写一个有基本功能的java记事本

好的，以下是一个基本功能的 Java 记事本示例代码，包含新建、打开、保存、另存为、复制、粘贴、剪切、查找、替换、字体设置等基本功能：

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

public class JavaNote extends JFrame implements ActionListener {
    private JTextArea textArea = new JTextArea();
    private JScrollPane scrollPane = new JScrollPane(textArea);
    private JFileChooser fileChooser = new JFileChooser();
    private String currentFile = null;

    public JavaNote() {
        setTitle("JavaNote");
        setSize(800, 600);
        setLocationRelativeTo(null);
        setDefaultCloseOperation(EXIT_ON_CLOSE);

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

        JMenu fileMenu = new JMenu("文件");
        menuBar.add(fileMenu);

        JMenuItem newMenuItem = new JMenuItem("新建");
        newMenuItem.addActionListener(this);
        fileMenu.add(newMenuItem);

        JMenuItem openMenuItem = new JMenuItem("打开");
        openMenuItem.addActionListener(this);
        fileMenu.add(openMenuItem);

        JMenuItem saveMenuItem = new JMenuItem("保存");
        saveMenuItem.addActionListener(this);
        fileMenu.add(saveMenuItem);

        JMenuItem saveAsMenuItem = new JMenuItem("另存为");
        saveAsMenuItem.addActionListener(this);
        fileMenu.add(saveAsMenuItem);

        JMenu editMenu = new JMenu("编辑");
        menuBar.add(editMenu);

        JMenuItem cutMenuItem = new JMenuItem("剪切");
        cutMenuItem.addActionListener(this);
        editMenu.add(cutMenuItem);

        JMenuItem copyMenuItem = new JMenuItem("复制");
        copyMenuItem.addActionListener(this);
        editMenu.add(copyMenuItem);

        JMenuItem pasteMenuItem = new JMenuItem("粘贴");
        pasteMenuItem.addActionListener(this);
        editMenu.add(pasteMenuItem);

        JMenuItem findMenuItem = new JMenuItem("查找");
        findMenuItem.addActionListener(this);
        editMenu.add(findMenuItem);

        JMenuItem replaceMenuItem = new JMenuItem("替换");
        replaceMenuItem.addActionListener(this);
        editMenu.add(replaceMenuItem);

        JMenu formatMenu = new JMenu("格式");
        menuBar.add(formatMenu);

        JMenuItem fontMenuItem = new JMenuItem("字体设置");
        fontMenuItem.addActionListener(this);
        formatMenu.add(fontMenuItem);

        add(scrollPane, BorderLayout.CENTER);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        String command = e.getActionCommand();
        switch (command) {
            case "新建":
                newFile();
                break;
            case "打开":
                openFile();
                break;
            case "保存":
                saveFile();
                break;
            case "另存为":
                saveAsFile();
                break;
            case "复制":
                textArea.copy();
                break;
            case "粘贴":
                textArea.paste();
                break;
            case "剪切":
                textArea.cut();
                break;
            case "查找":
                find();
                break;
            case "替换":
                replace();
                break;
            case "字体设置":
                setFont();
                break;
            default:
                break;
        }
    }

    private void newFile() {
        if (textArea.getText().length() > 0) {
            int result = JOptionPane.showConfirmDialog(this, "是否保存当前文件？", "提示", JOptionPane.YES_NO_CANCEL_OPTION);
            if (result == JOptionPane.YES_OPTION) {
                saveFile();
            } else if (result == JOptionPane.CANCEL_OPTION) {
                return;
            }
        }
        textArea.setText("");
        currentFile = null;
    }

    private void openFile() {
        if (textArea.getText().length() > 0) {
            int result = JOptionPane.showConfirmDialog(this, "是否保存当前文件？", "提示", JOptionPane.YES_NO_CANCEL_OPTION);
            if (result == JOptionPane.YES_OPTION) {
                saveFile();
            } else if (result == JOptionPane.CANCEL_OPTION) {
                return;
            }
        }
        fileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
        fileChooser.setFileFilter(new FileNameExtensionFilter("文本文件(*.txt)", "txt"));
        int result = fileChooser.showOpenDialog(this);
        if (result == JFileChooser.APPROVE_OPTION) {
            File file = fileChooser.getSelectedFile();
            try (FileReader reader = new FileReader(file)) {
                char[] buffer = new char[1024];
                StringBuilder builder = new StringBuilder();
                int length;
                while ((length = reader.read(buffer)) != -1) {
                    builder.append(buffer, 0, length);
                }
                textArea.setText(builder.toString());
                currentFile = file.getAbsolutePath();
            } catch (IOException ex) {
                ex.printStackTrace();
                JOptionPane.showMessageDialog(this, "文件打开失败！", "错误", JOptionPane.ERROR_MESSAGE);
            }
        }
    }

