Spring Boot获取树状结构数据

拉斯特8个月前发布
2470

前言

在开发中，层级数据（树状结构）的获取往往可能是我们一大难点，我现在将自己获取的树状结构数据方法总结如下,希望能给有需要的小伙伴有所帮助！

一、测试数据准备

 

/*
 Navicat Premium Data Transfer

 Source Server         : 本地MySQL-local
 Source Server Type    : MySQL
 Source Server Version : 80100
 Source Host           : localhost:33306
 Source Schema         : test

 Target Server Type    : MySQL
 Target Server Version : 80100
 File Encoding         : 65001

 Date: 06/09/2023 11:21:45
*/

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for region
-- ----------------------------
DROP TABLE IF EXISTS `region`;
CREATE TABLE `region`  (
  `id` bigint(0) NOT NULL COMMENT '主键id',
  `region_id` bigint(0) NULL DEFAULT NULL COMMENT '区域id',
  `region_code` varchar(50) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin NULL DEFAULT NULL COMMENT '区域编码',
  `region_name` varchar(250) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin NULL DEFAULT NULL COMMENT '区域名称',
  `parent_id` bigint(0) NULL DEFAULT NULL COMMENT '父节点id',
  PRIMARY KEY (`id`) USING BTREE,
  UNIQUE INDEX `region_id`(`region_id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8mb4 COLLATE = utf8mb4_bin COMMENT = '地区信息' ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of region
-- ----------------------------
INSERT INTO `region` VALUES (1, 10001, 'CODEA0001', '中国', 0);
INSERT INTO `region` VALUES (2, 10002, 'CODEB0001', '安徽省', 10001);
INSERT INTO `region` VALUES (3, 10003, 'CODEB0002', '黑龙江省', 10001);
INSERT INTO `region` VALUES (4, 10004, 'CODEB0003', '广东省', 10001);
INSERT INTO `region` VALUES (5, 10005, 'CODEC0001', '合肥市', 10002);
INSERT INTO `region` VALUES (6, 10006, 'CODEC0002', '淮北市', 10002);
INSERT INTO `region` VALUES (7, 10007, 'CODEC0003', '哈尔滨市', 10003);
INSERT INTO `region` VALUES (8, 10008, 'CODEC0004', '鹤岗市', 10003);
INSERT INTO `region` VALUES (9, 10009, 'CODEC0005', '广州市', 10004);
INSERT INTO `region` VALUES (10, 10010, 'CODEC0006', '深圳市', 10004);
INSERT INTO `region` VALUES (11, 10011, 'CODED0001', '龙华区', 10010);
INSERT INTO `region` VALUES (12, 10012, 'CODED0002', '南山区', 10010);
INSERT INTO `region` VALUES (13, 10013, 'CODED0003', '天河区', 10009);

SET FOREIGN_KEY_CHECKS = 1;
 

二、对应表数据java实体类

 

import lombok.Data;
import java.util.List;

/**
 * @Project
 * @Description
 * @Author songwp
 * @Date 2023/9/5 15:16
 **/
@Data
public class Region{
    private Long id;
    private Long regionId;
    private String regionCode;
    private String regionName;
    private Long parentId;
    private List<Region> children;

}
 

三、利用<collection>标签实现；通过collection节点继续调用获取下级节点数据的方法进行循环调用

1、对应mapper的调用方法

 

import com.songwp.pojo.entity.Region;
import org.apache.ibatis.annotations.Mapper;
import java.util.List;

/**
 * @Project
 * @Description  在 持久层，我们只调用 getNodeTree 方法，parent_id = 0 代表顶级节点。 * 然后通过 collection 节点继续调用 getNextNodeTree 方法进行循环调用。
 * @Author songwp
 * @Date 2023/9/5 15:22
 **/
@Mapper
public interface RegionMapper {

    List<Region> getNodeTree();
}
 

2、对应mapper.xml的写法（重点）

  • column 代表会拿父节点 region_id ，作为参数获取 region对象
  • javaType 代表 children对象是个列表，其实可以省略不写
  • ofType 用来区分 JavaBean 属性类型和集合包含的类型
  • select 是用来执行循环哪个SQL
 

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.songwp.mapper.RegionMapper">

    <sql id="Base_Column_List">
        id,
        region_id,
        parent_id,
        region_code,
        region_name
    </sql>

    <resultMap id="BaseTreeResultMap" type="com.songwp.pojo.entity.Region">
        <result property="id" column="id" jdbcType="BIGINT"/>
        <result property="regionId" column="region_id" jdbcType="BIGINT"/>
        <result property="regionCode" column="region_code" jdbcType="VARCHAR"/>
        <result property="regionName" column="region_name" jdbcType="VARCHAR"/>
        <result property="parentId" column="parent_id" jdbcType="BIGINT"/>
        <collection column="region_id" property="children" javaType="java.util.ArrayList"
                    ofType="com.songwp.pojo.entity.Region" select="getNextNodeTree"/>
    </resultMap>

