DOMParser

package it.cefi.view;
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.io.File;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.xml.parsers.*;
import javax.xml.transform.TransformerException;
import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

@SuppressWarnings("serial")
public class DOMParser extends JFrame {

    public static final String xmlFilePath = "C:\\Users\\utente\\Desktop\\peoples.xml";

    public DOMParser() {

        JFrame mainFrame = new JFrame("DOMParser");
        mainFrame.setLayout(new BoxLayout(mainFrame.getContentPane(), BoxLayout.PAGE_AXIS));
        JPanel upperPanel = new JPanel();
        upperPanel.setLayout(new GridLayout(0, 2,5,5));

        JPanel lowerPanel = new JPanel();
        lowerPanel.setLayout(new BoxLayout(lowerPanel, BoxLayout.LINE_AXIS));

        JLabel personIdLabel = new JLabel("PersonID");
        JLabel firstNameLabel = new JLabel("FirstName");
        JLabel lastNameLabel = new JLabel("LastName");
        JTextField personIdText = new JTextField();
        JTextField firstNameText = new JTextField();
        JTextField lastNameText = new JTextField();
        JButton xmlButton = new JButton("Create XML");

        upperPanel.add(personIdLabel);
        upperPanel.add(personIdText);
        upperPanel.add(firstNameLabel);
        upperPanel.add(firstNameText);
        upperPanel.add(lastNameLabel);
        upperPanel.add(lastNameText);
        lowerPanel.add(xmlButton, BorderLayout.WEST);

        mainFrame.add(upperPanel);
        mainFrame.add(lowerPanel);
        mainFrame.setSize(400, 225);
        mainFrame.setLocationRelativeTo(null);
        mainFrame.setVisible(true);
        xmlButton.addActionListener(e -> {

            try {

                DocumentBuilderFactory documentFactory = DocumentBuilderFactory.newInstance();
                DocumentBuilder documentBuilder = documentFactory.newDocumentBuilder();
                Document document = documentBuilder.newDocument();

                Element root = document.createElement("people");
                document.appendChild(root);

                Element personId = document.createElement("person");
                root.appendChild(personId);

                Attr attr = document.createAttribute("id");
                attr.setValue(personIdText.getText().toString());
                personId.setAttributeNode(attr);

                Element firstName = document.createElement("firstname");
                firstName.appendChild(document.createTextNode(firstNameText.getText().toString()));
                personId.appendChild(firstName);

                Element lastname = document.createElement("lastname");
                lastname.appendChild(document.createTextNode(lastNameText.getText().toString()));
                personId.appendChild(lastname);

                //Transformer e Factory sono due design partner
                TransformerFactory transformerFactory = TransformerFactory.newInstance();
                Transformer transformer = transformerFactory.newTransformer();

                DOMSource domSource = new DOMSource(document);
                StreamResult streamResult = new StreamResult(new File(xmlFilePath));
                transformer.transform(domSource, streamResult);

                firstNameText.setText(null);
                personIdText.setText(null);
                lastNameText.setText(null);

            } catch (ParserConfigurationException |  TransformerException pce) {
                pce.printStackTrace();
            }

        });
    }
}