一、序言
在日常一线开发过程中,总有列表转树
的需求,几乎是项目的标配,比方说做多级菜单、多级目录、多级分类等,有没有一种通用且跨项目的解决方式呢?帮助广大技术朋友给业务瘦身,提高开发效率。
本文将基于Java8的Lambda 表达式和Stream等知识,使用TreeUtils
工具类实现一行代码完成列表转树这一通用型需求。本文有配套视频,传送门直达。
需要说明的是,本TreeUtils工具类已进行三版优化,能够胜任生产场景绝大多数列表转树的。
二、实战编码
1、引入坐标
本坐标地址包含TreeUtils
工具类方法,已经发布到Maven中央仓库,建议使用最新的版本号,本文发布时版本是1.5.8.3
,若有最新版本,建议使用最新版本。
学习源码的朋友,源码直通车
<dependency> <groupId>xin.altitude.cms</groupId> <artifactId>ucode-cms-common</artifactId> <version>1.5.8.3</version> </dependency>
2、编写DO
DO是访问数据库实体类,属于前期准备素材。
@Data @NoArgsConstructor @AllArgsConstructor @TableName(value = "bu_category3") public class Category { private static final long serialVersionUID = 1L; @TableId(type = IdType.AUTO) private String id; private String name; private String parentId; private String remark; @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss") private LocalDateTime createTime; @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss") private LocalDateTime updateTime; public Category(Category category) { if (Objects.nonNull(category)) { this.id = category.id; this.name = category.name; this.parentId = category.parentId; this.remark = category.remark; this.createTime = category.createTime; this.updateTime = category.updateTime; } } }
3、创建BO
创建BO数据模型用于构造属性结点
@Data @NoArgsConstructor public class CategoryBo { private String id; private String name; private String parentId; private String remark; /** * 孩子结点 名字任意取 */ private List<CategoryBo> childList; /** * 实现Category 转 CategoryBo * * @param category */ public CategoryBo(Category category) { if (Objects.nonNull(category)) { this.id = category.getId(); this.name = category.getName(); this.parentId = category.getParentId(); this.remark = category.getRemark(); } } }
3、调用TreeUtils工具类
在服务层调用TreeUtils工具类,一行代码完成转换。
/** * 获取DO中指定的属性 并构造成树 * @return */ public List<CategoryBo> selectCategory4() { List<Category> categoryList = this.list(); List<CategoryBo> categoryBoList = EntityUtils.toList(categoryList, CategoryBo::new); return TreeUtils.createNodeDetail(categoryBoList, "000000", CategoryBo::getId, CategoryBo::getParentId, CategoryBo::getChildList); }
4、效果展示
原始列表数据
{ "code": 200, "msg": "操作成功", "data": [ { "id": "310000", "name": "电子商务", "parentId": "000000", "remark": "EEEEE", "createTime": null, "updateTime": "2021-11-21 11:22:40" }, { "id": "310100", "name": "大宗商品", "parentId": "310000", "remark": "JJJJJ", "createTime": null, "updateTime": "2021-11-21 11:22:52" }, { "id": "310101", "name": "大宗商品综合", "parentId": "310100", "remark": "IIIII", "createTime": null, "updateTime": "2021-11-21 11:22:58" }, { "id": "310102", "name": "钢铁类电商", "parentId": "310100", "remark": "OOOOO", "createTime": null, "updateTime": "2021-11-21 11:23:02" }, { "id": "310200", "name": "综合电商", "parentId": "310000", "remark": "NNNNN", "createTime": null, "updateTime": "2021-11-21 11:23:07" } ] }
树状层次数据
{ "code": 200, "msg": "操作成功", "data": [ { "id": "310000", "name": "电子商务", "parentId": "000000", "remark": "EEEEE", "childList": [ { "id": "310100", "name": "大宗商品", "parentId": "310000", "remark": "JJJJJ", "childList": [ { "id": "310101", "name": "大宗商品综合", "parentId": "310100", "remark": "IIIII", "childList": [] }, { "id": "310102", "name": "钢铁类电商", "parentId": "310100", "remark": "OOOOO", "childList": [] } ] }, { "id": "310200", "name": "综合电商", "parentId": "310000", "remark": "NNNNN", "childList": [] } ] } ] }
三、小结
通过一个小小的高频业务场景,抽离业务共性,屏蔽业务细节,实现了通用型业务逻辑的编码。
希望广大技术朋友在完成日常开发工作的前提下,能够进一步打磨代码,感受编程之美。