Java tutorial
/* This program is a part of the companion code for Core Java 8th ed. (http://horstmann.com/corejava) This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. */ import java.awt.EventQueue; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.image.BufferedImage; import java.io.File; import java.io.IOException; import java.util.Arrays; import java.util.Iterator; import java.util.Set; import java.util.TreeSet; import javax.imageio.IIOImage; import javax.imageio.ImageIO; import javax.imageio.ImageReader; import javax.imageio.ImageWriter; import javax.imageio.stream.ImageInputStream; import javax.imageio.stream.ImageOutputStream; import javax.swing.Box; import javax.swing.ImageIcon; import javax.swing.JFileChooser; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JMenu; import javax.swing.JMenuBar; import javax.swing.JMenuItem; import javax.swing.JOptionPane; import javax.swing.JScrollPane; import javax.swing.filechooser.FileNameExtensionFilter; /** * This program lets you read and write image files in the formats that the JDK supports. Multi-file * images are supported. * @version 1.02 2007-08-16 * @author Cay Horstmann */ public class ImageIOTest { public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { public void run() { JFrame frame = new ImageIOFrame(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setVisible(true); } }); } } /** * This frame displays the loaded images. The menu has items for loading and saving files. */ class ImageIOFrame extends JFrame { public ImageIOFrame() { setTitle("ImageIOTest"); setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT); JMenu fileMenu = new JMenu("File"); JMenuItem openItem = new JMenuItem("Open"); openItem.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent event) { openFile(); } }); fileMenu.add(openItem); JMenu saveMenu = new JMenu("Save"); fileMenu.add(saveMenu); Iterator<String> iter = writerFormats.iterator(); while (iter.hasNext()) { final String formatName = iter.next(); JMenuItem formatItem = new JMenuItem(formatName); saveMenu.add(formatItem); formatItem.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent event) { saveFile(formatName); } }); } JMenuItem exitItem = new JMenuItem("Exit"); exitItem.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent event) { System.exit(0); } }); fileMenu.add(exitItem); JMenuBar menuBar = new JMenuBar(); menuBar.add(fileMenu); setJMenuBar(menuBar); } /** * Open a file and load the images. */ public void openFile() { JFileChooser chooser = new JFileChooser(); chooser.setCurrentDirectory(new File(".")); String[] extensions = ImageIO.getReaderFileSuffixes(); chooser.setFileFilter(new FileNameExtensionFilter("Image files", extensions)); int r = chooser.showOpenDialog(this); if (r != JFileChooser.APPROVE_OPTION) return; File f = chooser.getSelectedFile(); Box box = Box.createVerticalBox(); try { String name = f.getName(); String suffix = name.substring(name.lastIndexOf('.') + 1); Iterator<ImageReader> iter = ImageIO.getImageReadersBySuffix(suffix); ImageReader reader = iter.next(); ImageInputStream imageIn = ImageIO.createImageInputStream(f); reader.setInput(imageIn); int count = reader.getNumImages(true); images = new BufferedImage[count]; for (int i = 0; i < count; i++) { images[i] = reader.read(i); box.add(new JLabel(new ImageIcon(images[i]))); } } catch (IOException e) { JOptionPane.showMessageDialog(this, e); } setContentPane(new JScrollPane(box)); validate(); } /** * Save the current image in a file * @param formatName the file format */ public void saveFile(final String formatName) { if (images == null) return; Iterator<ImageWriter> iter = ImageIO.getImageWritersByFormatName(formatName); ImageWriter writer = iter.next(); JFileChooser chooser = new JFileChooser(); chooser.setCurrentDirectory(new File(".")); String[] extensions = writer.getOriginatingProvider().getFileSuffixes(); chooser.setFileFilter(new FileNameExtensionFilter("Image files", extensions)); int r = chooser.showSaveDialog(this); if (r != JFileChooser.APPROVE_OPTION) return; File f = chooser.getSelectedFile(); try { ImageOutputStream imageOut = ImageIO.createImageOutputStream(f); writer.setOutput(imageOut); writer.write(new IIOImage(images[0], null, null)); for (int i = 1; i < images.length; i++) { IIOImage iioImage = new IIOImage(images[i], null, null); if (writer.canInsertImage(i)) writer.writeInsert(i, iioImage, null); } } catch (IOException e) { JOptionPane.showMessageDialog(this, e); } } /** * Gets a set of "preferred" format names of all image writers. The preferred format name is the * first format name that a writer specifies. * @return the format name set */ public static Set<String> getWriterFormats() { TreeSet<String> writerFormats = new TreeSet<String>(); TreeSet<String> formatNames = new TreeSet<String>(Arrays.asList(ImageIO.getWriterFormatNames())); while (formatNames.size() > 0) { String name = formatNames.iterator().next(); Iterator<ImageWriter> iter = ImageIO.getImageWritersByFormatName(name); ImageWriter writer = iter.next(); String[] names = writer.getOriginatingProvider().getFormatNames(); String format = names[0]; if (format.equals(format.toLowerCase())) format = format.toUpperCase(); writerFormats.add(format); formatNames.removeAll(Arrays.asList(names)); } return writerFormats; } private BufferedImage[] images; private static Set<String> writerFormats = getWriterFormats(); private static final int DEFAULT_WIDTH = 400; private static final int DEFAULT_HEIGHT = 400; }