code: public Img rotate(int degree) {
  		final BufferedImage image = getValidSrcImg();
  		int width = image.getWidth(null);
  		int height = image.getHeight(null);
  		final Rectangle rectangle = calcRotatedSize(width, height, degree);
  		final BufferedImage targetImg = new BufferedImage(rectangle.width, rectangle.height, getTypeInt());
  		Graphics2D graphics2d = targetImg.createGraphics();
  		// 抗锯齿
  		graphics2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
  		// 从中心旋转
  		graphics2d.translate((rectangle.width - width) / 2, (rectangle.height - height) / 2);
  		graphics2d.rotate(Math.toRadians(degree), width / 2, height / 2);
  		graphics2d.drawImage(image, 0, 0, null);
  		graphics2d.dispose();
  		this.targetImage = targetImg;
  		return this;
  	}
docs: 旋转图片为指定角度<br>
  来自：http://blog.51cto.com/cping1982/130066
  
  @param degree 旋转角度
  @return 旋转后的图片
  @since 3.2.2