Hibernate4之多对多双向关联

在这里多对多关系@ManyToMany，默认是延迟加载的。

/**
 * @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;
	}
	
}

评论

3 楼 spp_1987 2013-09-06  

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory' defined in class path resource [spring-context.xml]: Invocation of init method failed; nested exception is org.hibernate.MappingException: Could not determine type for: java.util.Set, at table: T_RoleTree, for columns: [org.hibernate.mapping.Column(users)]

启动项目的时候　报　T_RoleTree没有这个 users字段啊？ users不只是在T_RoleTree的Set

2 楼 spp_1987 2013-09-06  

后台保存订单下面  有很多订单 调了 对应什么方法 实现的？

1 楼 spp_1987 2013-09-06  

订单 和 商品之间 有中间表存在吗？？？