JPEGファイルのコメントを取り出す

InputStream source = getClass().getResourceAsStream("test.jpg");
Iterator readers = ImageIO.getImageReadersByFormatName("jpeg");
ImageReader reader = (ImageReader) readers.next();
// FileInputStream source = new FileInputStream(new File("c:/tmp/test.jpg"));
ImageInputStream iis = ImageIO.createImageInputStream(source);
reader.setInput(iis, true);

// [[MediaTrackerで画像のサイズを取得>Swing/MediaTracker]]
// ImageReadParam param = reader.getDefaultReadParam();
// buf.append(String.format("Width: %d%n", reader.getWidth(0)));
// buf.append(String.format("Height: %d%n", reader.getHeight(0)));

IIOMetadata meta = reader.getImageMetadata(0);
// for (String s: meta.getMetadataFormatNames())
//   buf.append(String.format("MetadataFormatName: %s%n",s));

IIOMetadataNode root = (IIOMetadataNode) meta.getAsTree("javax_imageio_jpeg_image_1.0");
// root = (IIOMetadataNode) meta.getAsTree("javax_imageio_1.0");

NodeList com = root.getElementsByTagName("com");
if (com != null && com.getLength() > 0) {
  String comment = ((IIOMetadataNode) com.item(0)).getAttribute("comment");
  buf.append(String.format("Comment: %s%n", comment));
}