java上传图片功能，改变图片大小。

Question

http://haohaoxuexi.iteye.com/blog/1187394
可以参考下

Answer 1

@SuppressWarnings("finally")
    public static byte[] scale(byte[] bytes , double width, double height) {
        BufferedImage bufferedImage = null;
        BufferedImage bufTarget = null;
        try {
            ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
            bufferedImage = ImageIO.read(bais);
            double sx =  width / bufferedImage.getWidth();
            double sy =  height / bufferedImage.getHeight();
            int type = bufferedImage.getType();
            if (type == BufferedImage.TYPE_CUSTOM) {
                ColorModel cm = bufferedImage.getColorModel();
                WritableRaster raster = cm.createCompatibleWritableRaster((int)width, (int)height);
                boolean alphaPremultiplied = cm.isAlphaPremultiplied();
                bufTarget = new BufferedImage(cm, raster, alphaPremultiplied, null);
            } else {
                bufTarget = new BufferedImage((int)width, (int)height, type);
            }
            
            Graphics2D g = bufTarget.createGraphics();
            g.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
            g.drawRenderedImage(bufferedImage, AffineTransform.getScaleInstance(sx, sy));
            g.dispose();
            
            if(bufTarget != null){
                ByteArrayOutputStream baos = new ByteArrayOutputStream();
                ImageIO.write(bufTarget, "jpeg", baos);
                byte[] result = baos.toByteArray();
                return result;
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }
图片压缩,把图片的byte字节和需要重新生成的大小传递进来即可.

Answer 2

图片压缩，如果采用zip类型的压缩的话，那么其效率确实不高，你可以采用其他的先压缩在上传，或者是切割上传，然后在后台进行组装