JDOM提供了非常灵活的方式操作XML文件，使用JDOM非常简单而且代码简洁可读性强。前面我们学习了如何使用JDOM解析XML文件，本节介绍如何使用JDOM修改XML文件内容。

在这个教程中，我们准备对下面的XML文件进行修改：

employees.xml

<?xml version="1.0" encoding="UTF-8"?>

<Employees xmlns="http://www.journaldev.com/employees">

  <Employee id="1">

    <age>25</age>

    <name>Pankaj</name>

    <gender>Male</gender>

    <role>Java Developer</role>

  </Employee>

  <Employee id="2">

    <age>34</age>

    <name>Mona</name>

    <gender>Female</gender>

    <role>Manager</role>

  </Employee>

  <Employee id="3">

    <age>45</age>

    <name>Dave</name>

    <gender>Male</gender>

    <role>Support</role>

  </Employee>

</Employees>

我们将改变xml中每个Employee元素：

1.修改所有name元素，使它的内容全部变成大写。

2.在gender（性别）为Male（男）的id属性值后追加M，gender（性别）为Female（女） 的id属性值后追加F。

3.删除gender元素。

4.为每个Employee元素增加salary（薪水）子元素，默认值为1000。

下面是程序代码：

JDOMXMLEditor.java

package com.journaldev.xml.jdom;

import java.io.File;

import java.io.FileOutputStream;

import java.io.IOException;

import java.util.List;

import org.jdom2.Element;

import org.jdom2.JDOMException;

import org.jdom2.Namespace;

import org.jdom2.input.SAXBuilder;

import org.jdom2.output.Format;

import org.jdom2.output.XMLOutputter;

public class JDOMXMLEditor {

    public static void main(String[] args) throws JDOMException, IOException {

        final Namespace ns = Namespace.getNamespace("http://www.journaldev.com/employees");

        //Get the JDOM document

        org.jdom2.Document doc = useSAXParser("employees.xml");

        //Get list of Employee element

        Element rootElement = doc.getRootElement();

        List<Element> listEmpElement = rootElement.getChildren("Employee", ns);

        //loop through to edit every Employee element

        for (Element empElement : listEmpElement) {

            //change the name to BLOCK letters

            String name = empElement.getChildText("name", ns);

            if (name != null)

                empElement.getChild("name", ns).setText(name.toUpperCase());

            //edit the ID attribute based on Gender

            String gender = empElement.getChildText("gender", ns);

            if (gender != null && gender.equalsIgnoreCase("female")) {

                String id = empElement.getAttributeValue("id");

                empElement.getAttribute("id").setValue(id + "F");

            } else {

                String id = empElement.getAttributeValue("id");

                empElement.getAttribute("id").setValue(id + "M");

            }

            //remove gender element as it's not needed anymore

            empElement.removeChild("gender", ns);

            //add salary element with default value to every employee

            empElement.addContent(new Element("salary", ns).setText("1000"));

        }

        //document is processed and edited successfully, lets save it in new file

        XMLOutputter xmlOutputter = new XMLOutputter(Format.getPrettyFormat());

        //output xml to console for debugging

        //xmlOutputter.output(doc, System.out);

        xmlOutputter.output(doc, new FileOutputStream("employees_new.xml"));

    }

    //Get JDOM document from SAX Parser

    private static org.jdom2.Document useSAXParser(String fileName) throws JDOMException,

            IOException {

        SAXBuilder saxBuilder = new SAXBuilder();

        return saxBuilder.build(new File(fileName));

    }

}

需要注意的是上面代码使用命名空间获取所有元素，运行程序输出XML文件内容：

employees_new.xml

<?xml version="1.0" encoding="UTF-8"?>

<Employees xmlns="http://www.journaldev.com/employees">

  <Employee id="1M">

    <age>25</age>

    <name>PANKAJ</name>

    <role>Java Developer</role>

    <salary>1000</salary>

  </Employee>

  <Employee id="2F">

    <age>34</age>

    <name>MONA</name>

    <role>Manager</role>

    <salary>1000</salary>

  </Employee>

  <Employee id="3M">

    <age>45</age>

    <name>DAVE</name>

    <role>Support</role>

    <salary>1000</salary>

  </Employee>

</Employees>