Java HTML/XML - 如何递归访问DOM xml孩子

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.OutputStreamWriter;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

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

public class Main {
  public static void main(String[] args) throws Exception {
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    dbf.setValidating(false);
    DocumentBuilder db = dbf.newDocumentBuilder();
    Document doc = db.parse(new FileInputStream(new File("input.xml")));
    File OutputDOM = new File("out.txt");
    FileOutputStream fostream = new FileOutputStream(OutputDOM);
    OutputStreamWriter oswriter = new OutputStreamWriter(fostream);
    BufferedWriter bwriter = new BufferedWriter(oswriter);
    if (!OutputDOM.exists()) {
      OutputDOM.createNewFile();
    }
    visitRecursively(doc, bwriter);
    bwriter.close();
    oswriter.close();
    fostream.close();
  }
  public static void visitRecursively(Node node, BufferedWriter bw)
      throws Exception {
    NodeList list = node.getChildNodes();
    for (int i = 0; i < list.getLength(); i++) {
      // get child node
      Node childNode = list.item(i);
      if (childNode.getNodeType() == Node.TEXT_NODE) {
         System.out.println("Found Node: " + childNode.getNodeName()
         + " - with value: " +
         childNode.getNodeValue()+" Node type:"+childNode.getNodeType());

        String nodeValue = childNode.getNodeValue();
        nodeValue = nodeValue.replace("\n", "").replaceAll("\\s", "");
        if (!nodeValue.isEmpty()) {
          System.out.println(nodeValue);
          bw.write(nodeValue);
          bw.newLine();
        }
      }
      visitRecursively(childNode, bw);
    }
  }
}