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Hibernate4之多对一单向关联

2015-11-25 00:00 393 查看
一个客户可以有多个订单,订单对应一个客户的关系就是多对一。
在这里多对一的关系是@ManyToOne,默认是非延迟加载的。如果要设置懒加载必须设置fetch = FetchType.LAZY,但是既然配置了多对一,肯定是希望加载订单的时候加载出客户信息的。

/**
* @author Chou
* @since 2012-8-8
* ...客户实体
*
*/

@Entity
@Table(name = "TAB_CUSTOMER")
@SequenceGenerator(name = "seq", sequenceName = "SEQ_CUSTOMER", allocationSize = 1)
public class Customer {
private Long id;
private String cname;
private String address;
private String phone;

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

public void setId(Long id) {
this.id = id;
}

......

}


/**
* @author Chou
* @since 2012-8-8
* ...订单实体(多对一关系维护方)
*
*/

@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 Customer customer;

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

.....

@ManyToOne
@Cascade(value = { org.hibernate.annotations.CascadeType.SAVE_UPDATE })
@JoinColumn(name = "CUSTOMERID")
public Customer getCustomer() {
return customer;
}
public void setCustomer(Customer customer) {
this.customer = customer;
}
}
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