = false;
            } catch (IOException e) {
                JOptionPane.showMessageDialog(frame, "Error opening file: " + e.getMessage(), "Error",
                        JOptionPane.ERROR_MESSAGE);
            }
        }
    }

    private void saveFile() {
        if (currentFile == null) {
            saveFileAs();
        } else {
            try {
                FileWriter writer = new FileWriter(currentFile);
                writer.write(textArea.getText());
                writer.close();
                isModified = false;
            } catch (IOException e) {
                JOptionPane.showMessageDialog(frame, "Error saving file: " + e.getMessage(), "Error",
                        JOptionPane.ERROR_MESSAGE);
            }
        }
    }

    private void saveFileAs() {
        int result = fileChooser.showSaveDialog(frame);
        if (result == JFileChooser.APPROVE_OPTION) {
            File file = fileChooser.getSelectedFile();
            if (file.exists()) {
                int confirmResult = JOptionPane.showConfirmDialog(frame, "File already exists. Overwrite?",
                        "Confirm Overwrite", JOptionPane.YES_NO_OPTION);
                if (confirmResult != JOptionPane.YES_OPTION) {
                    return;
                }
            }
            try {
                FileWriter writer = new FileWriter(file);
                writer.write(textArea.getText());
                writer.close();
                currentFile = file;
                isModified = false;
            } catch (IOException e) {
                JOptionPane.showMessageDialog(frame, "Error saving file: " + e.getMessage(), "Error",
                        JOptionPane.ERROR_MESSAGE);
            }
        }
    }

    private void exit() {
        if (isModified) {
            int result = JOptionPane.showConfirmDialog(frame, "Do you want to save changes?", "Save Changes",
                    JOptionPane.YES_NO_CANCEL_OPTION);
            if (result == JOptionPane.YES_OPTION) {
                saveFile();
            } else if (result == JOptionPane.CANCEL_OPTION) {
                return;
            }
        }
        System.exit(0);
    }

    private void find() {
        String text = JOptionPane.showInputDialog(frame, "Find:");
        if (text != null) {
            String allText = textArea.getText();
            int index = allText.indexOf(text);
            if (index == -1) {
                JOptionPane.showMessageDialog(frame, "Not found.", "Find", JOptionPane.INFORMATION_MESSAGE);
            } else {
                textArea.setCaretPosition(index);
                textArea.setSelectionStart(index);
                textArea.setSelectionEnd(index + text.length());
            }
        }
    }

    private void replace() {
        String findText = JOptionPane.showInputDialog(frame, "Find:");
        if (findText == null) {
            return;
        }
        String replaceText = JOptionPane.showInputDialog(frame, "Replace with:");
        if (replaceText == null) {
            return;
        }
        String allText = textArea.getText();
        int index = allText.indexOf(findText);
        if (index == -1) {
            JOptionPane.showMessageDialog(frame, "Not found.", "Replace", JOptionPane.INFORMATION_MESSAGE);
        } else {
            textArea.setCaretPosition(index);
            textArea.setSelectionStart(index);
            textArea.setSelectionEnd(index + findText.length());
            textArea.replaceSelection(replaceText);
        }
    }

}

该记事本软件使用了Java Swing界面库来创建GUI，并使用了Java IO库来进行文件操作。