Question

There is a cycle in the hierarchy!

List<Resource> res = resourceService.findAll();
JSONArray datalist = JSONArray.fromObject(res);//这里报错there is a cycle in the hierarchy

用网上提供的方法不好使
下面是Resource属性
private Integer id;
private String title;
private String description;
private Set<Role> roles = new HashSet<Role>();

Resource和Role有多对多的关系
Role的属性
private Integer id;
private String roleName;
private Set<Resource> res = new HashSet<Resource>();

Answer 1

有把有关联的属性放到json数组中就可以了。因为Resource的json数组中有roles数组，而且roles的数组元素中又有Resource数组，死循环了。用JSONConfig把roles去除就可以了。