SpringBoot整合Mybatis (五) 多对多

SpringBoot整合Mybatis

五、多对多实现

    目标：根据id查询运营商拥有的用户和电话信息

1. 构建项目

    使用上一章内容

2.编写代码

1). 实体类Combo

    位于entity包，添加UserCombo集合，添加对应的setter、getter

/**
 * @author Ray
 * @date 2018/7/7 0007
 * 运营商实体类
 */
public class Combo {

    private int id;
    private String name;

    private List<UserCombo> userCombos;

    public List<UserCombo> getUserCombos() {
        return userCombos;
    }

    public void setUserCombos(List<UserCombo> userCombos) {
        this.userCombos = userCombos;
    }

    public int getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

    @Override
    public String toString() {
        return "Combo{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }
}

2). 实体类UserCombo

    位于entity包，添加User集合，添加对应的setter、getter

/**
 * @author Ray
 * @date 2018/7/7 0007
 * 用户拥有运营商实体
 */
public class UserCombo {

    private int uid;
    private int cid;
    private int price;

    private List<User> users;
    private List<Combo> combos;

    public List<User> getUsers() {
        return users;
    }

    public void setUsers(List<User> users) {
        this.users = users;
    }

    public List<Combo> getCombos() {
        return combos;
    }

    public void setCombos(List<Combo> combos) {
        this.combos = combos;
    }

    public int getUid() {
        return uid;
    }

    public void setUid(int uid) {
        this.uid = uid;
    }

    public int getCid() {
        return cid;
    }

    public void setCid(int cid) {
        this.cid = cid;
    }

    public int getPrice() {
        return price;
    }

    public void setPrice(int price) {
        this.price = price;
    }

    @Override
    public String toString() {
        return "UserCombo{" +
                "uid=" + uid +
                ", cid=" + cid +
                ", price=" + price +
                ", combos=" + combos +
                '}';
    }
}

3). 数据操作类ComboMapper

    位于mapper包，添加查询方法selectUserById

/**
 * @author Ray
 * @date 2018/7/7 0007
 * 数据操作层
 */
public interface ComboMapper {

    /**
     * 根据id查询运营商拥有的用户和电话信息
     */
    public Combo selectUserById(Integer id);
}

4). ComboMapper类映射ComboMapper.xml

      多对多的理解：就是多个一对多的组合。

<?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.ray.mybatis.mapper.ComboMapper">
    <!-- 注意：抽离comboMap -->
    <resultMap id="comboMap" type="combo">
        <id property="id" column="id"/>
        <result property="name" column="name"/>
    </resultMap>

    <!-- 注意：继承comboMap -->
    <resultMap id="userMap" type="combo" extends="comboMap">
        <!-- 一对多 【ofType是映射到list集合属性中pojo的类型】 -->
        <collection property="userCombos" ofType="userCombo">
            <result property="price" column="price"/>
            <!-- 一对多 -->
            <collection property="users" ofType="user">
                <id property="id" column="uid"/>
                <result property="name" column="uname"/>
                <!-- 一对多 【ofType是映射到list集合属性中pojo的类型】 -->
                <collection property="phones" ofType="phone">
                    <id property="id" column="pid"/>
                    <result property="name" column="pname"/>
                    <result property="number" column="number"/>
                </collection>
            </collection>
        </collection>
    </resultMap>

    <!-- 根据id查询运营商拥有的用户和电话信息 -->
    <select id="selectUserById" parameterType="int" resultMap="userMap">
    SELECT
    c.*,
    s.price,
    u.id uid,u.name uname,
    p.id pid,p.name pname,p.number
    FROM
    combo c, user_combo s, user u, phone p
    WHERE
    c.id=s.cid
    AND
    s.uid=u.id
    AND
    u.id=p.uid
    and
    c.id=#{id}
    </select>
</mapper>

5). 数据控制类ComboController

    位于controller包

/**
 * @author Ray
 * @date 2018/7/7 0007
 * 数据控制层
 */
@RestController
public class ComboController {

    @Autowired
    private ComboMapper comboMapper;

    /**
     * 根据id查询运营商拥有的用户和电话信息
     * localhost:8080/combo/user/2
     */
    @GetMapping("/combo/user/{id}")
    public Combo selectUserById(@PathVariable("id") Integer id){
        Combo combo = comboMapper.selectUserById(id);
        return combo;
    }
}

3. 测试

    根据id查询运营商拥有的客户和电话信息-GET