Hibernate4之多对多双向关联

最新推荐文章于 2025-07-28 23:27:29 发布

原创最新推荐文章于 2025-07-28 23:27:29 发布 · 81 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#hibernate #多对多双向关联 #JPA

Hibernate 专栏收录该内容

22 篇文章

订阅专栏

本文详细介绍了如何在Java实体类中使用@ManyToMany注解实现多对多关系，包括实体类的设计、关系维护方以及关联表的使用。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

[size=medium]在这里多对多关系@ManyToMany，默认是延迟加载的。[/size]


/**
 * @author Chou
 * @since 2012-8-8
 * ...订单实体（多对多关系维护方）
 *
 */

@Entity
@Table(name = "TAB_ORDER")
@SequenceGenerator(name = "seq", sequenceName = "SEQ_ORDER", allocationSize = 1)
public class Order {
	private Long id;
	private String orderno;
	private Double money;
	private Set<Item> items = new HashSet<Item>();

	@Id
	@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "seq")
	public Long getId() {
		return id;
	}

	......

	@ManyToMany(fetch = FetchType.EAGER)
	@JoinTable(
		name = "TAB_ORDER_ITEM",
		joinColumns = {@JoinColumn(name = "ORDERID", nullable = false) },
		inverseJoinColumns = {@JoinColumn(name = "ITEMID", nullable = false)}
	)
	public Set<Item> getItems() {
		return items;
	}

	public void setItems(Set<Item> items) {
		this.items = items;
	}
}


/**
 * @author Chou
 * @since 2012-8-8
 * ...商品实体（多对多关联）
 *
 */

@Entity
@Table(name = "TAB_ITEM")
@SequenceGenerator(name = "seq", sequenceName = "SEQ_ITEM", allocationSize = 1)
public class Item {
	private Long id;
	private String itemNo;
	private String itemName;
	private Set<Order> orders = new HashSet<Order>();

	@Id
	@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "seq")
	public Long getId() {
		return id;
	}

	......

	@ManyToMany(mappedBy = "items", fetch = FetchType.EAGER)
	public Set<Order> getOrders() {
		return orders;
	}

	public void setOrders(Set<Order> orders) {
		this.orders = orders;
	}

}