    <resultMap id="NextTreeResultMap" type="com.songwp.pojo.entity.Region">
        <result property="id" column="id" jdbcType="BIGINT"/>
        <result property="regionId" column="region_id" jdbcType="BIGINT"/>
        <result property="regionCode" column="region_code" jdbcType="VARCHAR"/>
        <result property="regionName" column="region_name" jdbcType="VARCHAR"/>
        <result property="parentId" column="parent_id" jdbcType="BIGINT"/>
        <collection column="region_id" property="children" javaType="java.util.ArrayList"
                    ofType="com.songwp.pojo.entity.Region" select="getNextNodeTree"/>
    </resultMap>

    <select id="getNextNodeTree" resultMap="NextTreeResultMap">
        SELECT
        <include refid="Base_Column_List"/>
        FROM region
        WHERE parent_id = #{id}
    </select>

    <select id="getNodeTree" resultMap="BaseTreeResultMap">
        SELECT
        <include refid="Base_Column_List"/>
        FROM region
        WHERE parent_id = 0
    </select>
</mapper>
 

3、业务方法、控制层方法代码编写

 

/**
 * @Project
 * @Description Service-业务接口
 * @Author songwp
 * @Date 2023/9/5 15:35
 **/
public interface RegionService {
    List<Region> getRegionList();
}

------------------------------------------------------------------------------------------------------/**
 * @Project
 * @Description  ServiceImpl-业务实现类
 * @Author songwp
 * @Date 2023/9/5 15:36
 **/
@Service
public class RegionServiceImpl implements RegionService {

    @Resource
    private RegionMapper regionMapper;

    @Override
    public List<Region> getRegionList() {
        return regionMapper.getNodeTree();
    }
}

-----------------------------------------------------------------------------------------------------/**
 * @Project
 * @Description Controller-控制层
 * @Author songwp
 * @Date 2023/9/5 15:39
 **/
@RestController
@RequestMapping(value = "region",produces = "application/json; charset=utf-8")
@Api(tags = "行政区划")
public class RegionController {

    @Autowired
    private RegionService regionService;

    /**
     * 查询行政区划数据
     * @param
     * @return
     */
    @GetMapping(value = "/findRegionList")
    @ApiOperation("查询行政区划数据")
    public List<Region> findRegionList(){
        return regionService.getRegionList();
    }
}
 

4、具体调用结果如下：

 

[
  {
    "id": 1,
    "regionId": 10001,
    "regionCode": "CODEA0001",
    "regionName": "中国",
    "parentId": 0,
    "children": [
      {
        "id": 2,
        "regionId": 10002,
        "regionCode": "CODEB0001",
        "regionName": "安徽省",
        "parentId": 10001,
        "children": [
          {
            "id": 5,
            "regionId": 10005,
            "regionCode": "CODEC0001",
            "regionName": "合肥市",
            "parentId": 10002,
            "children": []
          },
          {
            "id": 6,
            "regionId": 10006,
            "regionCode": "CODEC0002",
            "regionName": "淮北市",
            "parentId": 10002,
            "children": []
          }
        ]
      },
      {
        "id": 3,
        "regionId": 10003,
        "regionCode": "CODEB0002",
        "regionName": "黑龙江省",
        "parentId": 10001,
        "children": [
          {
            "id": 7,
            "regionId": 10007,
            "regionCode": "CODEC0003",
            "regionName": "哈尔滨市",
            "parentId": 10003,
            "children": []
          },
          {
            "id": 8,
            "regionId": 10008,
            "regionCode": "CODEC0004",
            "regionName": "鹤岗市",
            "parentId": 10003,
            "children": []
          }
        ]
      },
      {
        "id": 4,
        "regionId": 10004,
        "regionCode": "CODEB0003",
        "regionName": "广东省",
        "parentId": 10001,
        "children": [
          {
            "id": 9,
            "regionId": 10009,
            "regionCode": "CODEC0005",
            "regionName": "广州市",
            "parentId": 10004,
            "children": [
              {
                "id": 13,
                "regionId": 10013,
                "regionCode": "CODED0003",
                "regionName": "天河区",
                "parentId": 10009,
                "children": []
              }
            ]
          },
          {
            "id": 10,
            "regionId": 10010,
            "regionCode": "CODEC0006",
            "regionName": "深圳市",
            "parentId": 10004,
            "children": [
              {
                "id": 11,
                "regionId": 10011,
                "regionCode": "CODED0001",
                "regionName": "龙华区",
                "parentId": 10010,
                "children": []
              },
              {
                "id": 12,
                "regionId": 10012,
                "regionCode": "CODED0002",
                "regionName": "南山区",
                "parentId": 10010,
                "children": []
              }
            ]
          }
        ]
      }
    ]
  }
]
 

四、利用Java递归调用构造树状数据

1、构造树节点的实体类

 

/**
 * @Project
 * @Description
 * @Author songwp
 * @Date 2023/9/7 14:43
 **/
@Getter
@Setter
@ToString
@AllArgsConstructor
@NoArgsConstructor
public class TreeNode {
    private Long id;

    private Long parentId;

    private String name;

    private List<TreeNode> children;

    public TreeNode(long id, long parentId, String name) {
        this.id=id;
        this.parentId=parentId;
        this.name=name;
    }
}
 

