java使用stream遍历树结构

@Test
public void testtree(){
//模拟从数据库查询出来
List

    //获取父节点
    List collect = menus.stream().filter(m -> m.getParentId() == 0).map(
            (m) -> {
                m.setChildList(getChildrens(m, menus));
                return m;
            }
    ).collect(Collectors.toList());
    System.out.println("-------转json输出结果-------");
    System.out.println(JSON.toJSON(collect));
}


private List getChildrens(Menu root, List all) {
    List children = all.stream().filter(m -> {
        return Objects.equals(m.getParentId(), root.getId());
    }).map(
            (m) -> {
                m.setChildList(getChildrens(m, all));
                return m;
            }
    ).collect(Collectors.toList());
    return children;
}

@Data
@Builder
public class Menu {

public List

public Menu(Integer id, String name, Integer parentId) {
    this.id = id;
    this.name = name;
    this.parentId = parentId;
}

public Menu(Integer id, String name, Integer parentId, List childList) {
    this.id = id;
    this.name = name;
    this.parentId = parentId;
    this.childList = childList;
}

}