java后端已經(jīng)寫了produces了，為什么返回到前端的還是亂碼呀？

@RequestMapping(value = "/get_all_news",method = {RequestMethod.GET, RequestMethod.POST},produces = "application/json; charset=utf-8")
    @ResponseBody
    public String get_all_news (){
        List<News>list_news =newsService.get_all_news();
        return JSON.toJSONString(list_news) ;
    }