之前我们学习了如何使用DOM分析器读取XML文件以及如何在Java中编辑XML文件，今天我们将学习如何使用DOM分析器用Java语言编写XML文件。

这是我们XML文件的要求。

• 根元素将是名称空间为" https：//www.theitroad.local/employee"的"雇员"。
  该根元素将包含员工列表。

• 员工信息将写在"员工"元素中。
  XML文件中将有两个员工信息。

• 每个员工都有一个名为" id"的属性

• 雇员元素将具有四个元素-"姓名"，"年龄"，"角色"，"性别"。

这是上述要求的Java程序。

package com.theitroad.xml;

import java.io.File;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

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

public class XMLWriterDOM {

  public static void main(String[] args) {
      DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
      DocumentBuilder dBuilder;
      try {
          dBuilder = dbFactory.newDocumentBuilder();
          Document doc = dBuilder.newDocument();
          //add elements to Document
          Element rootElement =
              doc.createElementNS("https://www.theitroad.local/employee", "Employees");
          //append root element to document
          doc.appendChild(rootElement);

          //append first child element to root element
          rootElement.appendChild(getEmployee(doc, "1", "hyman", "29", "Java Developer", "Male"));

          //append second child
          rootElement.appendChild(getEmployee(doc, "2", "Lisa", "35", "Manager", "Female"));

          //for output to file, console
          TransformerFactory transformerFactory = TransformerFactory.newInstance();
          Transformer transformer = transformerFactory.newTransformer();
          //for pretty print
          transformer.setOutputProperty(OutputKeys.INDENT, "yes");
          DOMSource source = new DOMSource(doc);

          //write to console or file
          StreamResult console = new StreamResult(System.out);
          StreamResult file = new StreamResult(new File("/Users/hyman/emps.xml"));

          //write data
          transformer.transform(source, console);
          transformer.transform(source, file);
          System.out.println("DONE");

      } catch (Exception e) {
          e.printStackTrace();
      }
  }

  private static Node getEmployee(Document doc, String id, String name, String age, String role,
          String gender) {
      Element employee = doc.createElement("Employee");

      //set id attribute
      employee.setAttribute("id", id);

      //create name element
      employee.appendChild(getEmployeeElements(doc, employee, "name", name));

      //create age element
      employee.appendChild(getEmployeeElements(doc, employee, "age", age));

      //create role element
      employee.appendChild(getEmployeeElements(doc, employee, "role", role));

      //create gender element
      employee.appendChild(getEmployeeElements(doc, employee, "gender", gender));

      return employee;
  }

  //utility method to create text node
  private static Node getEmployeeElements(Document doc, Element element, String name, String value) {
      Element node = doc.createElement(name);
      node.appendChild(doc.createTextNode(value));
      return node;
  }

}

请注意，我创建了两个StreamResult，一个用于在控制台中打印XML以进行调试，另一个用于将XML写入文件。

这是上述程序的输出XML。

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<Employees xmlns="https://www.theitroad.local/employee">
<Employee id="1">
<name>hyman</name>
<age>29</age>
<role>Java Developer</role>
<gender>Male</gender>
</Employee>
<Employee id="2">
<name>Lisa</name>
<age>35</age>
<role>Manager</role>
<gender>Female</gender>
</Employee>
</Employees>