Java实现多级菜单（递归）

实现3级分类效果如图

菜单管理数据库设计

CREATE TABLE `pms_category` (
  `cat_id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT '分类id',
  `name` char(50) DEFAULT NULL COMMENT '分类名称',
  `parent_cid` bigint(20) DEFAULT NULL COMMENT '父分类id',
  `cat_level` int(11) DEFAULT NULL COMMENT '层级',
  `show_status` tinyint(4) DEFAULT NULL COMMENT '是否显示[0-不显示，1显示]',
  `sort` int(11) DEFAULT NULL COMMENT '排序',
  `icon` char(255) DEFAULT NULL COMMENT '图标地址',
  `product_unit` char(50) DEFAULT NULL COMMENT '计量单位',
  `product_count` int(11) DEFAULT NULL COMMENT '商品数量',
  PRIMARY KEY (`cat_id`) USING BTREE,
  KEY `parent_cid` (`parent_cid`) USING BTREE
) ENGINE=InnoDB AUTO_INCREMENT=1437 DEFAULT CHARSET=utf8mb4 ROW_FORMAT=DYNAMIC COMMENT='商品三级分类';

菜单管理实体类

@Data
@TableName("pms_category")
public class CategoryEntity implements Serializable {
	private static final long serialVersionUID = 1L;

	
	@TableId
	private Long catId;
	
	private String name;
	
	private Long parentCid;
	
	private Integer catLevel;
	
	private Integer showStatus;
	
	private Integer sort;
	
	private String icon;
	
	private String productUnit;
	
	private Integer productCount;

	
	@TableField(exist = false)
	private List children;

}

Controller层

@RestController
@RequestMapping("product/category")
public class CategoryController {
    @Autowired
    private CategoryService categoryService;

    
    @RequestMapping("/list/tree")
    public R list(){
        List entityList = categoryService.listwitTree();

        return R.ok().put("data", entityList);
    }
}    

Service接口

public interface CategoryService extends IService {

	//三级菜单分类树
    List listwitTree();
}

Service接口实现类

@Service("categoryService")
public class CategoryServiceImpl extends ServiceImpl implements CategoryService {
    @Override
    public List listwitTree() {
        //1.查出所有分类
        List entities = baseMapper.selectList(null);
        //2.组装成父子树形结构

        //2.1)、找到所有的一级分类
        List level1Menus = entities.stream().filter((categoryEntity) -> {
            return categoryEntity.getParentCid() == 0;
        }).map((menu)->{
            menu.setChildren(getchildren(menu,entities));
            return menu;
        }).sorted((menu1,menu2)->{
            return (menu1.getSort()==null?0:menu1.getSort()) - (menu2.getSort()==null?0:menu2.getSort());
        }).collect(Collectors.toList());
        return level1Menus;
    }

    //递归查找所有菜单的子菜单
    private List getchildren(CategoryEntity root,List all){
        List children = all.stream().filter((categoryEntity) -> {
            return categoryEntity.getParentCid() == root.getCatId();
        }).map((categoryEntity) -> {
            //1.找到子菜单
            categoryEntity.setChildren(getchildren(categoryEntity,all));
            return categoryEntity;
        }).sorted((menu1,menu2)->{
            //2.菜单的排序
            return (menu1.getSort()==null?0:menu1.getSort()) - (menu2.getSort()==null?0:menu2.getSort());
        }).collect(Collectors.toList());
        return children;
    }

}

返回成功的Json对象

{
  "msg": "success",
  "code": 0,
  "data": [
    {
      "catId": 2,
      "name": "手机",
      "parentCid": 0,
      "catLevel": 1,
      "showStatus": 1,
      "sort": 0,
      "icon": null,
      "productUnit": null,
      "productCount": 0,
      "children": [
        {
          "catId": 34,
          "name": "手机通讯",
          "parentCid": 2,
          "catLevel": 2,
          "showStatus": 1,
          "sort": 0,
          "icon": null,
          "productUnit": null,
          "productCount": 0,
          "children": [
            {
              "catId": 225,
              "name": "手机",
              "parentCid": 34,
              "catLevel": 3,
              "showStatus": 1,
              "sort": 0,
              "icon": "",
              "productUnit": null,
              "productCount": 0,
              "children": []
            }
          ]
        }
      ]
    }
  ]
}