Criando um menu dinâmico usando XML

A princípio este artigo dará uma idéia de como montar um menu usando uma estrutura de XML, é claro que existem outros métodos que não foram aqui abordados. Nos códigos apresentados abaixo eu usei um pouco do conceito de Reflexão.

Segue abaixo o código fonte de uma implementação simples, onde o XML contém os parâmetros e a estrutura do menu.

Este primeiro código irá buscar cada nodo da estrutura do XML.

//---- xmlJmenuBar.java

package Xml;

import Principal.OuvinteItemMenu;

import java.awt.Container;

import java.awt.event.ActionEvent;

import java.util.ArrayList;

import java.util.List;

import javax.swing.JCheckBoxMenuItem;

import javax.swing.JMenu;

import javax.swing.JMenuBar;

import javax.swing.JMenuItem;

import javax.swing.JRadioButtonMenuItem;

import org.w3c.dom.Attr;

import org.w3c.dom.Document;

import org.w3c.dom.Element;

import org.w3c.dom.Node;

import org.w3c.dom.NodeList;

/**

 *

 * @author Chrystian  Toigo

 */

public class xmlJmenuBar extends JMenuBar {

private Container   content;

/** Creates a new instance of xmlJmenuBar */

public xmlJmenuBar(Document document) {

this.add(menuBarAusDocument(document));

}

public void actionPerformed(ActionEvent event) {

String cmd = event.getActionCommand();

if (cmd.equals("ende"))

System.exit(0);

}

static public List getChildElements(Element element, String name) {

List list = new ArrayList();

if (element.hasChildNodes())

for (Node node = element.getFirstChild(); node != null; node = node.getNextSibling())

if (node.getNodeName().equals(name))

list.add(node);

return list;

}

private JMenuItem itemAusElement(Element element) {

String tagname = element.getNodeName();

if (tagname.equals("menuBar")) {

return menuAusElement(element);

}

if (tagname.equals("menuItem")) {

JMenuItem   item;

Stringname= getAttributeValue(element, "name"),

command = getAttributeValue(element, "command"),

type= getAttributeValue(element, "type"),

classe  = getAttributeValue(element, "classe");

if ("check".equals(type))// Checkbox

item = new JCheckBoxMenuItem(name);

else if ("radio".equals(type))

item = new JRadioButtonMenuItem(name);  // Radio

else

item = new JMenuItem(name);// normal

if (classe.length() == 0) {

OuvinteItemMenu ouvinte = new OuvinteItemMenu(classe);

item.addActionListener(ouvinte);

}

if (command != null)

item.setActionCommand(command);// actionCommand setzen

return item;

}

return null;

}

JMenuBar menuBarAusDocument(Document document) {

JMenuBarmenuBar = new JMenuBar();

ListmenuList = getChildElements(document.getDocumentElement(),"menuBar");

intnMenus = menuList.size();

for (int i = 0; i < nMenus; ++i) {

JMenu menu = menuAusElement((Element)menuList.get(i));

menuBar.add(menu);

}

return menuBar;

}

private JMenu menuAusElement(Element element) {

NodeListitems  = element.getChildNodes();

intnItems = items.getLength();

JMenumenu   = new JMenu(getAttributeValue(element, "name"));

for (int i = 0; i < nItems; ++i) {

Nodenode = items.item(i);

if (node.getNodeType() == Node.ELEMENT_NODE)

menu.add(itemAusElement((Element)node));

}

return menu;

}

static public String getAttributeValue(Element element, String name) {

Attr attr = element.getAttributeNode(name);

return attr != null ? attr.getValue() : null;

}

}

Listagem 01. xmlJmenuBar.java

Estrutura do arquivo XML como irá ficar para que o programa funcione corretamente.

//-- implementacao do AccipiensMenu.xml -------------------------------------

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

<AccipiensMenu>

<menuBar name="Manutencao">

<menuBar name="Cadastro">

<menuItem name="Cliente" classe="Principal.CadastroClientes"></menuItem>

</menuBar>

<menuItem name="Relatorios"></menuItem>

<menuItem name="Consultas"></menuItem>

<menuItem name="Miscelania"></menuItem>

</menuBar>

<menuBar name="Miscelania">

<menuItem name="Teste"></menuItem>

<menuItem name="Aqui"></menuItem>

  <menuItem name="Consegui"></menuItem>

</menuBar>

</AccipiensMenu>

Listagem 02. AccipiensMenu.xml

Programa principal que irá chamar a classe que montará a estrutura do menu.

