JTextPane动态缩进！情况

import javax.swing.*;
import javax.swing.text.*;

public class JTextPaneDemo {
    public static void main(String[] args) {
        JFrame frame = new JFrame("JTextPane Demo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JTextPane textPane = new JTextPane();
        textPane.setEditable(false);

        StyledDocument doc = textPane.getStyledDocument();
        SimpleAttributeSet paraAttr = new SimpleAttributeSet();
        StyleConstants.setLeftIndent(paraAttr, 20); // 设置缩进为20像素

        try {
            doc.insertString(doc.getLength(), "第一级文本\n", null);
            doc.insertString(doc.getLength(), "第二级文本\n", paraAttr);
            doc.insertString(doc.getLength(), "第三级文本\n", paraAttr);
        } catch (BadLocationException e) {
            e.printStackTrace();
        }

        JScrollPane scrollPane = new JScrollPane(textPane);
        frame.getContentPane().add(scrollPane);

        frame.setSize(400, 300);
        frame.setVisible(true);
    }
}