Java图片缩小后不失真的代码（缩略图）

public static void reduceImg(String imgsrc, String imgdist, int widthdist,
        int heightdist) {
    try {
        File srcfile = new File(imgsrc);
        if (!srcfile.exists()) {
            return;
        }
        Image src = javax.imageio.ImageIO.read(srcfile);

        BufferedImage tag= new BufferedImage((int) widthdist, (int) heightdist,
                BufferedImage.TYPE_INT_RGB);

        tag.getGraphics().drawImage(src.getScaledInstance(widthdist, heightdist,  Image.SCALE_SMOOTH), 0, 0,  null);
//        tag.getGraphics().drawImage(src.getScaledInstance(widthdist, heightdist,  Image.SCALE_AREA_AVERAGING), 0, 0,  null);

        FileOutputStream out = new FileOutputStream(imgdist);
        JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
        encoder.encode(tag);
        out.close();

    } catch (IOException ex) {
        ex.printStackTrace();
    }
}