Java 实现图片压缩的两种方法

    /**
	 * compressImage
	 * 
	 * @param imageByte
	 *      Image source array
	 * @param ppi
	 * @return
	 */
	public static byte[] compressImage(byte[] imageByte, int ppi) {
		byte[] smallImage = null;
		int width = 0, height = 0;
 
		if (imageByte == null)
			return null;
 
		ByteArrayInputStream byteInput = new ByteArrayInputStream(imageByte);
		try {
			Image image = ImageIO.read(byteInput);
			int w = image.getWidth(null);
			int h = image.getHeight(null);
			// adjust weight and height to avoid image distortion
			double scale = 0;
			scale = Math.min((float) ppi / w, (float) ppi / h);
			width = (int) (w * scale);
			width -= width % 4;
			height = (int) (h * scale);
 
			if (scale >= (double) 1)
				return imageByte;
 
			BufferedImage buffImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
			buffImg.getGraphics().drawImage(image.getScaledInstance(width, height, Image.SCALE_SMOOTH), 0, 0, null);
			ByteArrayOutputStream out = new ByteArrayOutputStream();
			ImageIO.write(buffImg, "png", out);
			smallImage = out.toByteArray();
			return smallImage;
 
		} catch (IOException e) {
			log.error(e.getMessage());
			throw new RSServerInternalException("");
		}
	}

BufferedImage buffImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
buffImg.getGraphics().drawImage(image.getScaledInstance(width, height, Image.SCALE_SMOOTH), 0, 0, null);

    /**
	 * compressImage
	 * 
	 * @param path
	 * @param ppi
	 * @return
	 */
	public static byte[] compressImage(String path, int ppi) {
		byte[] smallImage = null;
 
	  try {
	    ByteArrayOutputStream out = new ByteArrayOutputStream();
		Thumbnails.of(path).size(ppi, ppi).outputFormat("png").toOutputStream(out);
		smallImage = out.toByteArray();
		return smallImage;
	  } catch (IOException e) {
		log.error(e.getMessage());
		throw new RSServerInternalException("");
	  }
	}