如何复制一个元素(文本字符串)的内容并附加到另一个元素的内容中？(XML)

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;

public class XMLCopyExample {
    public static void main(String[] args) {
        try {
            // 加载XML文档
            DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
            DocumentBuilder builder = factory.newDocumentBuilder();
            Document document = builder.parse("input.xml");

            // 找到源元素和目标元素
            Element sourceElement = (Element) document.getElementsByTagName("source").item(0);
            Element targetElement = (Element) document.getElementsByTagName("target").item(0);

            // 复制源元素的内容并附加到目标元素的内容中
            String sourceContent = sourceElement.getTextContent();
            String targetContent = targetElement.getTextContent();
            targetElement.setTextContent(targetContent + sourceContent);

            // 输出修改后的XML文档
            TransformerFactory transformerFactory = TransformerFactory.newInstance();
            Transformer transformer = transformerFactory.newTransformer();
            DOMSource source = new DOMSource(document);
            StreamResult result = new StreamResult(System.out);
            transformer.transform(source, result);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}