Java利用TreeUtils工具类实现列表转树_开发_开发者

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www.devze.com、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;
     开发者_JS学习       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编程客栈点

@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android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": javascript"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": []
        }
      ]
    }
  ]
}