Java利用TreeUtils工具類實現列表轉樹

2022-11-23 14:00:24

一、序言

在日常一線開發過程中，總有列表轉樹的需求，幾乎是專案的標配，比方說做多級選單、多級目錄、多級分類等，有沒有一種通用且跨專案的解決方式呢？幫助廣大技術朋友給業務瘦身，提高開發效率。

本文將基於Java8的Lambda 表示式和Stream等知識，使用TreeUtils工具類實現一行程式碼完成列表轉樹這一通用型需求。本文有配套視訊，傳送門直達。

需要說明的是，本TreeUtils工具類已進行三版優化，能夠勝任生產場景絕大多數列表轉樹的。

二、實戰編碼

1、引入座標

本座標地址包含TreeUtils工具類方法，已經發布到Maven中央倉庫，建議使用最新的版本號，本文釋出時版本是1.5.8.3，若有最新版本，建議使用最新版本。

學習原始碼的朋友，原始碼直通車

<dependency>
    <groupId>xin.altitude.cms</groupId>
    <artifactId>ucode-cms-common</artifactId>
    <version>1.5.8.3</version>
</dependency>

2、編寫DO

DO是存取資料庫實體類，屬於前期準備素材。

@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、建立BO

建立BO資料模型用於構造屬性結點

@Data
@NoArgsConstructor
public class CategoryBo {
    private String id;
    private String name;
    private String parentId;
    private String remark;
    /**
     * 孩子結點 名字任意取
     */
    private List<CategoryBo> childList;
    /**
     * 實現Category 轉 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、呼叫TreeUtils工具類

在服務層呼叫TreeUtils工具類，一行程式碼完成轉換。

/**
 * 獲取DO中指定的屬性 並構造成樹
 * @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

原始列表資料

{
  "code": 200,
  "msg": "操作成功",
  "data": [
    {
      "id": "310000",
      "name": "電子商務",
      "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": "大宗商品綜合",
      "parentId": "310100",
      "remark": "IIIII",
      "createTime": null,
      "updateTime": "2021-11-21 11:22:58"
    },
    {
      "id": "310102",
      "name": "鋼鐵類電商",
      "parentId": "310100",
      "remark": "OOOOO",
      "createTime": null,
      "updateTime": "2021-11-21 11:23:02"
    },
    {
      "id": "310200",
      "name": "綜合電商",
      "parentId": "310000",
      "remark": "NNNNN",
      "createTime": null,
      "updateTime": "2021-11-21 11:23:07"
    }
  ]
}

樹狀層次資料

{
  "code": 200,
  "msg": "操作成功",
  "data": [
    {
      "id": "310000",
      "name": "電子商務",
      "parentId": "000000",
      "remark": "EEEEE",
      "childList": [
        {
          "id": "310100",
          "name": "大宗商品",
          "parentId": "310000",
          "remark": "JJJJJ",
          "childList": [
            {
              "id": "310101",
              "name": "大宗商品綜合",
              "parentId": "310100",
              "remark": "IIIII",
              "childList": []
            },
            {
              "id": "310102",
              "name": "鋼鐵類電商",
              "parentId": "310100",
              "remark": "OOOOO",
              "childList": []
            }
          ]
        },
        {
          "id": "310200",
          "name": "綜合電商",
          "parentId": "310000",
          "remark": "NNNNN",
          "childList": []
        }
      ]
    }
  ]
}