二維碼圖片流轉base64

@RequestMapping(value = "/weChatImage",method = RequestMethod.GET)
public Response weChatimage(@RequestParam(required=false) int width,@RequestParam(required=false) int height,@RequestParam(required = false) String redirect, HttpServletResponse response) throws Exception{

   String code = java.util.UUID.randomUUID().toString();
   String code_url = SystemProperties.getValue("ucenter.out.url")+"/weChat/scanCode?state="+code;
   //String code_url = "http://localhost:8080/weChat/scanCode?state="+code;
   Map<String,Object> map1 = new HashMap<>();
   map1.put("redirect",redirect);
   redis.opsForValue().set(code,JSON.toJSONString(map1),7,TimeUnit.DAYS);

   if(width == 0){
      width = 200;//寬度
   }
   if(height == 0){
      height = 200;//高度
   }

   Map<EncodeHintType,Object> hints = new HashMap<>();
   hints.put(EncodeHintType.CHARACTER_SET, "UTF-8");

   //生成矩陣
   BitMatrix bitMatrix = new MultiFormatWriter().encode(code_url, BarcodeFormat.QR_CODE, width, height, hints);

   //字節數組輸出流
   ByteArrayOutputStream imageOut = new ByteArrayOutputStream();
   MatrixToImageWriter.writeToStream(bitMatrix, "png", imageOut);

   //字節數組輸入流
   ByteArrayInputStream imageIn = new ByteArrayInputStream(imageOut.toByteArray());
   BufferedImage bImage = ImageIO.read(imageIn);

   ByteArrayOutputStream bs =new ByteArrayOutputStream();
   ImageIO.write(bImage, "png", bs);

   String base64 = "data:image/png;base64,"+Base64.byteArrayToBase64(bs.toByteArray());
   Map<String,Object> map = new HashMap<>();
   map.put("base64",base64);
   map.put("url",code_url);
   map.put("code",code);

   return Response.newInstance().setStatus(Response.SUCCESS).setBody(map);
}