底層工具類，引數為檔案流，返回也是檔案流，具體是上傳雲還是下載這裡就不寫了，主要是圖片合成

業務是一張底圖，一張或者多張子圖片，更具子圖的座標x和座標y生成圖片

PictureSynthesisSonFo 物件為子圖物件

PictureSynthesisFo 物件為底圖物件幷包含子圖物件集合

public static InputStream overlapImage(PictureSynthesisFo pictureSynthesisFo){
        InputStream is;
        try {
            //設定圖片大小
            //背景圖片
 

            BufferedImage background = ImageIO.read(pictureSynthesisFo.getInputStream());
            Graphics2D g = background.createGraphics();
            g.setRenderingHint(RenderingHints.KEY_INTERPOLATION,RenderingHints.VALUE_INTERPOLATION_BILINEAR);
            g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, 
 
1));
            for (PictureSynthesisSonFo sonFiles : pictureSynthesisFo.getSonFiles()  ) {
                BufferedImage qrCode = ImageIO.read(sonFiles.getInputStream());
                log.info("合成簽字圖fileCode:{},原width:{},width:{},原height:{},height:{}",sonFiles.getFileCode(),
                        qrCode.getWidth(),sonFiles.getWidth(),qrCode.getHeight(), sonFiles.getHeight());
                
 
//在背景圖片上新增圖片
                g.drawImage(qrCode .getScaledInstance(sonFiles.getWidth(), sonFiles.getHeight(), Image.SCALE_SMOOTH),  sonFiles.getX(), sonFiles.getY(), null);
            }
            g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER));
            g.dispose();
            ByteArrayOutputStream bs =new ByteArrayOutputStream();
            is = new ByteArrayInputStream(bs.toByteArray());
            return  is ;
        }catch (Exception e){
            LogUtil.error(log,"圖片轉換錯誤:{0}",e);
        }
        return null;
    }