递归查找树形状结(利用steam流的方式)leval值标明

1.bean(根据需求创建)

@Data
public class MenuTreeDto  {
    
    private String b00;
    private String parentId;
    private String b0101;
    private int level;
    private List children;

}

 

2.控制层

@RequestMapping("/list/tree")
public Result list(){

    List entities = dictService.listWithTree();


    return Result.ok(entities);
}

 

3.业务层

@Override
public List listWithTree() {
    //1、查出所有分类
    List entities = dictService.findAll();

    //2、组装成父子的树形结构

    //2.1）、找到所有的一级分类
    List level1Menus = entities.stream().filter(MenuTreeDto ->
            MenuTreeDto.getParentId().equals("aaa")
    ).map((menu)->{
        menu.setLevel(1);
        menu.setChildren(getChildrens(menu,entities));
        return menu;
    }).
    collect(Collectors.toList());

    return level1Menus;
}

private List getChildrens(MenuTreeDto root,List all){

    List children = all.stream().filter(MenuTreeDto -> {
        return MenuTreeDto.getParentId().equals(root.getB00());
    }).map(MenuTreeDto -> {
        //1、找到子菜单
        MenuTreeDto.setLevel(root.getLevel()+1);
        MenuTreeDto.setChildren(getChildrens(MenuTreeDto,all));
        return MenuTreeDto;
    })
    .collect(Collectors.toList());

    return children;
}

4.postman测试