本实例使用顾客和订单的例子做说明: 一个顾客可以有多个订单, 一个订单只对应一个顾客
二. 例子:
1. 代码结构图:
2. 建表语句:
1. CREATE DATABASE test;
2.
3. USE test;
4.
5. CREATE TABLE person(
6. VARCHAR(36) PRIMARY KEY,
7. VARCHAR(64),
8. VARCHAR(128),
9. VARCHAR(11)
10. );
11.
12. CREATE TABLE orders(
13. VARCHAR(36) PRIMARY KEY,
14. VARCHAR(20),
15. INT,
16. VARCHAR(36)
17. );
18.
19. INSERT INTO person VALUES('001', 'Jack', 'Wuhan', '1234567');
20. INSERT INTO orders VALUES('O_00001', '00001', 100, '001');
21. INSERT INTO orders VALUES('O_00002', '00002', 200, '001');
22.
23. SELECT p.*, o.*
24. FROM person p
25. JOIN orders o ON (p.personId=o.pid)
26. WHERE p.personId = '001'
3. 顾客实体:
1. /**
2. * 客户实体
3. */
4. public class Person {
5.
6. private String id;
7. private String name;
8. private String address;
9. private String tel;
10.
11. private List<Order> orders;
12.
13. @Override
14. public String toString() {
15. return "{id: " + id + ", name: " + name + ", address: " + address + ", tel: " + tel + "}";
16. }
17. }
4. 订单实体:
1. /**
2. * 订单实体
3. */
4. public class Order {
5.
6. private String id;
7. private String number;
8. private int price;
9.
10. private Person person;
11.
12. @Override
13. public String toString() {
14. return "{id: " + id + ", number: " + number + ", price: " + price + "}";
15. }
16.
17. }
5. 一对多实体配置: Person.xml
1. <?xml version="1.0" encoding="UTF-8" ?>
2. <!DOCTYPE mapper
3. PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
4. "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
5. <mapper namespace="com.zdp.domain.Person">
6.
7. <resultMap type="Person" id="personBean">
8. <id column="personId" property="id"/>
9. <result column="personName" property="name"/>
10. <result column="personAddress" property="address"/>
11. <result column="personTel" property="tel"/>
12.
13. <!-- 一对多的关系 -->
14. <!-- property: 指的是集合属性的值, ofType：指的是集合中元素的类型 -->
15. <collection property="orders" ofType="Order">
16. <id column="orderId" property="id"/>
17. <result column="orderNumber" property="number"/>
18. <result column="orderPrice" property="price"/>
19. </collection>
20. </resultMap>
21.
22. <!-- 根据id查询Person, 关联将Orders查询出来 -->
23. <select id="selectPersonById" parameterType="string" resultMap="personBean">
24. p.personId = o.pid and p.personId = #{id}
25. </select>
26.
27. </mapper>
6. 多对一实体配置:
1. <?xml version="1.0" encoding="UTF-8" ?>
2. <!DOCTYPE mapper
3. PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
4. "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
5. <mapper namespace="com.zdp.domain.Order">
6. <resultMap type="Order" id="orderBean">
7. <id column="orderId" property="id"/>
8. <result column="orderNumber" property="number"/>
9. <result column="orderPrice" property="price"/>
10.
11. <!-- 多对一的关系 -->
12. <!-- property: 指的是属性的值, javaType：指的是属性的类型-->
13. <association property="person" javaType="Person">
14. <id column="personId" property="id"/>
15. <result column="personName" property="name"/>
16. <result column="personAddress" property="address"/>
17. <result column="personTel" property="tel"/>
18. </association>
19. </resultMap>
20.
21. <!-- 根据id查询Order, 关联将Person查询出来 -->
22. <select id="selectOrderById" parameterType="string" resultMap="orderBean">
23. p.personId = o.pid and o.orderId = #{id}
24. </select>
25.
26. </mapper>
7. 总配置: sqlMapConfig.xml
1. <?xml version="1.0" encoding="UTF-8" ?>
2. <!DOCTYPE configuration
3. PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
4. "http://mybatis.org/dtd/mybatis-3-config.dtd">
5. <configuration>
6. <typeAliases>
7. <typeAlias type="com.zdp.domain.Person" alias="Person"/>
8. <typeAlias type="com.zdp.domain.Order" alias="Order"/>
9. </typeAliases>
10. <environments default="development">
11. <environment id="development">
12. <transactionManager type="JDBC" />
13. <dataSource type="POOLED">
14. <property name="driver" value="com.mysql.jdbc.Driver" />
15. <property name="url" value="jdbc:mysql://localhost/test" />
16. <property name="username" value="root" />
17. <property name="password" value="root" />
18. </dataSource>
19. </environment>
20. </environments>
21. <mappers>
22. <!-- 映射文件的位置 -->
23. <mapper resource="com/zdp/domain/Person.xml" />
24. <mapper resource="com/zdp/domain/Order.xml" />
25. </mappers>
26. </configuration>
8. 测试文件:
1. /**
2. * 测试一对多和多对一
3. */
4. public class MybatisTest {
5.
6. private SqlSessionFactory ssf;
7.
8. @Before
9. public void initSF() throws Exception {
10. "sqlMapConfig.xml";
11. InputStream inputStream = Resources.getResourceAsStream(resource);
12. new SqlSessionFactoryBuilder().build(inputStream);
13. }
14.
15. @Test//一对多关联查询
16. public void selectPersonById()throws Exception{
17. SqlSession session = ssf.openSession();
18. "com.zdp.domain.Person.selectPersonById", "001");
19. System.out.println(person.getOrders());
20. }
21.
22. @Test//多对一关联查询
23. public void selectOrderById()throws Exception{
24. SqlSession session = ssf.openSession();
25. "com.zdp.domain.Order.selectOrderById", "O_00001");
26. System.out.println(order.getPerson().getName());
27. }
28. }
