Java语言怎么实现不同的字体混合在一个界面上，分门别类可以选择，可以输出的字母代码

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

public class FontMixer {
    private JFrame frame;
    private JComboBox<String> categoryComboBox;
    private JTextField codeTextField;
    private JTextPane previewTextPane;

    public FontMixer() {
        frame = new JFrame("字体混合器");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLayout(new BorderLayout());

        // 设置选择类别的下拉框
        String[] categories = {"宋体", "楷体", "Arial"};
        categoryComboBox = new JComboBox<>(categories);
        frame.add(categoryComboBox, BorderLayout.NORTH);

        // 设置输入字母代码的文本框
        codeTextField = new JTextField();
        codeTextField.setPreferredSize(new Dimension(100, 30));
        frame.add(codeTextField, BorderLayout.WEST);

        // 设置预览混合字体的文本框
        previewTextPane = new JTextPane();
        frame.add(previewTextPane, BorderLayout.CENTER);

        // 监听选择类别和输入字母代码的动作
        ActionListener actionListener = new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                String selectedCategory = (String) categoryComboBox.getSelectedItem();
                String code = codeTextField.getText();
                setMixedFont(selectedCategory, code);
            }
        };
        categoryComboBox.addActionListener(actionListener);
        codeTextField.addActionListener(actionListener);

        frame.pack();
        frame.setVisible(true);
    }

    private void setMixedFont(String category, String code) {
        Font font = new Font(category, Font.PLAIN, 24);
        MutableAttributeSet attrs = previewTextPane.getInputAttributes();
        StyleConstants.setFontFamily(attrs, font.getFamily());
        StyleConstants.setFontSize(attrs, font.getSize());
        previewTextPane.setCharacterAttributes(attrs, true);
        previewTextPane.setText(code);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new FontMixer();
            }
        });
    }
}