目录
层级结构
java层中、resources层 及 test测试建议层级结构相同
这样生成的target看起来一目了然!
Mapper接口
IdCardMapper
public interface IdCardMapper {
Idcard findIdcardById(int id);
}OrderMapper
public interface OrderMapper {
List<Order> findOrdersByUserId(int id);
Order findOrderById(int id);
Order findOrderById2(int id);
}ProductMapper
public interface ProductMapper {
Product findProductbyId(int pdId);
}UsersMapper
public interface UsersMapper {
Users findUsersById(int id);
Users findUsersById2(int id);
Users findUserOrder(int id);
Users findUserOrder1(int id);
}pojo实体类
// 这里因为引入了lombok依赖，所以为了简便直接写的Data注释（不建议）
IdCard
@Data
public class Idcard {
private Integer id;
private String code;
}Order
@Data
public class Order {
int or_id;
String order_num ;
int user_id;
List<Product> productList;
}Product
@Data
public class Product {
int pd_id;
String book_name;
double price;
List<Order> orderList;
}@Data
public class Users {
int uid ;
String uname;
int uage;
String usex;
Idcard uidcard;
List<Order> orderList;
}工具类：
MybatisUtil
public class MybatisUtil {
private static SqlSessionFactory sqlSessionFactory = null;
static {
Reader resourceAsReader = null;
try {
resourceAsReader = Resources.getResourceAsReader("mybatis-config.xml");
} catch (IOException e) {
e.printStackTrace();
}
sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsReader);
}
public static SqlSession geSqlSession(){
// 直接提交事务
return sqlSessionFactory.openSession(true);
}
}映射文件***Mapper.xml
IdCardMapper
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!-- 修改为IdCard的映射文件路径-->
<mapper namespace="com.gcx.Mapper.IdCardMapper">
<select id="findIdcardById" resultType="com.gcx.pojo.Idcard">
select * from mybatis.tb_idcard where id = #{id}
</select>
</mapper>OrderMapper
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!-- 修改为Order的映射文件路径-->
<mapper namespace="com.gcx.Mapper.OrderMapper">
<select id="findOrdersByUserId" resultType="com.gcx.pojo.Order">
select *
from mybatis.tb_orders
where user_id = #{id}
</select>
<!-- map-->
<select id="findOrderById" resultMap="FindOrderByIdMap">
select *
from mybatis.tb_orders
where user_id = #{id}
</select>
<resultMap id="FindOrderByIdMap" type="com.gcx.pojo.Order">
<id property="or_id" column="or_id"/>
<result property="order_num" column="order_num"/>
<collection property="productList" column="or_id" select="com.yiwu.mapper.ProductMapper.findProductbyId"/>
</resultMap>
<select id="findOrderById2" resultMap="findOrderById2Map">
select o.*, p.*
from mybatis.tb_orders o,
mybatis.tb_product p,
mybatis.tb_ordersitem op
where o.or_id = #{id}
and op.or_id = o.or_id
and op.pd_id = p.pd_id
</select>
<resultMap id="findOrderById2Map" type="com.gcx.pojo.Order">
<id property="or_id" column="or_id"/>
<result property="order_num" column="order_num"/>
<!-- 返回集合-->
<collection property="productList" ofType="com.gcx.pojo.Product">
<id property="pd_id" column="pd_id"/>
<result property="book_name" column="book_name"/>
<result property="price" column="price"/>
</collection>
</resultMap>
</mapper>ProductMapper
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!-- 修改为Product的映射文件路径-->
<mapper namespace="com.gcx.Mapper.ProductMapper">
<select id="findProductbyId" resultType="com.gcx.pojo.Product">
<!--查找并根据tb_ordersitem表中的pd_id查找对应的tb_product中的pd_id所有-->
select* from mybatis.tb_product where pd_id in (select pd_id from mybatis.tb_ordersitem where or_id = #{or_id})
</select>
</mapper>UsersMapper
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!-- 修改映射文件路径-->
<mapper namespace="com.gcx.Mapper.UsersMapper">
<select id="findUsersById" resultMap="findIdCardByIDMapper">
select * from mybatis.tb_user where uid = #{uid}
</select>
<resultMap id="findIdCardByIDMapper" type="com.gcx.pojo.Users">
<association property="uidcard" column="ucard_id" select="com.gcx.mapper.IdCardMapper.findIdcardById"/>
</resultMap>
<select id="findUsersById2" resultMap="findIdCardByIDMapper2">
select u.*,card.id as cardID,card.code as ucard from mybatis.tb_user u,mybatis.tb_idcard card where u.uid = #{uid} and u.ucard_id = card.id
</select>
<resultMap id="findIdCardByIDMapper2" type="com.gcx.pojo.Users">
<id property="uid" column="uid"/>
<result property="uname" column="uanme"/>
<result property="uage" column="uage"/>
<result property="usex" column="usex"/>
<association property="uidcard" javaType="com.gcx.pojo.Idcard">
<id property="id" column="cardID"/>
