java处理图片按比例缩放效能

    /*     * 图片缩放,w，h为缩放的目标宽度和高度     * src为源文件目录，dest为缩放后保存目录     */    public static void zoomImage(String src,String dest,int w,int h) throws Exception {                double wr=0,hr=0;        File srcFile = new File(src);        File destFile = new File(dest);        BufferedImage bufImg = ImageIO.read(srcFile); //读取图片        Image Itemp = bufImg.getScaledInstance(w, h, bufImg.SCALE_SMOOTH);//设置缩放目标图片模板                wr=w*1.0/bufImg.getWidth();     //获取缩放比例        hr=h*1.0 / bufImg.getHeight();        AffineTransformOp ato = new AffineTransformOp(AffineTransform.getScaleInstance(wr, hr), null);        Itemp = ato.filter(bufImg, null);        try {            ImageIO.write((BufferedImage) Itemp,dest.substring(dest.lastIndexOf(".")+1), destFile); //写入缩减后的图片        } catch (Exception ex) {            ex.printStackTrace();        }    }

       /*     * 图片按比率缩放     * size为文件大小     */    public static void zoomImage(String src,String dest,Integer size) throws Exception {        File srcFile = new File(src);        File destFile = new File(dest);                long fileSize = srcFile.length();        if(fileSize < size * 1024)   //文件大于size k时，才进行缩放,注意：size以K为单位            return;                Double rate = (size * 1024 * 0.5) / fileSize; // 获取长宽缩放比例                BufferedImage bufImg = ImageIO.read(srcFile);        Image Itemp = bufImg.getScaledInstance(bufImg.getWidth(), bufImg.getHeight(), bufImg.SCALE_SMOOTH);                    AffineTransformOp ato = new AffineTransformOp(AffineTransform.getScaleInstance(rate, rate), null);        Itemp = ato.filter(bufImg, null);        try {            ImageIO.write((BufferedImage) Itemp,dest.substring(dest.lastIndexOf(".")+1), destFile);        } catch (Exception ex) {            ex.printStackTrace();        }    }