jwsfilechooserdemo.java

Java样例程序集合：2D

import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.filechooser.*;

import javax.jnlp.*;

/* 
 * JWSFileChooserDemo.java is a 1.4 application that must be compiled
 * with jnlp.jar.  For example, if jnlp.jar is in a subdirectory named jars:
 * 
 *   java -classpath .:jars/jnlp.jar JWSFileChooserDemo.java [UNIX]
 *   java -classpath .;jars/jnlp.jar JWSFileChooserDemo.java [Microsoft Windows]
 *
 * JWSFileChooserDemo.java requires the following files when executing:
 *   images/Open16.gif
 *   images/Save16.gif
 */
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;
            StringBufferInputStream is = new StringBufferInputStream(
                                             "Saved by JWSFileChooserDemo");
                                             //XXX deprecated class
                                             //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() {
        //Make sure we have nice window decorations.
        JFrame.setDefaultLookAndFeelDecorated(true);

        //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();
            }
        });
    }
}