Command Pattern - Example: FTP GUI
/*
Software Architecture Design Patterns in Java
by Partha Kuchana
Auerbach Publications
*/
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.DefaultListModel;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.ListSelectionModel;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import com.sun.java.swing.plaf.windows.WindowsLookAndFeel;
public class FTPGUI extends JFrame {
public static final String newline = "\n";
public static final String UPLOAD = "Upload";
public static final String DOWNLOAD = "Download";
public static final String DELETE = "Delete";
public static final String EXIT = "Exit";
private JPanel pnlFTPUI;
private JList localList;
private JList remoteList;
private DefaultListModel defLocalList, defRemoteList;
private UploadButton btnUpload;
private DownloadButton btnDownload;
private DeleteButton btnDelete;
public FTPGUI() throws Exception {
super("Command Pattern - Example");
// Create controls
defLocalList = new DefaultListModel();
defRemoteList = new DefaultListModel();
localList = new JList(defLocalList);
remoteList = new JList(defRemoteList);
pnlFTPUI = new JPanel();
localList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
localList.setSelectedIndex(-1);
JScrollPane spLocalList = new JScrollPane(localList);
remoteList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
remoteList.setSelectedIndex(-1);
JScrollPane spRemoteList = new JScrollPane(remoteList);
//Create Labels
JLabel lblLocalList = new JLabel("Local List:");
JLabel lblRemoteList = new JLabel("Remote List:");
JLabel lblSpacer = new JLabel(" ");
//Create buttons
btnUpload = new UploadButton(FTPGUI.UPLOAD);
btnUpload.setMnemonic(KeyEvent.VK_U);
btnDownload = new DownloadButton(FTPGUI.DOWNLOAD);
btnDownload.setMnemonic(KeyEvent.VK_N);
btnDelete = new DeleteButton(FTPGUI.DELETE);
btnDelete.setMnemonic(KeyEvent.VK_D);
ExitButton btnExit = new ExitButton(FTPGUI.EXIT);
btnExit.setMnemonic(KeyEvent.VK_X);
buttonHandler vf = new buttonHandler();
btnUpload.addActionListener(vf);
btnDownload.addActionListener(vf);
btnDelete.addActionListener(vf);
btnExit.addActionListener(vf);
JPanel lstPanel = new JPanel();
GridBagLayout gridbag2 = new GridBagLayout();
lstPanel.setLayout(gridbag2);
GridBagConstraints gbc2 = new GridBagConstraints();
lstPanel.add(lblLocalList);
lstPanel.add(lblRemoteList);
lstPanel.add(spLocalList);
lstPanel.add(spRemoteList);
lstPanel.add(lblSpacer);
gbc2.gridx = 0;
gbc2.gridy = 0;
gridbag2.setConstraints(lblLocalList, gbc2);
gbc2.gridx = 1;
gbc2.gridy = 0;
gridbag2.setConstraints(lblSpacer, gbc2);
gbc2.gridx = 5;
gbc2.gridy = 0;
gridbag2.setConstraints(lblRemoteList, gbc2);
gbc2.gridx = 0;
gbc2.gridy = 1;
gridbag2.setConstraints(spLocalList, gbc2);
gbc2.gridx = 5;
gbc2.gridy = 1;
gridbag2.setConstraints(spRemoteList, gbc2);
//-----------------------------------
//For layout purposes, put the buttons in a separate panel
JPanel buttonPanel = new JPanel();
//----------------------------------------------
GridBagLayout gridbag = new GridBagLayout();
buttonPanel.setLayout(gridbag);
GridBagConstraints gbc = new GridBagConstraints();
buttonPanel.add(lstPanel);
buttonPanel.add(btnUpload);
buttonPanel.add(btnDownload);
buttonPanel.add(btnDelete);
buttonPanel.add(btnExit);
gbc.insets.top = 5;
gbc.insets.bottom = 5;
gbc.insets.left = 5;
gbc.insets.right = 5;
gbc.anchor = GridBagConstraints.WEST;
gbc.gridx = 1;
gbc.gridy = 0;
gridbag.setConstraints(btnUpload, gbc);
gbc.gridx = 2;
gbc.gridy = 0;
gridbag.setConstraints(btnDownload, gbc);
gbc.gridx = 3;
gbc.gridy = 0;
gridbag.setConstraints(btnDelete, gbc);
gbc.gridx = 4;
gbc.gridy = 0;
gridbag.setConstraints(btnExit, gbc);
gbc.gridx = 0;
gbc.gridy = 1;
gridbag.setConstraints(lstPanel, gbc);
gbc.anchor = GridBagConstraints.EAST;
gbc.insets.left = 2;
gbc.insets.right = 2;
gbc.insets.top = 40;
//****************************************************
//Add the buttons and the log to the frame
Container contentPane = getContentPane();
contentPane.add(lstPanel, BorderLayout.CENTER);
contentPane.add(buttonPanel, BorderLayout.SOUTH);
initialize();
try {
UIManager.setLookAndFeel(new WindowsLookAndFeel());
SwingUtilities.updateComponentTreeUI(FTPGUI.this);
} catch (Exception ex) {
System.out.println(ex);
}
}
private void initialize() {
// fill some test data here into the listbox.
defLocalList.addElement("first.html");
defLocalList.addElement("second.html");
defLocalList.addElement("third.html");
defLocalList.addElement("fourth.html");
defLocalList.addElement("fifth.html");
defLocalList.addElement("Design Patterns 1.html");
defRemoteList.addElement("sixth.html");
defRemoteList.addElement("seventh.html");
defRemoteList.addElement("eighth.html");
defRemoteList.addElement("ninth.html");
defRemoteList.addElement("Design Patterns 2.html");
}
public static void main(String[] args) throws Exception {
JFrame frame = new FTPGUI();
frame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
//frame.pack();
frame.setSize(450, 300);
frame.setVisible(true);
}
class buttonHandler implements ActionListener {
public void actionPerformed(ActionEvent e) {
CommandInterface CommandObj = (CommandInterface) e.getSource();
CommandObj.processEvent();
}
}
interface CommandInterface {
public void processEvent();
}
class UploadButton extends JButton implements CommandInterface {
public void processEvent() {
int index = localList.getSelectedIndex();
String selectedItem = localList.getSelectedValue().toString();
((DefaultListModel) localList.getModel()).remove(index);
((DefaultListModel) remoteList.getModel()).addElement(selectedItem);
}
public UploadButton(String name) {
super(name);
}
}
class DownloadButton extends JButton implements CommandInterface {
public void processEvent() {
int index = remoteList.getSelectedIndex();
String selectedItem = remoteList.getSelectedValue().toString();
((DefaultListModel) remoteList.getModel()).remove(index);
((DefaultListModel) localList.getModel()).addElement(selectedItem);
}
public DownloadButton(String name) {
super(name);
}
}
class DeleteButton extends JButton implements CommandInterface {
public void processEvent() {
int index = localList.getSelectedIndex();
if (index >= 0) {
((DefaultListModel) localList.getModel()).remove(index);
}
index = remoteList.getSelectedIndex();
if (index >= 0) {
((DefaultListModel) remoteList.getModel()).remove(index);
}
}
public DeleteButton(String name) {
super(name);
}
}
class ExitButton extends JButton implements CommandInterface {
public void processEvent() {
System.exit(1);
}
public ExitButton(String name) {
super(name);
}
}
}// end of class
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