code: public Img scale(int width, int height) {
  		final BufferedImage srcImg = getValidSrcImg();
  		int srcHeight = srcImg.getHeight();
  		int srcWidth = srcImg.getWidth();
  		int scaleType;
  		if (srcHeight == height && srcWidth == width) {
  			// 源与目标长宽一致返回原图
  			this.targetImage = srcImg;
  			return this;
  		} else if (srcHeight < height || srcWidth < width) {
  			// 放大图片使用平滑模式
  			scaleType = Image.SCALE_SMOOTH;
  		} else {
  			scaleType = Image.SCALE_DEFAULT;
  		}
  		final Image image = srcImg.getScaledInstance(width, height, scaleType);
  		this.targetImage = ImgUtil.toBufferedImage(image);
  		return this;
  	}
docs: 缩放图像（按长宽缩放）<br>
  注意：目标长宽与原图不成比例会变形
  
  @param width 目标宽度
  @param height 目标高度
  @return this