graphics 切圆背景透明

 public static String fileUploadL(MultipartFile file, String path){
        String extName = file.getOriginalFilename().substring(file.getOriginalFilename().lastIndexOf("."));
        String fileName = System.currentTimeMillis()+extName;
        
        String finalPath = BASE_PATH+path;
        try { 
            logger.info("==========储存路径"+finalPath);
            //文件夹不存在则创建文件夹
            File filepath = new File(finalPath);
            if (!filepath.exists()) {
                logger.info("==========创建文件夹");
                filepath.mkdirs();
            }
            //文件保存路径  
            String savePath = filepath+ "/" + fileName; 
            logger.info("==========全路径"+savePath);
            //转存文件  
            //file.transferTo(new File(savePath));
            logger.info("==========访问路径"+ACCESS_PATH+path+fileName);
            //multipartFile转File
            CommonsMultipartFile cf= (CommonsMultipartFile)file; 
            DiskFileItem fi = (DiskFileItem)cf.getFileItem(); 

            File f = fi.getStoreLocation();

            BufferedImage bi1 = ImageIO.read(f);
                // 根据需要是否使用 BufferedImage.TYPE_INT_ARGB

　　　　　　　　　　//设置以最小的边截取
                int num =0;
                if(bi1.getWidth()>bi1.getHeight()) {
                    num = bi1.getHeight();
                }else {
                    num = bi1.getWidth();
                }
                BufferedImage image = new BufferedImage(num,num, BufferedImage.TYPE_4BYTE_ABGR);
         
                Graphics2D g2 = image.createGraphics();
                g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
                Ellipse2D.Double shape = new Ellipse2D.Double(0, 0, num, num);
                g2.setClip(shape);
                // 使用 setRenderingHint 设置抗锯齿
                g2.drawImage(bi1, 0, 0, null);
                g2.dispose();
                ImageIO.write(resize(100, 100, image), "PNG", new File(savePath));
                return ACCESS_PATH+path+fileName;
        } catch (Exception e) {  
            e.printStackTrace();  
        }
        return null;
    }
　　//设置图片px
    public static BufferedImage resize(int targetWidth, int targetHeight,
            BufferedImage src) {
        double scaleW = (double) targetWidth / (double) src.getWidth() ;
        double scaleH = (double) targetHeight / (double) src.getHeight() ;

        double scale = scaleW < scaleH ? scaleW : scaleH;

        BufferedImage result = new BufferedImage((int) (src.getWidth() * scale),
                (int) (src.getHeight() * scale), BufferedImage.TYPE_INT_ARGB);

    Graphics2D g2d = result.createGraphics();
        g2d.drawImage(src, 0, 0, result.getWidth(), result.getHeight(), null);
        g2d.dispose();

        return result;
    }