Create Custom file chooser with image preview panel - Java Swing

Description

Create Custom file chooser with image preview panel

Demo Code

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.io.File;

import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.filechooser.FileFilter;
import javax.swing.filechooser.FileView;

/* ImagePreview.java by FileChooserDemo2.java. */
class ImagePreview extends JComponent implements PropertyChangeListener {
  ImageIcon thumbnail = null;/* ww w . jav  a  2 s  .com*/
  File file = null;

  public ImagePreview(JFileChooser fc) {
    setPreferredSize(new Dimension(100, 50));
    fc.addPropertyChangeListener(this);
  }

  public void loadImage() {
    if (file == null) {
      thumbnail = null;
      return;
    }

    // Don't use createImageIcon (which is a wrapper for getResource)
    // because the image we're trying to load is probably not one
    // of this program's own resources.
    ImageIcon tmpIcon = new ImageIcon(file.getPath());
    if (tmpIcon != null) {
      if (tmpIcon.getIconWidth() > 90) {
        thumbnail = new ImageIcon(tmpIcon.getImage().getScaledInstance(90, -1,
            Image.SCALE_DEFAULT));
      } else { // no need to miniaturize
        thumbnail = tmpIcon;
      }
    }
  }

  public void propertyChange(PropertyChangeEvent e) {
    boolean update = false;
    String prop = e.getPropertyName();

    // If the directory changed, don't show an image.
    if (JFileChooser.DIRECTORY_CHANGED_PROPERTY.equals(prop)) {
      file = null;
      update = true;

      // If a file became selected, find out which one.
    } else if (JFileChooser.SELECTED_FILE_CHANGED_PROPERTY.equals(prop)) {
      file = (File) e.getNewValue();
      update = true;
    }

    // Update the preview accordingly.
    if (update) {
      thumbnail = null;
      if (isShowing()) {
        loadImage();
        repaint();
      }
    }
  }

  protected void paintComponent(Graphics g) {
    if (thumbnail == null) {
      loadImage();
    }
    if (thumbnail != null) {
      int x = getWidth() / 2 - thumbnail.getIconWidth() / 2;
      int y = getHeight() / 2 - thumbnail.getIconHeight() / 2;

      if (y < 0) {
        y = 0;
      }

      if (x < 5) {
        x = 5;
      }
      thumbnail.paintIcon(this, g, x, y);
    }
  }
}

/* Utils.java is used by FileChooserDemo2.java. */
class Utils {
  public final static String jpeg = "jpeg";
  public final static String jpg = "jpg";
  public final static String gif = "gif";
  public final static String tiff = "tiff";
  public final static String tif = "tif";
  public final static String png = "png";

  /*
   * Get the extension of a file.
   */
  public static String getExtension(File f) {
    String ext = null;
    String s = f.getName();
    int i = s.lastIndexOf('.');

    if (i > 0 && i < s.length() - 1) {
      ext = s.substring(i + 1).toLowerCase();
    }
    return ext;
  }

  /** Returns an ImageIcon, or null if the path was invalid. */
  protected static ImageIcon createImageIcon(String path) {
    java.net.URL imgURL = Utils.class.getResource(path);
    if (imgURL != null) {
      return new ImageIcon(imgURL);
    } else {
      System.err.println("Couldn't find file: " + path);
      return null;
    }
  }
}

/* ImageFilter.java is used by FileChooserDemo2.java. */
class ImageFilter extends FileFilter {

  // Accept all directories and all gif, jpg, tiff, or png files.
  public boolean accept(File f) {
    if (f.isDirectory()) {
      return true;
    }

    String extension = Utils.getExtension(f);
    if (extension != null) {
      if (extension.equals(Utils.tiff) || extension.equals(Utils.tif)
          || extension.equals(Utils.gif) || extension.equals(Utils.jpeg)
          || extension.equals(Utils.jpg) || extension.equals(Utils.png)) {
        return true;
      } else {
        return false;
      }
    }

    return false;
  }

  // The description of this filter
  public String getDescription() {
    return "Just Images";
  }
}

