Java&Xml教程（七）使用JDOM修改XML文件内容

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>