DOM解析方式也可用于修改XML数据，我们可以使用它完成新增元素、删除元素、修改元素值、修改元素属性等操作。

我们的XML文件，内容如下：

employee.xml

<?xml version="1.0" encoding="UTF-8" standalone="no"?>

<Employees>

    <Employee id="1">

        <name>Pankaj</name>

        <age>29</age>

        <role>Java Developer</role>

        <gender>Male</gender>

    </Employee>

    <Employee id="2">

        <name>Lisa</name>

        <age>35</age>

        <role>CSS Developer</role>

        <gender>Female</gender>

    </Employee>

</Employees>

我们将修改XML文件的内容：

1.根据员工的性别（gender）修改”id”属性值，性别为男（Male)的id属性值中追加”M”，为女（Female)的id属性值追加”F”。

2.修改name元素的值，全部变成大写。

3.”gender”元素已经没有存在的意义了，我们删除它。

4.在employee节点下新增一个”salary”节点。

当我们完成上述操作后，将内容保存在一个新的xml文件中。

下面是使用DOM方式解析的Java程序代码：

ModifyXMLDOM.java

package com.journaldev.xml;

import java.io.File;

import java.io.IOException;

import javax.xml.parsers.DocumentBuilder;

import javax.xml.parsers.DocumentBuilderFactory;

import javax.xml.parsers.ParserConfigurationException;

import javax.xml.transform.OutputKeys;

import javax.xml.transform.Transformer;

import javax.xml.transform.TransformerException;

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;

import org.w3c.dom.NodeList;

import org.xml.sax.SAXException;

public class ModifyXMLDOM {

    public static void main(String[] args) {

        String filePath = "employee.xml";

        File xmlFile = new File(filePath);

        DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();

        DocumentBuilder dBuilder;

        try {

            dBuilder = dbFactory.newDocumentBuilder();

            Document doc = dBuilder.parse(xmlFile);

            doc.getDocumentElement().normalize();

            //update attribute value

            updateAttributeValue(doc);

            //update Element value

            updateElementValue(doc);

            //delete element

            deleteElement(doc);

            //add new element

            addElement(doc);

            //write the updated document to file or console

            doc.getDocumentElement().normalize();

            TransformerFactory transformerFactory = TransformerFactory.newInstance();

            Transformer transformer = transformerFactory.newTransformer();

            DOMSource source = new DOMSource(doc);

            StreamResult result = new StreamResult(new File("employee_updated.xml"));

            transformer.setOutputProperty(OutputKeys.INDENT, "yes");

            transformer.transform(source, result);

            System.out.println("XML file updated successfully");

        } catch (SAXException | ParserConfigurationException | IOException | TransformerException e1) {

            e1.printStackTrace();

        }

    }

    private static void addElement(Document doc) {

        NodeList employees = doc.getElementsByTagName("Employee");

        Element emp = null;

        //loop for each employee

        for(int i=0; i<employees.getLength();i++){

            emp = (Element) employees.item(i);

            Element salaryElement = doc.createElement("salary");

            salaryElement.appendChild(doc.createTextNode("10000"));

            emp.appendChild(salaryElement);

        }

    }

    private static void deleteElement(Document doc) {

        NodeList employees = doc.getElementsByTagName("Employee");

        Element emp = null;

        //loop for each employee

        for(int i=0; i<employees.getLength();i++){

            emp = (Element) employees.item(i);

            Node genderNode = emp.getElementsByTagName("gender").item(0);

            emp.removeChild(genderNode);

        }

    }

    private static void updateElementValue(Document doc) {

        NodeList employees = doc.getElementsByTagName("Employee");

        Element emp = null;

        //loop for each employee

        for(int i=0; i<employees.getLength();i++){

            emp = (Element) employees.item(i);

            Node name = emp.getElementsByTagName("name").item(0).getFirstChild();

            name.setNodeValue(name.getNodeValue().toUpperCase());

        }

    }

    private static void updateAttributeValue(Document doc) {

        NodeList employees = doc.getElementsByTagName("Employee");

        Element emp = null;

        //loop for each employee

        for(int i=0; i<employees.getLength();i++){

            emp = (Element) employees.item(i);

            String gender = emp.getElementsByTagName("gender").item(0).getFirstChild().getNodeValue();

            if(gender.equalsIgnoreCase("male")){

                //prefix id attribute with M

                emp.setAttribute("id", "M"+emp.getAttribute("id"));

            }else{

                //prefix id attribute with F

                emp.setAttribute("id", "F"+emp.getAttribute("id"));

            }

        }

    }

}

输出xml文件内容：

employee_updated.xml

<?xml version="1.0" encoding="UTF-8" standalone="no"?>

<Employees>

    <Employee id="M1">

        <name>PANKAJ</name>

        <age>29</age>

        <role>Java Developer</role>

    <salary>10000</salary>

</Employee>

    <Employee id="F2">

        <name>LISA</name>

        <age>35</age>

        <role>CSS Developer</role>

    <salary>10000</salary>

</Employee>

</Employees>

原文地址：http://www.journaldev.com/901/how-to-edit-xml-file-in-java-dom-parser