    private void saveFile() {
        if (currentFile == null) {
            saveAsFile();
        } else {
            try (FileWriter writer = new FileWriter(currentFile)) {
                writer.write(textArea.getText());
                JOptionPane.showMessageDialog(this, "文件保存成功！", "提示", JOptionPane.INFORMATION_MESSAGE);
            } catch (IOException ex) {
                ex.printStackTrace();
                JOptionPane.showMessageDialog(this, "文件保存失败！", "错误", JOptionPane.ERROR_MESSAGE);
            }
        }
    }

    private void saveAsFile() {
        fileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
        fileChooser.setFileFilter(new FileNameExtensionFilter("文本文件(*.txt)", "txt"));
        int result = fileChooser.showSaveDialog(this);
        if (result == JFileChooser.APPROVE_OPTION) {
            File file = fileChooser.getSelectedFile();
            try (FileWriter writer = new FileWriter(file)) {
                writer.write(textArea.getText());
                currentFile = file.getAbsolutePath();
                JOptionPane.showMessageDialog(this, "文件保存成功！", "提示", JOptionPane.INFORMATION_MESSAGE);
            } catch (IOException ex) {
                ex.printStackTrace();
                JOptionPane.showMessageDialog(this, "文件保存失败！", "错误", JOptionPane.ERROR_MESSAGE);
            }
        }
    }

    private void find() {
        String text = JOptionPane.showInputDialog(this, "请输入要查找的内容：", "查找", JOptionPane.PLAIN_MESSAGE);
        if (text != null && text.length() > 0) {
            String content = textArea.getText();
            int index = content.indexOf(text);
            if (index != -1) {
                textArea.setCaretPosition(index);
                textArea.select(index, index + text.length());
            } else {
                JOptionPane.showMessageDialog(this, "未找到指定内容！", "提示", JOptionPane.INFORMATION_MESSAGE);
            }
        }
    }

    private void replace() {
        String findText = JOptionPane.showInputDialog(this, "请输入要查找的内容：", "查找", JOptionPane.PLAIN_MESSAGE);
        if (findText != null && findText.length() > 0) {
            String content = textArea.getText();
            int index = content.indexOf(findText);
            if (index != -1) {
                String replaceText = JOptionPane.showInputDialog(this, "请输入要替换的内容：", "替换", JOptionPane.PLAIN_MESSAGE);
                if (replaceText != null) {
                    content = content.substring(0, index) + replaceText + content.substring(index + findText.length());
                    textArea.setText(content);
                    textArea.setCaretPosition(index);
                    textArea.select(index, index + replaceText.length());
                }
            } else {
                JOptionPane.showMessageDialog(this, "未找到指定内容！", "提示", JOptionPane.INFORMATION_MESSAGE);
            }
        }
    }

    private void setFont() {
        Font font = textArea.getFont();
        String fontName = JOptionPane.showInputDialog(this, "请输入字体名称：", font.getName());
        if (fontName != null && fontName.length() > 0) {
            int fontStyle = font.getStyle();
            String fontStyleStr = JOptionPane.showInputDialog(this, "请输入字体样式(0:常规 1:粗体 2:斜体 3:粗斜体)：", fontStyle);
            if (fontStyleStr != null && fontStyleStr.matches("[0-3]")) {
                fontStyle = Integer.parseInt(fontStyleStr);
                int fontSize = font.getSize();
                String fontSizeStr = JOptionPane.showInputDialog(this, "请输入字体大小：", fontSize);
                if (fontSizeStr != null && fontSizeStr.matches("\\d+")) {
                    fontSize = Integer.parseInt(fontSizeStr);
                    Font newFont = new Font(fontName, fontStyle, fontSize);
                    textArea.setFont(newFont);
                }
            }
        }
    }

    public static void main(String[] args) {
        JavaNote note = new JavaNote();
        note.setVisible(true);
    }
}

这个记事本支持打开、保存和另存为文件，可以进行复制、粘贴和剪切操作，还支持查找和替换文本内容，可以设置字体。