SpringBoot整合Mybatis (四) 多对多

SpringBoot整合Mybatis

四、多对多实现

    目标：根据id查询用户选择的运营商

1. 构建项目

    使用上一章内容

2. 创建数据库

1). user表：

CREATE TABLE user(
	id INT(10) NOT NULL AUTO_INCREMENT COMMENT '编号',
	name VARCHAR(50) NOT NULL COMMENT '用户名',
	PRIMARY KEY(id)
)ENGINE=INNODB AUTO_INCREMENT=0 DEFAULT CHARSET=utf8;

2). combo表：

CREATE TABLE combo(
	id INT(10) NOT NULL AUTO_INCREMENT COMMENT '编号',
	name VARCHAR(50) NOT NULL COMMENT '运营商名称',
	PRIMARY KEY(id)
)ENGINE=INNODB AUTO_INCREMENT=0 DEFAULT CHARSET=utf8;

3). user_combo表：

CREATE TABLE user_combo(
	uid INT(10) NULL COMMENT '用户编号',
	cid INT(10) NULL COMMENT '运营商编号',
	price INT(10) NULL COMMENT '价格'
)ENGINE=INNODB AUTO_INCREMENT=0 DEFAULT CHARSET=utf8;

3. 编写代码

1). 实体类Combo

    位于entity包

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

    private int id;
    private String name;

    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

/**
 * @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<Combo> combos;

    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). 实体类User

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

/**
 * @author Ray
 * @date 2018/7/7 0007
 * 用户实体类
 */
public class User {

    /**
     * 编号（主键）
     */
    private int id;

    /**
     * 用户名
     */
    private String name;

    /**
     * 新增Phone集合
     */
    private List<Phone> phones;

    /**
     * 新增UserCombo集合
     */
    private List<UserCombo> userCombos;

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

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

    public List<Phone> getPhones() {
        return phones;
    }

    public void setPhones(List<Phone> phones) {
        this.phones = phones;
    }

    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;
    }

    public User() {
    }

    public User(String name) {
        this.name = name;
    }

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

4). 数据操作类UserMapper

    位于mapper包，添加查询方法selectComboById(Integer id)

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

    /**
     * 根据id获取用户信息
     */
    public User selectById(Integer id);

    /**
     * 查询所有用户信息
     */
    public List<User> list();

    /**
     * 新增用户信息
     */
    public int insert(User user);

    /**
     * 修改用户信息
     */
    public int update(User user);

    /**
     * 删除用户信息
     */
    public int delete(Integer id);

    /**
     * 根据id查询用户的所有电话信息
     */
    public User selectPhoneById(Integer id);

    /**
     * 根据id查询用户选择的运营商
     */
    public User selectComboById(Integer id);
}

5). UserMapper类映射UserMapper.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.ray.mybatis.mapper.UserMapper">

    <!-- 新增用户信息 -->
    <insert id="insert" parameterType="user">
        INSERT INTO
        user(name)
        VALUES
        (#{name})
    </insert>

    <!-- 修改用户信息 -->
    <update id="update" parameterType="user">
        UPDATE
        user
        SET
        name=#{name}
        WHERE
        id=#{id}
    </update>

    <!-- 删除用户信息 -->
    <delete id="delete">
        DELETE
        FROM
        user
        WHERE
        id=#{id}
    </delete>

    <!-- 根据id获取用户信息 -->
    <select id="selectById" resultType="user" parameterType="int">
        SELECT
        *
        FROM
        user
        WHERE
        id=#{id}
    </select>

    <!-- 查询所有用户信息 -->
    <select id="list" resultType="user">
        SELECT
        *
        FROM
        user
    </select>

    <!-- 注意：当多个表的字段名一样的时候，查询需要用别名，否则查询结果不理想 -->
    <resultMap id="phoneMap" type="user">
        <id property="id" column="id"/>
        <result property="name" column="name"/>
        <!-- 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"/>
            <result property="uid" column="uid"/>
        </collection>
    </resultMap>
    <!-- 根据id查询用户的所有电话信息 -->
    <select id="selectPhoneById" resultMap="phoneMap" parameterType="int">
    SELECT
    u.*,
    p.id pid,p.name pname,p.number,p.uid
    FROM
    user u, phone p
    WHERE
    u.id=p.uid
    and
    u.id=#{id}
    </select>

    <!-- 注意：抽离userMap -->
    <resultMap id="userMap" type="user">
        <id property="id" column="id"/>
        <result property="name" column="name"/>
    </resultMap>

    <!-- 注意：继承userMap -->
    <resultMap id="comboMap" type="user" extends="userMap">
        <!-- 一对多 -->
        <collection property="userCombos" ofType="userCombo">
            <result property="price" column="price"/>
            <result property="uid" column="uid"/>
            <result property="cid" column="cid"/>
            <!-- 一对多 -->
            <collection property="combos" ofType="combo">
                <id property="id" column="cid"/>
                <result property="name" column="cname"/>
            </collection>
        </collection>
    </resultMap>

    <!-- 根据id查询用户选择的运营商 -->
    <select id="selectComboById" parameterType="int" resultMap="comboMap">
    SELECT
    u.*,
    b.price,b.uid,b.cid,
    c.id cid,c.name cname
    FROM
    user u,user_combo b,combo c
    WHERE
    u.id=b.uid
    AND
    b.cid=c.id
    AND
    u.id=#{id}
    </select>
</mapper>

6). 数据控制类UserController

    位于controller包

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

    @Autowired
    private UserMapper userMapper;

    /**
     * 根据id获取用户信息
     * localhost:8080/user/2
     */
    @GetMapping("/user/{id}")
    public User selectById(@PathVariable("id")Integer id){
        User user = userMapper.selectById(id);
        return user;
    }

    /**
     * 查询所有用户信息
     * localhost:8080/users
     */
    @GetMapping("/users")
    public List<User> list(){
        List<User> users = userMapper.list();
        return users;
    }

    /**
     * 新增用户信息
     * localhost:8080/user?name=Ray1
     */
    @PostMapping("/user")
    public String insert(User user){
        int result = userMapper.insert(user);
        if(result == 1){
            return "success";
        }
        return "fail";
    }

    /**
     * 修改用户信息
     * localhost:8080/user/2?name=Ray22
     */
    @PutMapping("/user/{id}")
    public String update(User user, @PathVariable("id") Integer id){
        int result = userMapper.update(user);
        if(result == 1){
            return "success";
        }
        return "fail";
    }

    /**
     * 删除用户信息
     * localhost:8080/user/8
     */
    @DeleteMapping("/user/{id}")
    public String delete(@PathVariable("id") Integer id){
        int result = userMapper.delete(id);
        if(result == 1){
            return "success";
        }
        return "fail";
    }

    /**
     * 根据id查询用户的所有电话信息(一对多)
     * localhost:8080/user/phone/1
     */
    @GetMapping("/user/phone/{id}")
    public User selectPhoneById(@PathVariable("id") Integer id){
        User user = userMapper.selectPhoneById(id);
        return user;
    }

    /**
     * 根据id查询用户选择的运营商（多对多）
     * localhost:8080/user/combo/1
     */
    @GetMapping("/user/combo/{id}")
    public User selectComboById(@PathVariable("id") Integer id){
        User user = userMapper.selectComboById(id);
        return user;
    }
}

4. 测试

    根据id查询用户选择的运营商-GET