Java tutorial
/* * * Copyright (c) 1998 Sun Microsystems, Inc. All Rights Reserved. * * Sun grants you ("Licensee") a non-exclusive, royalty free, license to use, * modify and redistribute this software in source and binary code form, * provided that i) this copyright notice and license appear on all copies of * the software; and ii) Licensee does not utilize the software in a manner * which is disparaging to Sun. * * This software is provided "AS IS," without a warranty of any kind. ALL * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING ANY * IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR * NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE * LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING * OR DISTRIBUTING THE SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS * LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT, * INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER * CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF * OR INABILITY TO USE SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE * POSSIBILITY OF SUCH DAMAGES. * * This software is not designed or intended for use in on-line control of * aircraft, air traffic, aircraft navigation or aircraft communications; or in * the design, construction, operation or maintenance of any nuclear * facility. Licensee represents and warrants that it will not use or * redistribute the Software for such purposes. */ import java.io.*; import java.awt.*; import java.awt.event.*; import javax.swing.*; import javax.swing.filechooser.*; import javax.jnlp.*; public class JWSFileChooserDemo extends JPanel implements ActionListener { static private final String newline = "\n"; JButton openButton, saveButton; JTextArea log; public JWSFileChooserDemo() { super(new BorderLayout()); //Create the log first, because the action listeners //need to refer to it. log = new JTextArea(5, 20); log.setMargin(new Insets(5, 5, 5, 5)); log.setEditable(false); JScrollPane logScrollPane = new JScrollPane(log); //Create the open button. We use the image from the JLF //Graphics Repository (but we extracted it from the jar). openButton = new JButton("Open a File...", createImageIcon("images/Open16.gif")); openButton.addActionListener(this); //Create the save button. We use the image from the JLF //Graphics Repository (but we extracted it from the jar). saveButton = new JButton("Save a File...", createImageIcon("images/Save16.gif")); //PENDING: removed the Save button action listener //so that people won't overwrite existing files. //See bug 4761577. //saveButton.addActionListener(this); saveButton.setEnabled(false); //For layout purposes, put the buttons in a separate panel JPanel buttonPanel = new JPanel(); buttonPanel.add(openButton); buttonPanel.add(saveButton); //Add the buttons and the log to this panel. add(buttonPanel, BorderLayout.PAGE_START); add(logScrollPane, BorderLayout.CENTER); } public void actionPerformed(ActionEvent e) { //Handle open button action. if (e.getSource() == openButton) { FileOpenService fos = null; FileContents fileContents = null; try { fos = (FileOpenService) ServiceManager.lookup("javax.jnlp.FileOpenService"); } catch (UnavailableServiceException exc) { } if (fos != null) { try { fileContents = fos.openFileDialog(null, null); } catch (Exception exc) { log.append("Open command failed: " + exc.getLocalizedMessage() + newline); log.setCaretPosition(log.getDocument().getLength()); } } if (fileContents != null) { try { //This is where a real application would do something //with the file. log.append("Opened file: " + fileContents.getName() + "." + newline); } catch (IOException exc) { log.append("Problem opening file: " + exc.getLocalizedMessage() + newline); } } else { log.append("User canceled open request." + newline); } log.setCaretPosition(log.getDocument().getLength()); } //Handle save button action. if (e.getSource() == saveButton) { FileSaveService fss = null; FileContents fileContents = null; ByteArrayInputStream is = new ByteArrayInputStream( (new String("Saved by JWSFileChooserDemo").getBytes())); //XXX YIKES! If they select an //XXX existing file, this will //XXX overwrite that file. try { fss = (FileSaveService) ServiceManager.lookup("javax.jnlp.FileSaveService"); } catch (UnavailableServiceException exc) { } if (fss != null) { try { fileContents = fss.saveFileDialog(null, null, is, "JWSFileChooserDemo.txt"); } catch (Exception exc) { log.append("Save command failed: " + exc.getLocalizedMessage() + newline); log.setCaretPosition(log.getDocument().getLength()); } } if (fileContents != null) { try { log.append("Saved file: " + fileContents.getName() + "." + newline); } catch (IOException exc) { log.append("Problem saving file: " + exc.getLocalizedMessage() + newline); } } else { log.append("User canceled save request." + newline); } log.setCaretPosition(log.getDocument().getLength()); } } /** Returns an ImageIcon, or null if the path was invalid. */ protected static ImageIcon createImageIcon(String path) { java.net.URL imgURL = JWSFileChooserDemo.class.getResource(path); if (imgURL != null) { return new ImageIcon(imgURL); } else { System.err.println("Couldn't find file: " + path); return null; } } /** * Create the GUI and show it. For thread safety, * this method should be invoked from the * event-dispatching thread. */ private static void createAndShowGUI() { //Create and set up the window. JFrame frame = new JFrame("JWSFileChooserDemo"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //Create and set up the content pane. JComponent newContentPane = new JWSFileChooserDemo(); newContentPane.setOpaque(true); //content panes must be opaque frame.setContentPane(newContentPane); //Display the window. frame.pack(); frame.setVisible(true); } public static void main(String[] args) { //Schedule a job for the event-dispatching thread: //creating and showing this application's GUI. javax.swing.SwingUtilities.invokeLater(new Runnable() { public void run() { createAndShowGUI(); } }); } }