Get image size from file

ImDim.java

import javax.imageio.ImageIO;
import javax.imageio.ImageReader;
import javax.imageio.stream.FileImageInputStream;
import javax.imageio.stream.ImageInputStream;
import java.awt.*;
import java.io.File;
import java.io.IOException;
import java.util.Iterator;

/**
 * Utility to get the dimensions of an image without reading it all into memory.
 */
public class ImDim {

    /**
     * Demonstrates use from the command-line.
     *
     * First arg is a filename, remaining optional args are mime types.
     * Output is a single line of the form "width height".
     */
    public static void main(final String[] args) {
        try {
            if (args.length < 1) {
                System.err.println("Usage: ImDim path/to/file [mime/type1, [mime/type2], ..]");
                System.exit(1);
            }
            final String[] mimeTypes = new String[args.length - 1];
            System.arraycopy(args, 1, mimeTypes, 0, args.length - 1);
            final Dimension dim = getDimensions(new File(args[0]), mimeTypes);
            System.out.println((int) dim.getWidth() + " " + (int) dim.getHeight());
        } catch (final Exception e) {
            if (e instanceof IOException) {
                System.err.println("Error: " + e.getMessage());
            } else {
                e.printStackTrace();
                System.err.println("Error: See above.");
            }
            System.exit(1);
        }
    }

    /**
     * Gets the dimensions of the given file.
     *
     * @param file the file.
     * @param mimeTypes the optional known mime type(s).
     * @return the dimensions.
     * @throws IOException if there was an error reading the file or no suitable reader could be found.
     */
    public static Dimension getDimensions(final File file, String... mimeTypes) throws IOException {
        if (!file.isFile()) {
            throw new IOException("No such file: " + file);
        }
        final ImageReader reader = getReader(file, mimeTypes);
        try {
            final ImageInputStream stream = new FileImageInputStream(file);
            reader.setInput(stream);
            return new Dimension(reader.getWidth(reader.getMinIndex()), reader.getHeight(reader.getMinIndex()));
        } finally {
            reader.dispose();
        }
    }

    private static ImageReader getReader(final File file, String... mimeTypes) throws IOException {
        for (final String mimeType : mimeTypes) {
            Iterator<ImageReader> iter = ImageIO.getImageReadersByMIMEType(mimeType);
            if (iter.hasNext()) {
                return iter.next();
            }
        }
        String suffix = getExtension(file);
        if (suffix != null) {
            Iterator<ImageReader> iter = ImageIO.getImageReadersBySuffix(getExtension(file));
            if (iter.hasNext()) {
                return iter.next();
            }
        }
        throw new IOException("No suitable image reader found for " + file.getName());
    }

    private static String getExtension(final File file) {
        final int i = file.getName().lastIndexOf('.');
        if (i > -1) {
            return file.getName().substring(i + 1);
        }
        return null;
    }
}