SpringMVC中手动转json

单独json化一个对象，压缩为null的字段

   @RequestMapping("/todoListApproval")
    public void todoListApproval(String id, HttpServletResponse response) throws Exception {
        Object responseResult = xxxService.getById(id);
        response.setHeader("Content-Type","application/json;charset=UTF-8");
        ServletoutputStream out = response.getoutputStream();
        IoUtils.write(JSON.toJSONString(responseResult).getBytes("UTF-8"),out);
        out.flush();
    }