springboot+mybatis plus实现树形结构查询

2024-04-02 19:04:59 815人浏览安东尼

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摘要

目录背景使用场景设计思路递归模型实现代码注意事项总结背景实际开发过程中经常需要查询节点树,根据指定节点获取子节点列表,以下记录了获取节点树的操作,以备不时之需。使

背景

实际开发过程中经常需要查询节点树,根据指定节点获取子节点列表,以下记录了获取节点树的操作,以备不时之需。

使用场景

可以用于系统部门组织机构、商品分类、城市关系等带有层级关系的数据结构；

设计思路

递归模型

即根节点、枝干节点、叶子节点，数据模型如下：

id	code	name	parent_code
1	10000	电脑	0
2	20000	手机	0
3	10001	联想笔记本	10000
4	10002	惠普笔记本	10000
5	1000101	联想拯救者	10001
6	1000102	联想小新系列	10001

实现代码

表结构


CREATE TABLE `tree_table` (
  `id` int NOT NULL AUTO_INCREMENT COMMENT '主键ID',
  `code` varchar(10) NOT NULL COMMENT '编码',
  `name` varchar(20) NOT NULL COMMENT '名称',
  `parent_code` varchar(10)  NOT NULL COMMENT '父级编码',
  PRIMARY KEY (`id`) USING BTREE
) ENGINE=MyISAM AUTO_INCREMENT=1 DEFAULT CHARSET=utf8 ROW_FORMAT=DYNAMIC COMMENT='树形结构测试表';

表数据


INSERT INTO `tree_table`(`code`, `name`, `parent_code`) VALUES ('10000', '电脑', '0');
INSERT INTO `tree_table`(`code`, `name`, `parent_code`) VALUES ('10001', '联想笔记本', '10000');
INSERT INTO `tree_table`(`code`, `name`, `parent_code`) VALUES ('10002', '惠普笔记本', '10000');
INSERT INTO `tree_table`(`code`, `name`, `parent_code`) VALUES ('1000101', '联想拯救者', '10001');
INSERT INTO `tree_table`(`code`, `name`, `parent_code`) VALUES ('1000102', '联想小新系列', '10001');

实体


@Data
@TableName("tree_table")
@EqualsAndHashCode(callSuper = false)
@Accessors(chain = true)
public class TreeTable {

    
    @TableId(type = IdType.AUTO)
    private Integer id;
    
    private String code;
    
    private String name;
    
    private String parentCode;

    
    @TableField(exist = false)
    private List<TreeTable> childnode;
}

mybatis

mapper


public interface TreeTableMapper extends BaseMapper<TreeTable> {
    
    public List<TreeTable> noteTree();
}

xml


<?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.SpringBoot.example.Mysqltree.mapper.TreeTableMapper">
    <resultMap id="BaseResultMap" type="com.springboot.example.mysqltree.model.entity.TreeTable">
        <result column="id" property="id"/>
        <result column="code" property="code"/>
        <result column="name" property="name"/>
        <result column="parent_code" property="parentCode"/>
    </resultMap>
    <resultMap id="NodeTreeResult" type="com.springboot.example.mysqltree.model.entity.TreeTable"
               extends="BaseResultMap">
        <collection property="childNode" column="code" ofType="com.springboot.example.mysqltree.model.entity.TreeTable"
                    javaType="java.util.ArrayList" select="nextNoteTree">

        </collection>
    </resultMap>

    <sql id="Base_Column_List">
                id,
                code,
                `name`,
                parent_code
    </sql>
   
    <select id="nextNoteTree" resultMap="NodeTreeResult">
        select
        <include refid="Base_Column_List"/>
        from tree_table
        where parent_code=#[code]
    </select>
    <select id="noteTree" resultMap="NodeTreeResult">
        select
        <include refid="Base_Column_List"/>
        from tree_table
        where parent_code='0'
    </select>
</mapper>

noteTree ：获取所有父级节点数据；
nextNoteTree：循环获取子节点数据，知道叶子节点结束；
column：关联表的列名；
ofType：返回类型

启动类


@Slf4j
@Component
public class TreeTableCommandLineRunner implements CommandLineRunner {
    @Resource
    private TreeTableMapper treeTableMapper;

    @Override
    public void run(String... args) throws Exception {
        log.info(JSONUtil.tojsonPrettyStr(treeTableMapper.noteTree()));
    }
}

最终效果


[
    {
        "code": "10000",
        "childNode": [
            {
                "code": "10001",
                "childNode": [
                    {
                        "code": "1000101",
                        "childNode": [
                        ],
                        "parentCode": "10001",
                        "name": "联想拯救者",
                        "id": 5
                    },
                    {
                        "code": "1000102",
                        "childNode": [
                        ],
                        "parentCode": "10001",
                        "name": "联想小新系列",
                        "id": 6
                    }
                ],
                "parentCode": "10000",
                "name": "联想笔记本",
                "id": 3
            },
            {
                "code": "10002",
                "childNode": [
                ],
                "parentCode": "10000",
                "name": "惠普笔记本",
                "id": 4
            }
        ],
        "parentCode": "0",
        "name": "电脑",
        "id": 1
    }
]

注意事项

使用mybatis时如加载不到mapper xml需在pom.xml添加以下配置：


<resources>
    <resource>
        <directory>src/main/resources</directory>
        <filtering>true</filtering>
    </resource>
    <resource>
        <directory>src/main/java</directory>
        <includes>
            <include>**/*.xml</include>
        </includes>
    </resource>
</resources>