问题起因：今天在做一个EasyUI 同步树的时候,在SpringMVC中用 @ResponseBody标签将List<tree> 集合转换成Json数据的时候，出现一些原因。

问题描述：1、tree对象有个List<tree>属性需要为空，这个是做树用的，下级没值当然不能有null了

代码：

[{"id":1,"text":"权限管理 ","state":"closed  ","pid":-1,"children":[{"id":2,"text":"菜单管理","state":"open","pid":1,"children":null},{"id":3,"text":"角色管理","state":"open","pid":1,"children":null},{"id":4,"text":"用户管理","state":"open","pid":1,"children":null}]},{"id":5,"text":"33","state":"open","pid":-1,"children":null}] 解决方法；在实体类上使用 @JsonSerialize(include=JsonSerialize.Inclusion.NON_NULL) 标签 就解决了！ 加上标签后： [{"id":1,"text":"权限管理 ","state":"closed  ","pid":-1,"children":[{"id":2,"text":"菜单管理","state":"open","pid":1},{"id":3,"text":"角色管理","state":"open","pid":1},{"id":4,"text":"用户管理","state":"open","pid":1}]},{"id":5,"text":"33","state":"open","pid":-1}]