ajax请求java后台，返回的json数据，为何取不到值呢

html页面代码：

mui.ajax({  
                    type: "get",  
                    url: "http://192.168.0.101:8081/fzyzjk/business/app/ajaxLogin.html",  
                    async: true,  
                    data: {  
                        uphone: uphone,  
                        upassword: upwd  
                    },  
                    dataType: "json",  
                    timeout: 1000,  
                    success: function(data) {  
                        //[{"alreadyLogined":false,"defaultPassword":false,"loginSuccess":false,"permissionEntity":null,"result":0,"user":{}}]  

                        var jsdata=JSON.stringify(data);  
                        var ret=jsdata.status;  
                        console.log(ret);

以下省略
===================================================================
返回的json数据：

[{"alreadyLogined":false,"defaultPassword":false,"loginSuccess":false,"permissionEntity":null,"result":0,"user":{}}]  
var jsdata=JSON.stringify(data);  
var ret=jsdata.status;（这里ret没取到，控制台输出为：undefined）

这是为何呢？谢谢了。
================以下是java后台======================================

 String uphone = request.getParameter("uphone");  
            String upassword = request.getParameter("upassword");  

            Map userMap = appInterfaceService.getUserByLoginName(uphone);  
            Map retMap=new HashMap();  
            retMap.put("user", userMap);  
            retMap.put("status", "3");  
            //用户名不存在  
            if (userMap == null || userMap.isEmpty()) {  
                retMap.put("status",""+(LoginEntity.Login_Result_UserNameNotExists));  
            }else{  
                //用户名或密码错误  
                if (!EqualUtil.isStringEqual(userMap.get("PASSWORD"),appInterfaceService.getEncodedPassword(upassword))) {  
                    retMap.put("status",""+(LoginEntity.Login_Result_PassowrdError)+"");  
                }  
                //用户被禁用  
                if (EqualUtil.isStringEqual(userMap.get("ZT"), "2")) {  
                    retMap.put("status",""+(LoginEntity.Login_Result_LoginForbid)+"");  
                }  
            }  
            System.out.print( JsonUtil.obj2Json(retMap));  
            WebUtil.write(response, JsonUtil.obj2Json(retMap));