Java&Xml教學（七）使用JDOM修改XML檔案內容

JDOM提供了非常靈活的方式操作XML文件，使用JDOM非常簡單且程式碼簡潔可讀性強。前面我們學習如何使用JDOM解析XML文件，本節介紹如何使用JDOM修改XML文件內容。

在這個教學中，我們準備對下面的XML檔案進行修改：
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>

我們將改變xml中每個Employee元素：
1.修改所有name元素，使它的內容全部變成大寫。
2.在gender（性別）為Male（男）的id屬性值後追加M，gender（性別）為Female（女） 的id屬性值後追加F。
3.刪除gender元素。
4.為每個Employee元素增加salary（薪水）子元素，預設值為1000。
下面是程式碼：
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&#39;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));
    }

}

需要注意的是上面程式碼使用命名空間取得所有元素，執行程式輸出XML檔案內容：
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提供了非常靈活的方式操作XML文件，使用JDOM非常簡單而且程式碼簡潔可讀性強。前面我們學習如何使用JDOM解析XML文件，本節介紹如何使用JDOM修改XML文件內容。
在這個教學中，我們準備對下面的XML檔案進行修改：
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>

我們將改變xml中每個Employee元素：
1.修改所有name元素，使它的內容全部變成大寫。
2.在gender（性別）為Male（男）的id屬性值後追加M，gender（性別）為Female（女） 的id屬性值後追加F。
3.刪除gender元素。
4.為每個Employee元素增加salary（薪水）子元素，預設值為1000。
下面是程式碼：
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&#39;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));
    }

}

需要注意的是上面程式碼使用命名空間取得所有元素，執行程式輸出XML檔案內容：
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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