如何在使用java的DOM解析器之后对XML元素进行排序

import org.w3c.dom.*;
import javax.xml.parsers.*;
import java.io.*;
import java.util.*;

public class XMLSorter {
    public static void main(String[] args) {
        try {
            // 创建DOM解析器工厂
            DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
            // 创建DOM解析器
            DocumentBuilder builder = factory.newDocumentBuilder();
            // 解析XML文件，获取DOM树
            Document doc = builder.parse(new File("input.xml"));

            // 获取需要排序的XML元素
            NodeList nodeList = doc.getElementsByTagName("element");

            // 将XML元素存储到List中
            List<Element> elements = new ArrayList<>();
            for (int i = 0; i < nodeList.getLength(); i++) {
                Element element = (Element) nodeList.item(i);
                elements.add(element);
            }

            // 自定义Comparator，按照元素的某个属性进行排序
            Collections.sort(elements, new Comparator<Element>() {
                @Override
                public int compare(Element e1, Element e2) {
                    String attr1 = e1.getAttribute("attribute");
                    String attr2 = e2.getAttribute("attribute");
                    return attr1.compareTo(attr2);
                }
            });

            // 创建一个新的DOM树
            Document newDoc = builder.newDocument();
            Element root = newDoc.createElement("root");
            newDoc.appendChild(root);

            // 将排序后的XML元素插入到新的DOM树中
            for (Element element : elements) {
                Element newElement = newDoc.createElement("element");
                newElement.setAttribute("attribute", element.getAttribute("attribute"));
                newElement.setTextContent(element.getTextContent());
                root.appendChild(newElement);
            }

            // 将新的DOM树写回到XML文件中
            TransformerFactory transformerFactory = TransformerFactory.newInstance();
            Transformer transformer = transformerFactory.newTransformer();
            transformer.setOutputProperty(OutputKeys.INDENT, "yes");
            transformer.transform(new DOMSource(newDoc), new StreamResult(new File("output.xml")));

            System.out.println("XML元素排序完成！");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}