Java/JSP - สอบถามเกี่ยวกับการแปลง จากรูปภาพ type gif เป็น Base64 String ครับ

import java.io.IOException;

import sun.misc.BASE64Encoder;
import sun.misc.BASE64Decoder;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.awt.image.BufferedImage;
import javax.imageio.ImageIO;

public class ImageUtils {

	/**
	 * Decode string to image
	 * @param imageString The string to decode
	 * @return decoded image
	 */
	public static BufferedImage decodeToImage(String imageString) {

		BufferedImage image = null;
		byte[] imageByte;
		try {
			BASE64Decoder decoder = new BASE64Decoder();
			imageByte = decoder.decodeBuffer(imageString);
			ByteArrayInputStream bis = new ByteArrayInputStream(imageByte);
			image = ImageIO.read(bis);
			bis.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
		return image;
	}

	/**
	 * Encode image to string
	 * @param image The image to encode
	 * @param type jpeg, bmp, ...
	 * @return encoded string
	 */
	public static String encodeToString(BufferedImage image, String type) {
		String imageString = null;
		ByteArrayOutputStream bos = new ByteArrayOutputStream();

		try {
			ImageIO.write(image, type, bos);
			byte[] imageBytes = bos.toByteArray();

			BASE64Encoder encoder = new BASE64Encoder();
			imageString = encoder.encode(imageBytes);

			bos.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
		return imageString;
	}

	public static void main (String args[]) throws IOException {
		/* Test image to string and string to image start */
		BufferedImage img = ImageIO.read(new File("files/img/TestImage.png"));
		BufferedImage newImg;
		String imgstr;
		imgstr = encodeToString(img, "png");
		System.out.println(imgstr);
		newImg = decodeToImage(imgstr);
		ImageIO.write(newImg, "png", new File("files/img/CopyOfTestImage.png"));
		/* Test image to string and string to image finish */
	}
}