mybatis一对多

mapper.xml

<mapper namespace="com.oracle.dao.one2manyDao">

    <resultMap type="com.oracle.pojo.Order" id="orderResuleMap">
        <id column="orderId" property="id"/>
        <result column="ordered_date" property="ordered_date"/>
        <result column="shipped_date" property="shipped_date"/>
        <result column="total" property="total"/>
        <collection property="orderlines" ofType="com.oracle.pojo.OrderLine" javaType="java.util.HashSet" column="order_id">
            <id column="id" property="id"/>
            <result column="price" property="price"/>
            <result column="quantity" property="quantity"/>
            <result column="product" property="product"/>
        </collection>
    </resultMap>

    <select id="getOrderAndOrderLines" resultMap="orderResuleMap" parameterType="java.lang.Long">
        select o.id as orderId,o.ordered_date,o.shipped_date,o.total,
        ol.id,ol.price,ol.quantity, ol.product
        from t_order o left join t_orderline ol
        on o.id=ol.order_id
        where o.id=#{id}
        
    </select>
    
</mapper>

//实体类
public class OrderLine implements Serializable {
    private long id;
    private double price;
    private long quantity;
    private String product;
    private Order order;


public class Order implements Serializable {
    private Long id;
    private Date ordered_date;
    private Date shipped_date;
    private Long total;
    private Set<OrderLine> orderlines = new HashSet<OrderLine>();