Java HTML/XML - 如何从xml文件中删除元素

import java.io.File;

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Node;

public class Main {

  public static void main(String[] args) throws Exception {
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    Document document = dbf.newDocumentBuilder().parse(new File("input.xml"));

    XPathFactory xpf = XPathFactory.newInstance();
    XPath xpath = xpf.newXPath();
    XPathExpression expression = xpath
        .compile("//data/user/username[text()='simple']");
    Node b13Node = (Node) expression.evaluate(document, XPathConstants.NODE);
    b13Node = b13Node.getParentNode();
    b13Node.getParentNode().removeChild(b13Node);

    TransformerFactory tf = TransformerFactory.newInstance();
    Transformer t = tf.newTransformer();
    t.transform(new DOMSource(document), new StreamResult(System.out));
  }
}