Hibernate的cascade总结

1.JPA中的CascadeType.ALL并不等于{CascadeType.PESIST,CascadeType.REMOVE,CascadeType.MERGE,CascadeType.REFRESH}

在Hibernate中调用session.save() or session.update()并不能触发{CascadeType.PESIST,CascadeType.REMOVE,CascadeType.MERGE,CascadeType.REFRESH}的级联操作，而能触发CascadeType.ALL的级联。如不希望用CascadeType.ALL，需要使用Hibernate自身对cascade的注解@Cascade(value=org.hibernate.annotations.CascadeType.SAVE_UPDATE)

2.共享主键的OneToOne方式不能通过cascade来自动生成标识符，即使声明了@GenericGenerator(name="foreign_key",strategy="foreign",parameters={@Parameter(name="property",value="person")})

@Entity
public class Person implements Serializable {
        @Id
	@GeneratedValue(generator = "g_id")
	public String getId() {
		return id;
	}
	
         @OneToOne(cascade = { CascadeType.PERSIST ,CascadeType.ALL})
         @JoinColumn(name = "profile_id")
	 @PrimaryKeyJoinColumn(name="id")
	public Profile getProfile() {
		return profile;
	}
}

@Entity
public class Profile implements Serializable {

        @Id
	@GenericGenerator(name = "foreign_key", strategy = "foreign", parameters = { @Parameter(name = "property", value = "person") })
	@GeneratedValue(generator = "foreign_key")
	public String getId() {
		return id;
	}

        @OneToOne(mappedBy = "profile")
	public Person getPerson() {
		return person;
	}

	public void setPerson(Person person) {
		this.person = person;
	}
}

3.delete-orphan只应用在OneToMany中，能级联删除Many集合中的子元素。

   NOTE:JPA并不支持delete-orphan，但并不明白hibernate reference中为什么可以在OneToMany中添加属性orphanRemoval=true的属性。事实上，要用hibernate独有的注解@Cascade([email protected]_ORPHAN)来达到此目的