Mybatis+Mysql 实现树形结构查询

Mybatis <collection 实现树形结构>该实现使用的是SpringBoot 其实用Spring也是差不多的只要知道Mapper怎么写就可以

直接贴代码：
1.MySql创建数据库表
CREATE TABLE `node` (
`id` int(11) unsigned NOT NULL AUTO_INCREMENT,
`name` varchar(32) NOT NULL,
`parent_id` int(11) unsigned NOT NULL,
PRIMARY KEY (`id`),
KEY `parent_id` (`parent_id`)
) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8mb4 COMMENT='节点表'
简单的节点父子关系设计，下面插入几条数据：

INSERT INTO node (name, parent_id) VALUES ('一级节点A', 0);
INSERT INTO node (name, parent_id) VALUES ('一级节点B', 0);
INSERT INTO node (name, parent_id) VALUES ('一级节点C', 0);
INSERT INTO node (name, parent_id) VALUES ('二级节点AA', 1);
INSERT INTO node (name, parent_id) VALUES ('二级节点aa', 1);
INSERT INTO node (name, parent_id) VALUES ('二级节点BB', 2);
INSERT INTO node (name, parent_id) VALUES ('三级级节点AAA', 4);
INSERT INTO node (name, parent_id) VALUES ('三级级节点aaa', 4);
INSERT INTO node (name, parent_id) VALUES ('三级级节点BBB', 6);

2.Bean：
/**
* 节点实体类
*
* Created by bysocket on 24/01/2018.
*/
public class Node {

/**
* 编号
*/
private Long id;

/**
* 名称
*/
private String name;

/**
* 下一个节点
*/
private List<Node> next;

public Long getId() {
return id;
}

public void setId(Long id) {
this.id = id;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public List<Node> getNext() {
return next;
}

public void setNext(List<Node> next) {
this.next = next;
}
}

3.service:
/**
* 节点业务逻辑接口类
*
* Created by bysocket on 24/01/2018.
*/
public interface NodeService {

/**
* 获取节点树
*/
List<Node> getNodeTree();
}

4.service实现类：
/**
* 节点业务逻辑实现类
*
* Created by bysocket on 24/01/2018.
*/
@Service
public class CityServiceImpl implements NodeService {

@Autowired
private NodeDao nodeDao;

@Override
public List<Node> getNodeTree() {
return nodeDao.getNodeTree();
}
}

5.Dao层：
/**
* 节点 DAO 接口类
*
* Created by bysocket on 24/01/2018.
*/
public interface NodeDao {

/**
* 获取节点树
*/
List<Node> getNodeTree();
}

6.Mapper：
<?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="org.mybatis.dao.NodeDao">
<resultMap id="BaseTreeResultMap" type="org.mybatis.domain.Node">
<result column="id" property="id"/>
<result column="name" property="name"/>
<collection column="id" property="next" javaType="java.util.ArrayList"
ofType="org.mybatis.domain.Node" select="getNextNodeTree"/>
</resultMap>

<resultMap id="NextTreeResultMap" type="org.mybatis.domain.Node">
<result column="id" property="id"/>
<result column="name" property="name"/>
<collection column="id" property="next" javaType="java.util.ArrayList"
ofType="org.mybatis.domain.Node" select="getNextNodeTree"/>
</resultMap>

<sql id="Base_Column_List">
id, name
</sql>

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

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

</mapper>

7.controller：

/**
* 节点业务控制成类
*
* Created by bysocket on 24/01/2018.
*/
@RestController
public class NodeRestController {

@Autowired
private NodeService nodeService;

@GetMapping(value = "/node/tree")
public List<Node> getNodeTree() {
return nodeService.getNodeTree();
}

//附加一个递归的获取树节点

    public List<Node> getTree(){
//        int i = 0;
        List<Node> list = nodeService.getNodeTree();
//        首次循环获取母节点
        for(Node node: list){
            System.out.println("start"+node.getName());
            getList(node.getNext());
        }

        return list;
    }
    public void getList(List<Node> list){

        Node nd = new Node();
        if(list != null){
            if(list.size()>0){
                for(Node node : list){
//                    i++;
                    System.out.println(node.getName());
                    nd.setId(node.getId());
                    nd.setName(node.getName());
                    //递归获取下一个子节点
                    getList(node.getNext());
                }
            } else{
//                i = 0;
//                System.out.println("枝干结束"+i);
            }
        } else{
//            i = 0;
        }
    }

}

试起来吧！
文本摘自：https://www.bysocket.com/?p=2008
工程代码：https://github.com/JeffLi1993/myabtis-learning-example

Mybatis+Mysql 实现树形结构查询

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