stream流实现树形菜单

树形菜单用到的类
@Data
public class MenuTree {
    private Integer id;

    private String name;

    private Integer parentId;

    private List<MenuTree> children;
}
 

public List<MenuTree> getMenuTree(){
　　 // 讲其他类转化为menuTree 自行实现方法
    List<MenuTree> menus = this.convertMenu(this.list());
　　 // 默认一级菜单的parentId为0
    List<MenuTree> list = menus.stream().filter(menu -> menu.getParentId() == 0).peek(
            menu -> menu.setChildren(getChildrens(menu, menus))
    ).collect(Collectors.toList());
    return list;
}

// 递归查询
public List<MenuTree> getChildrens(MenuTree root,List<MenuTree> menus){
    List<MenuTree> list = menus.stream().filter(menu ->
            Objects.equals(menu.getParentId(), root.getId())).map(menu -> {
        menu.setChildren(this.getChildrens(menu, menus));
        return menu;
    }).collect(Collectors.toList());
    return list;
}