BufferedImage bufferedImage = ImageUtil.getImageByPath("bg.png");
Graphics2D g2d = bufferedImage.createGraphics();
g2d.rotate(Math.toRadians(90), bufferedImage.getWidth() >> 1, bufferedImage.getHeight() >> 1);
g2d.dispose();

BufferedImage bufferedImage = ImageUtil.getImageByPath("bg.png");

AffineTransform tx = new AffineTransform();
tx.rotate(0.5, bufferedImage.getWidth() / 2, bufferedImage.getHeight() / 2);

AffineTransformOp op = new AffineTransformOp(tx,
        AffineTransformOp.TYPE_BILINEAR);
bufferedImage = op.filter(bufferedImage, null);