使用DOM方式修改XML文件内容

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： 

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