xhr转json方法

xhr转json问题

	    // 定义上传对象
	    var xmlhttp;
	     // 显示确认登记单 
	    function confirmModalBlock() {
            var modal = document.getElementById('confirmModal');
            // 获取勾选的id
            var appointId;
            var items = document.getElementsByName('appointId');
            for (var i = 0; i < items.length; i++) {
                if (items[i].checked) {
                    appointId = items[i].value;
                    break;
                }
            }
            // 获取信息接口
            if (appointId != undefined) {
            	// 路径
                var url = "http://localhost:8080/getSampleAppoint?appointId=" + appointId;
                xmlhttp = new XMLHttpRequest();
                xmlhttp.onreadystatechange = checkResult;
                xmlhttp.open("GET", url, true);
                // 发送的信息
                xmlhttp.send(null);
                modal.style.display = "block";
            } else {
                alert("请选择预约单!");
            }
        }

        function checkResult() {
        	// 如果回传成功
            if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
                var result = xmlhttp.responseText;
                var json = eval("(" + result + ")");
                alert(json.data.companyName)
            }
        }

---

	// 后端接口
	@RequestMapping("getSampleAppoint")
    public ModelAndView getSampleAppoint(String appointId) {
        ModelAndView mav = new ModelAndView();

        SampleAppoint sampleAppoint = sampleAppointService.getById(appointId);
        JSONObject jsonObject = JSONObject.fromBean(sampleAppoint);
        JSONObject res = new JSONObject();
        res.put("data", jsonObject);
        mav.addObject("message", res);
        mav.setViewName("data");
        return mav;
    }