json of jquery

var jsonMap = {"userModel.userName":"sdfas"};
var ss = JSON.stringify(jsonMap);
$.post(
   "**.do",
   {
aaa:map
    }
);



action中：
private String aaa;
省略aaa的set，get
JSONObject j = JSONObject.fromObject(aaa);
String userName = j.getString("userModel.userName"));