2、构造树的工具类

 

/**
 * @Project
 * @Description
 * @Author songwp
 * @Date 2023/9/7 14:45
 **/
public class TreeUtils {
    public List<TreeNode> nodeList = new ArrayList<>();

    /**
     *  构造方法
     *  @param nodeList 将数据集合赋值给nodeList，即所有数据作为所有节点。
     */
    public TreeUtils(List<TreeNode> nodeList){
        this.nodeList = nodeList;
    }

    /**
     *   获取需构建的所有根节点  这里默认父节点值为"0"作为根节点
     *   @return 所有根节点List集合
     */
    public List<TreeNode> getRootNode(){
        //  rootNodeList 保存所有根节点（所有根节点的数据）
        // treeNode：查询出的每一条数据（节点）
        List<TreeNode> rootNodeList = nodeList.stream().filter(i->i.getParentId()==0).collect(Collectors.toList());
        return rootNodeList;
    }

    /**
     *  根据所有根节点进行构建树形结构
     *  @return  构建整棵树
     */
    public List<TreeNode> buildTree(){
        // treeNodes：保存一个顶级节点所构建出来的完整树形
        // getRootNode()：获取所有的根节点
        List<TreeNode> treeNodes = getRootNode().stream()
                .map(this::buildChildTree)
                .collect(Collectors.toList());
        return treeNodes;
    }

    /**
     *  递归-----构建单个子树形结构
     *  @param  pNode 根节点
     *  @return 整棵树
     */
    public TreeNode buildChildTree(TreeNode pNode){
        List<TreeNode> childTree = new ArrayList<TreeNode>();
        // nodeList：所有节点集合（所有数据）

        nodeList.stream()
                .filter(i-> i.getParentId().equals(pNode.getId()))
                .forEach(i -> childTree.add(buildChildTree(i)));
        // 处理数据结束，即节点下没有任何节点，树形构建结束，设置树结果
        pNode.setChildren(childTree);
        return pNode;
    }
}
 

3、持久层方法以及对应mapper.xml

 

 ## 返回字段
 <sql id="Base_Column_List">
        id,
        region_id,
        parent_id,
        region_code,
        region_name
   </sql>

## 获取所有数据
 <select id="selectNodeTree" resultMap="BaseTreeResultMap">
        SELECT
        <include refid="Base_Column_List"/>
        FROM region
  </select>
## mapper方法
List<Region> selectNodeTree();
 

4、业务方法及控制层方法

 

##业务方法-Service
List<TreeNode> getRegionTree();
## 业务方法具体实现-ServiceImpl
 @Override
    public List<TreeNode> getRegionTree() {
        List<TreeNode> nodes = new ArrayList<>();
        List<Region> nodeTree = regionMapper.selectNodeTree();
        if (CollectionUtil.isNotEmpty(nodeTree)) {
            for (Region region : nodeTree) {
                TreeNode node = new TreeNode();
                node.setId(region.getRegionId());
                node.setName(region.getRegionName());
                node.setParentId(region.getParentId());
                nodes.add(node);
            }
        }
        TreeUtils treeBuild = new TreeUtils(nodes);
        nodes = treeBuild.buildTree();
        return nodes;
    }
## 控制层方法-Controller
 /**
     * 查询行政区划数据
     * @param
     * @return
     */
    @GetMapping(value = "/getRegionTree")
    @ApiOperation("查询行政区划数据-方法02")
    public List<TreeNode> getRegionTree02(){
        return regionService.getRegionTree();
    }
 

5、具体调用结果如下：

[
  {
    "id": 10001,
    "parentId": 0,
    "name": "中国",
    "children": [
      {
        "id": 10002,
        "parentId": 10001,
        "name": "安徽省",
        "children": [
          {
            "id": 10005,
            "parentId": 10002,
            "name": "合肥市",
            "children": []
          },
          {
            "id": 10006,
            "parentId": 10002,
            "name": "淮北市",
            "children": []
          }
        ]
      },
      {
        "id": 10003,
        "parentId": 10001,
        "name": "黑龙江省",
        "children": [
          {
            "id": 10007,
            "parentId": 10003,
            "name": "哈尔滨市",
            "children": []
          },
          {
            "id": 10008,
            "parentId": 10003,
            "name": "鹤岗市",
            "children": []
          }
        ]
      },
      {
        "id": 10004,
        "parentId": 10001,
        "name": "广东省",
        "children": [
          {
            "id": 10009,
            "parentId": 10004,
            "name": "广州市",
            "children": [
              {
                "id": 10013,
                "parentId": 10009,
                "name": "天河区",
                "children": []
              }
            ]
          },
          {
            "id": 10010,
            "parentId": 10004,
            "name": "深圳市",
            "children": [
              {
                "id": 10011,
                "parentId": 10010,
                "name": "龙华区",
                "children": []
              },
              {
                "id": 10012,
                "parentId": 10010,
                "name": "南山区",
                "children": []
              }
            ]
          }
        ]
      }
    ]
  }
]
来源：https://www.cnblogs.com/songweipeng/p/17681897.html
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