import org.apache.commons.codec.digest.DigestUtils;

import java.awt.image.BufferedImage;
import java.awt.image.DataBuffer;
import java.awt.image.DataBufferByte;
import java.awt.image.DataBufferInt;
import java.io.File;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.IntBuffer;
import javax.imageio.ImageIO;
import javax.imageio.ImageReader;
import javax.imageio.stream.ImageInputStream;

public class JpegReaderTest {

	public static void main(String[] args)
			  throws IOException
	{
		ImageIO.setUseCache(false);

		System.setProperty("sun.java2d.cmm", "sun.java2d.cmm.kcms.KcmsServiceProvider");

		String file1 = "r:\\tmp\\001.jpg";
		String file2 = "r:\\tmp\\002.jpg";

		// test 1 - single file only, correct image is produced
		// 002.jpg = 32629496911f9addbc476ec8db564446
//		testFile(file2);

		// test 2 - 002 is loaded after 001, incorrect image is produced
		// 002.jpg = 83ba95b3d6c5b8c4c063a824666735bd
//		testFile(file1);
//		testFile(file2);
	}

	private static void testFile(String filePath)
			  throws IOException
	{
		File file  = new File(filePath);

		ImageReader reader = ImageIO.getImageReadersByFormatName("JPEG").next();
		System.out.println("Using JPEG reader: " + reader.getClass());
		try (ImageInputStream iis = ImageIO.createImageInputStream(file)) {
			reader.setInput(iis);

			BufferedImage image = reader.read(0);
			String imageMd5 = getImageMd5(image);
			System.out.println("File: " + file.getName() + " = " + imageMd5);
		}
		finally {
			reader.dispose();
		}
	}

	private static String getImageMd5(BufferedImage image) {
		byte[] data;
		DataBuffer buffer = image.getRaster().getDataBuffer();
		if (buffer instanceof DataBufferInt) {
			int[] pixels = ((DataBufferInt) buffer).getData();
			ByteBuffer byteBuffer = ByteBuffer.allocate(pixels.length * 4);
			IntBuffer intBuffer = byteBuffer.asIntBuffer();
			intBuffer.put(pixels);
			data = byteBuffer.array();
		}
		else if (buffer instanceof DataBufferByte) {
			data = ((DataBufferByte) buffer).getData();
		}
		else {
			throw new IllegalStateException("Unsupported buffer type: " + buffer);
		}

		return DigestUtils.md5Hex(data);
	}

}