项目中使用了AJAX技术，JAR包为：json-lib.jar， 在开发过程中遇到了一个JSON-LIB和Hibernate有关的问题：

net.sf.json.JSONException: There is a cycle in the hierarchy!
at net.sf.json.util.CycleDetectionStrategy$StrictCycleDetectionStrategy.handleRepeatedReferenceAsObject(CycleDetectionStrategy.

主外键关联，产生循环错误

需设置过滤，去掉关联

Java

public ModelAndView getRooms(HttpServletResponse response,@PathVariable Long hotelsid){ List<Room> roomList=roomService.findByHotelsid(hotelsid); JsonConfig jsonConfig = new JsonConfig(); jsonConfig.setJsonPropertyFilter(new net.sf.json.util.PropertyFilter(){ @Override public boolean apply(Object source,String name,Object value) { if(name.equals("hotels")){ return true; }else{ return false; } }}); JSONArray json=JSONArray.fromObject(roomList,jsonConfig); try { PrintWriter out=response.getWriter(); out.println(json.toString()); out.flush(); out.close(); } catch (IOException e) { e.printStackTrace(); } return null; }