mui.getJSONP

前端：

mui.getJSONP('http://ip地址:8080/fund-trade-web/common/fromAppJsonP', data, function(data) {  
                alert(111)  
            });

后台是java，可以进入后端，但是返回无法进入回调函数，是怎么回事呢？
后端：

@RequestMapping(value = "/fromAppJsonP", method = { RequestMethod.POST,  
            RequestMethod.GET })  
    public @ResponseBody String fromAppJsonP(HttpServletRequest request,HttpServletResponse response, @RequestParam String callback) {  
        long start = System.currentTimeMillis();  
        logger.info("fromAppP start: " + start);  
        String name = request.getParameter("name").toString();  
        String code = request.getParameter("code").toString();  
        String result =  "{'ret':'true'}";  

        result = callback + "("+result+")" ;  

        return result;  
    }