JSONObject obj=new JSONObject();

obj.put("password","123");

obj.put("test","123222");

String a=obj.toString();

obj.put("params",a.substring(1,a.length()-1));

System.out.println(obj);

{"password":"123","test":"123222","params":"\"password\":\"123\",\"test\":\"123222\""}

在JSON里面再加入一次JSON就会自动转义