//----- jmenuWindow.java

package Principal;

import Utilities.jmenuBar;

import Xml.xmlJmenuBar;

import java.awt.BorderLayout;

import java.awt.Dimension;

import java.awt.Toolkit;

import java.awt.event.ActionEvent;  

import java.awt.event.ActionListener;  

import java.io.IOException;

import javax.swing.JDialog;

import javax.swing.JFrame;  

import javax.swing.JPanel;

import javax.swing.UIManager;

import javax.xml.parsers.DocumentBuilder;

import javax.xml.parsers.DocumentBuilderFactory;

import javax.xml.parsers.ParserConfigurationException;

import org.w3c.dom.Document;

import org.xml.sax.SAXException;

/**

 *

 * @author Chrystian  Toigo

 */

public class jmenuWindow extends JFrame {

private Dimension dimension  = Toolkit.getDefaultToolkit().getScreenSize();  

/** Creates a new instance of jmenuWindow */

public jmenuWindow() {

initComponents();

}

private void initComponents() {

DocumentBuilderFactory  factory = DocumentBuilderFactory.newInstance();

DocumentBuilderbuilder;

Document document;

dimension.height -= 30;

setSize(dimension.width, dimension.height);

setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

getContentPane().setLayout(new BorderLayout());

try {

builder = factory.newDocumentBuilder();

document = builder.parse("C:/AccipiensMenu.xml");// 1. Parameter ist Dateiname

getContentPane().add(new xmlJmenuBar(document),  BorderLayout.NORTH);

} catch (ParserConfigurationException ex) {

ex.printStackTrace();

} catch (SAXException ex) {

ex.printStackTrace();

} catch (IOException ex) {

ex.printStackTrace();

}

   }

public static void main(String[] args) {

JDialog.setDefaultLookAndFeelDecorated(false);

JFrame.setDefaultLookAndFeelDecorated(true);

Toolkit.getDefaultToolkit().setDynamicLayout(true);

System.setProperty("sun.awt.noerasebackground","true");

UIManager.put("OptionPane.yesButtonText", "Sim");

UIManager.put("OptionPane.noButtonText", "Não");

UIManager.put("OptionPane.cancelButtonText", "Cancelar");

UIManager.put("FileChooser.titleText", "Abrir");

UIManager.put("FileChooser.cancelButtonText", "Cancelar");

UIManager.put("FileChooser.cancelButtonToolTipText", "Cancelar a escolha do arquivo");

UIManager.put("FileChooser.saveButtonText", "Salvar");

UIManager.put("FileChooser.saveButtonToolTipText", "Salvar o arquivo selecionado");

UIManager.put("FileChooser.openButtonText", "Abrir");

UIManager.put("FileChooser.openButtonToolTipText", "Abrir o arquivo selecionado");

try {

UIManager.setLookAndFeel(UIManager.getCrossPlatformLookAndFeelClassName());

} catch (Exception exc) {

System.err.println("Error loading L&F: " + exc);

}

new jmenuWindow().setVisible(true);

}  

}

Listagem 03. jmenuWindow.java

Crie uma classe que será o ouvinte dos eventos não como uma classe interna anônima, mas uma classe separada. Dessa forma, para cada item de menu que for criada, irá criar um novo objeto para ouvir o evento.

//-----OuvinteItemMenu.java

package Principal;

import java.awt.event.ActionEvent;  

import java.awt.event.ActionListener;  

import javax.swing.JFrame;  

/**

 *

 * @author Chrystian  Toigo

 */

public class OuvinteItemMenu implements ActionListener {

private String className = null;

/** Creates a new instance of OuvinteItemMenu */

public OuvinteItemMenu(String className) {  

this.className = className;  

}

public void actionPerformed(ActionEvent e) {  

Class classe = null;  

try {  

classe = Class.forName(this.className);  

JFrame frame = (JFrame) classe.newInstance();  

frame.setVisible(true);  

} catch (Exception ex) {  

ex.printStackTrace();  

}  

}  

}

Listagem 04. OuvinteItemMenu.java

Enfim a classe de cadastro de clientes.

//-----CadastroClientes.java

package Principal;

import javax.swing.JLabel;

/**

 *

 * @author  Chrystian  Toigo

 */

public class CadastroClientes extends javax.swing.JFrame {

/** Creates new form CadastroClientes */

public CadastroClientes() {

initComponents();

}

/** This method is called from within the constructor to

* initialize the form.

* WARNING: Do NOT modify this code. The content of this method is

* always regenerated by the Form Editor.

*/

// <editor-fold defaultstate="collapsed" desc=" Generated Code ">//GEN-BEGIN:initComponents

private void initComponents() {

jTextField1 = new javax.swing.JTextField();

setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

jTextField1.setText("jTextField1");

org.jdesktop.layout.GroupLayout layout = new org.jdesktop.layout.GroupLayout(getContentPane());

getContentPane().setLayout(layout);

layout.setHorizontalGroup(

layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)

.add(layout.createSequentialGroup()

.add(66, 66, 66)

.add(jTextField1, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, 396, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)

.addContainerGap(108, Short.MAX_VALUE))

);

layout.setVerticalGroup(

layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)

.add(layout.createSequentialGroup()

.add(30, 30, 30)

.add(jTextField1, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)

.addContainerGap(264, Short.MAX_VALUE))

);

pack();

}// </editor-fold>//GEN-END:initComponents

/**

* @param args the command line arguments

*/

public static void main(String args[]) {

java.awt.EventQueue.invokeLater(new Runnable() {

public void run() {

new CadastroClientes().setVisible(true);

}

});

    }

// Variables declaration - do not modify//GEN-BEGIN:variables

private javax.swing.JTextField jTextField1;

// End of variables declaration//GEN-END:variables

}

Listagem 05. CadastroClientes.java