/* ImageFileView.java is used by FileChooserDemo2.java. */
class ImageFileView extends FileView {
  ImageIcon jpgIcon = Utils.createImageIcon("images/jpgIcon.gif");
  ImageIcon gifIcon = Utils.createImageIcon("images/gifIcon.gif");
  ImageIcon tiffIcon = Utils.createImageIcon("images/tiffIcon.gif");
  ImageIcon pngIcon = Utils.createImageIcon("images/pngIcon.png");

  public String getName(File f) {
    return null; // let the L&F FileView figure this out
  }

  public String getDescription(File f) {
    return null; // let the L&F FileView figure this out
  }

  public Boolean isTraversable(File f) {
    return null; // let the L&F FileView figure this out
  }

  public String getTypeDescription(File f) {
    String extension = Utils.getExtension(f);
    String type = null;

    if (extension != null) {
      if (extension.equals(Utils.jpeg) || extension.equals(Utils.jpg)) {
        type = "JPEG Image";
      } else if (extension.equals(Utils.gif)) {
        type = "GIF Image";
      } else if (extension.equals(Utils.tiff) || extension.equals(Utils.tif)) {
        type = "TIFF Image";
      } else if (extension.equals(Utils.png)) {
        type = "PNG Image";
      }
    }
    return type;
  }

  public Icon getIcon(File f) {
    String extension = Utils.getExtension(f);
    Icon icon = null;

    if (extension != null) {
      if (extension.equals(Utils.jpeg) || extension.equals(Utils.jpg)) {
        icon = jpgIcon;
      } else if (extension.equals(Utils.gif)) {
        icon = gifIcon;
      } else if (extension.equals(Utils.tiff) || extension.equals(Utils.tif)) {
        icon = tiffIcon;
      } else if (extension.equals(Utils.png)) {
        icon = pngIcon;
      }
    }
    return icon;
  }
}

/*
 * FileChooserDemo2.java requires these files: ImageFileView.java
 * ImageFilter.java ImagePreview.java Utils.java images/jpgIcon.gif (required by
 * ImageFileView.java) images/gifIcon.gif (required by ImageFileView.java)
 * images/tiffIcon.gif (required by ImageFileView.java) images/pngIcon.png
 * (required by ImageFileView.java)
 */
public class FileChooserDemo2 extends JPanel implements ActionListener {
  static private String newline = "\n";
  private JTextArea log;
  private JFileChooser fc;

  public FileChooserDemo2() {
    super(new BorderLayout());

    // Create the log first, because the action listener
    // needs 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);

    JButton sendButton = new JButton("Attach...");
    sendButton.addActionListener(this);

    add(sendButton, BorderLayout.PAGE_START);
    add(logScrollPane, BorderLayout.CENTER);
  }

  public void actionPerformed(ActionEvent e) {
    // Set up the file chooser.
    if (fc == null) {
      fc = new JFileChooser();

      // Add a custom file filter and disable the default
      // (Accept All) file filter.
      fc.addChoosableFileFilter(new ImageFilter());
      fc.setAcceptAllFileFilterUsed(false);

      // Add custom icons for file types.
      fc.setFileView(new ImageFileView());

      // Add the preview pane.
      fc.setAccessory(new ImagePreview(fc));
    }

    // Show it.
    int returnVal = fc.showDialog(FileChooserDemo2.this, "Attach");

    // Process the results.
    if (returnVal == JFileChooser.APPROVE_OPTION) {
      File file = fc.getSelectedFile();
      log.append("Attaching file: " + file.getName() + "." + newline);
    } else {
      log.append("Attachment cancelled by user." + newline);
    }
    log.setCaretPosition(log.getDocument().getLength());

    // Reset the file chooser for the next time it's shown.
    fc.setSelectedFile(null);
  }

  /**
   * Create the GUI and show it. For thread safety, this method should be
   * invoked from the event dispatch thread.
   */
  private static void createAndShowGUI() {
    // Create and set up the window.
    JFrame frame = new JFrame("FileChooserDemo2");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    // Add content to the window.
    frame.add(new FileChooserDemo2());

    // Display the window.
    frame.pack();
    frame.setVisible(true);
  }

  public static void main(String[] args) {
    // Schedule a job for the event dispatch thread:
    // creating and showing this application's GUI.
    SwingUtilities.invokeLater(new Runnable() {
      public void run() {
        // Turn off metal's use of bold fonts
        UIManager.put("swing.boldMetal", Boolean.FALSE);
        createAndShowGUI();
      }
    });
  }
}

/*
 * Copyright (c) 1995, 2008, Oracle and/or its affiliates. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Oracle or the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

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