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>

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>

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>

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