--add JpgUtil.scalingZoom()

jfwUtil/src/main/java/org/jfw/util/JpgUtil.java

@@ -115,6 +115,23 @@ public final class JpgUtil {
		Itemp = ato.filter(bufImg, null);
		return ImageIO.write((BufferedImage) Itemp, JPG, dest);
	}
	
	/**
	 * 图片等比缩放
	 * @param in 输入流
	 * @param out 输出流
	 * @param maxLen 图片较长的一边
	 * @return
	 * @throws IOException
	 */
	public static boolean scalingZoom(InputStream in,OutputStream out, int maxLen) throws IOException{
		BufferedImage bi = ImageIO.read(in);
		double max = bi.getWidth()>bi.getHeight()?bi.getWidth():bi.getHeight();
	    double scaling = maxLen/max;
	    AffineTransformOp ato = new AffineTransformOp(AffineTransform.getScaleInstance(scaling,scaling), null);
		Image Itemp = ato.filter(bi, null);
		return ImageIO.write((BufferedImage) Itemp, JPG, out);
	}
	private JpgUtil() {
	}