MyBatis注解之多对多

1、ProductMapper

public interface ProductMapper {@Select("select * from product_ where id = #{id}")public Product get(int id);
}

2、OrderItemMapper
提供listByOrder方法，与Product建立多对一关系。

public interface OrderItemMapper {@Select(" select * from order_item_ where oid = #{oid}")@Results({ @Result(property="product",column="pid",one=@One(select="com.how2java.mapper.ProductMapper.get")) }) public List<OrderItem> listByOrder(int oid);
}

3、OrderMapper
提供list方法，与OrderItem建立一对多关系。

public interface OrderMapper {@Select("select * from order_")@Results({@Result(property = "id", column = "id"),@Result(property = "orderItems", javaType = List.class, column = "id", many = @Many(select = "com.how2java.mapper.OrderItemMapper.listByOrder"))})      public List<Order> list();
}

4、mybatis-config.xml

        <mapper class="com.how2java.mapper.OrderItemMapper"/><mapper class="com.how2java.mapper.OrderMapper"/><mapper class="com.how2java.mapper.ProductMapper"/>

5、Test类

public class TestMybatis {public static void main(String[] args) throws IOException {String resource = "mybatis-config.xml";InputStream inputStream = Resources.getResourceAsStream(resource);SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);SqlSession session = sqlSessionFactory.openSession();listOrder(session);session.commit();session.close();}private static void listOrder(SqlSession session) {OrderMapper mapper =session.getMapper(OrderMapper.class);List<Order> os = mapper.list();for (Order o : os) {System.out.println(o.getCode());List<OrderItem> ois= o.getOrderItems();if(null!=ois){for (OrderItem oi : ois) {System.out.format("\t%s\t%f\t%d%n", oi.getProduct().getName(),oi.getProduct().getPrice(),oi.getNumber());}              }}}
}