corejava/corejava第10版/v2ch11/imageIO/ImageIOFrame.java

package imageIO;

import java.awt.image.*;
import java.io.*;
import java.util.*;

import javax.imageio.*;
import javax.imageio.stream.*;
import javax.swing.*;
import javax.swing.filechooser.*;

/**
 * This frame displays the loaded images. The menu has items for loading and saving files.
 */
public class ImageIOFrame extends JFrame
{
   private static final int DEFAULT_WIDTH = 400;
   private static final int DEFAULT_HEIGHT = 400;

   private static Set<String> writerFormats = getWriterFormats();

   private BufferedImage[] images;

   public ImageIOFrame()
   {
      setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);

      JMenu fileMenu = new JMenu("File");
      JMenuItem openItem = new JMenuItem("Open");
      openItem.addActionListener(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(event -> saveFile(formatName));
      }

      JMenuItem exitItem = new JMenuItem("Exit");
      exitItem.addActionListener(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()
   {
      Set<String> writerFormats = new TreeSet<>();
      Set<String> formatNames = new TreeSet<>(
         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;
   }
}