<result property="code" column="ucard"/>
</association>
</resultMap>
<select id="findUserOrder" resultMap="findUserOrderMapper">
select *
from mybatis.tb_user
where uid = #{uid};
</select>
<resultMap id="findUserOrderMapper" type="com.gcx.pojo.Users">
<id property="uid" column="uid"/>
<result property="uname" column="uanme"/>
<result property="uage" column="uage"/>
<result property="usex" column="usex"/>
<collection property="orderList" column="uid" select="com.yiwu.mapper.OrderMapper.findOrdersByUserId"/>
</resultMap>
<select id="findUserOrder1" resultMap="findUserOrderMapper2">
select u.*,o.*
from mybatis.tb_user u,mybatis.tb_orders o
where u.uid = #{id} and o.user_id = u.uid
</select>
<resultMap id="findUserOrderMapper2" type="com.gcx.pojo.Users">
<id property="uid" column="uid"/>
<result property="uname" column="uanme"/>
<result property="uage" column="uage"/>
<result property="usex" column="usex"/>
<collection property="orderList" ofType="com.gcx.pojo.Order">
<id property="or_id" column="or_id"/>
<result property="order_num" column="order_num"/>
</collection>
</resultMap>
</mapper>Test测试
public class UserTest {
// 定义全局变量
private UsersMapper mapper;
private SqlSession sqlSession;
private OrderMapper mappers;
@Before
public void before(){
sqlSession = MybatisUtil.geSqlSession();
mapper = sqlSession.getMapper(UsersMapper.class);
}
@Test
public void test01(){
Users users = mapper.findUsersById2(1);
System.out.println(users);
}
@Test
public void test02(){
Users users = mapper.findUserOrder1(1);
System.out.println(users);
}
@Test
public void test03(){
mappers = sqlSession.getMapper(OrderMapper.class);
Order order = mappers.findOrderById2(2);
System.out.println(order);
}
@After
public void after(){
sqlSession.close();
}
}mybatis-config.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<!-- 环境配置 -->
<!-- 加载类路径下的属性文件 -->
<properties resource="db.properties"/>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<!-- 数据库连接相关配置 ,db.properties文件中的内容-->
<dataSource type="POOLED">
<property name="driver" value="${mysql.driver}"/>
<property name="url" value="${mysql.url}"/>
<property name="username" value="${mysql.username}"/>
<property name="password" value="${mysql.password}"/>
</dataSource>
</environment>
</environments>
<!-- mapping文件路径配置 -->
<mappers>
<!-- 全局包扫描-->
<package name="com.gcx.Mapper"/>
</mappers>
</configuration>数据库文件
use mybatis;
# 创建一个编码表
CREATE TABLE tb_idcard(
id INT PRIMARY KEY AUTO_INCREMENT,
CODE VARCHAR(18)
);
INSERT INTO tb_idcard(CODE) VALUES('111111111111111');
INSERT INTO tb_idcard(CODE) VALUES('22222222222222');
INSERT INTO tb_idcard(CODE) VALUES('33333333333333');
# 创建一个用户表
create table tb_user(
uid INT PRIMARY KEY AUTO_INCREMENT,
uname VARCHAR(32),
uage INT,
usex VARCHAR(8),
ucard_id INT UNIQUE,
FOREIGN KEY(ucard_id) REFERENCES tb_idcard(id)
);
insert into tb_user(uname,uage,usex,ucard_id) values('张三',20,'男',2);
insert into tb_user(uname,uage,usex,ucard_id) values('李四',18,'男',3);
insert into tb_user(uname,uage,usex,ucard_id) values('王五',22,'女',1);
# 创建一个订单表表
CREATE TABLE tb_orders (
or_id int(32) PRIMARY KEY AUTO_INCREMENT,
order_num varchar(32) NOT NULL,
user_id int(32) NOT NULL,
FOREIGN KEY(user_id) REFERENCES tb_user(uid)
);
INSERT INTO tb_orders(order_num,user_id) VALUES('20211111',1);
INSERT INTO tb_orders(order_num,user_id) VALUES('202222222',1);
INSERT INTO tb_orders(order_num,user_id) VALUES('202233333',2);
INSERT INTO tb_orders(order_num,user_id) VALUES('2022444444',3);
#创建一个商品表
CREATE TABLE tb_product (
pd_id INT(32) PRIMARY KEY AUTO_INCREMENT,
book_name VARCHAR(32),
price DOUBLE
);
INSERT INTO tb_product(book_name,price) VALUES ('Java基础', '20');
INSERT INTO tb_product(book_name,price) VALUES ('前端技术', '30');
INSERT INTO tb_product(book_name,price) VALUES ('SSM框架', '4');
# 创建一个中间表
CREATE TABLE tb_ordersitem (
id INT(32) PRIMARY KEY AUTO_INCREMENT,
or_id INT(32),
pd_id INT(32),
FOREIGN KEY(or_id) REFERENCES tb_orders(or_id),
FOREIGN KEY(pd_id) REFERENCES tb_product(pd_id)
);
INSERT INTO tb_ordersitem(or_id,pd_id) VALUES ('1', '1');
INSERT INTO tb_ordersitem(or_id,pd_id) VALUES ('1', '3');
INSERT INTO tb_ordersitem(or_id,pd_id) VALUES ('2', '2');
INSERT INTO tb_ordersitem(or_id,pd_id) VALUES ('3', '1');
INSERT INTO tb_ordersitem(or_id,pd_id) VALUES ('3', '2');
INSERT INTO tb_ordersitem(or_id,pd_id) VALUES ('3', '3');