Hibernate的cascade总结
1.JPA中的CascadeType.ALL并不等于{CascadeType.PESIST,CascadeType.REMOVE,CascadeType.MERGE,CascadeType.REFRESH}
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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)
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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")})
@Entitypublic 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;}}@Entitypublic 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(value=@CascadeType.DELETE_ORPHAN)来达到此目的