Hibernate注解: 联合主键:@IdClass vs @EmbeddedId
Hibernate Annotations -> 2.2.6. Mapping composite primary keys and foreign keys to composite primary keys：
http://docs.jboss.org/hibernate/annotations/3.5/reference/en/html_single/#d0e2177@Entitypublic class RegionalArticle implements Serializable { @EmbeddedId public RegionalArticlePk getPk() { ... }}public class RegionalArticlePk implements Serializable { ... }
与这段摘录呼应的一篇文章：
http://blog.csdn.net/zzh87615/article/details/6083754引用hibernate的annotation的文档中提供了三种方法
1 将组件类注解为@Embeddable,并将组件的属性注解为@Id
2 将组件的属性注解为@EmbeddedId (方便)
3 将类注解为@IdClass,并将该实体中所有属于主键的属性都注解为@Id(符合编程习惯)
主键类需要序列化(考虑到可能会将数据读写到虚拟内存中),需要重写hashcode()和equals()方法,因为要对联合主键进行比较.
Hibernate Annotation 联合主键三种写法的例子：
http://laodaobazi.iteye.com/blog/903236
Which anotation should I use: @IdClass or @EmbeddedId:
http://stackoverflow.com/questions/212350/which-anotation-should-i-use-idclass-or-embeddedid
Compound Primary Keys with Hibernate and JPA Annotations:
http://jpa.ezhibernate.com/Javacode/learn.jsp?tutorial=15usingcompoundprimarykeys
@IdClass and @EmbeddedId:
http://www.coderanch.com/t/452567/ORM/java/IdClass-EmbeddedId
遇到的一个bug：使用IdClass，居然不认@Column:
https://hibernate.onjira.com//browse/HHH-4256 1 楼 lg_asus 2011-11-11 多谢~ 半天没解决好
将类注解为@IdClass,并将该实体中所有属于主键的属性都注解为@Id(符合编程习惯)
：是将RegionalArticle 注解为@IdClass(RegionalArticlePK.class) ,然后把RegionalArticlePK中的那些属性注解为@Id吗？结果不行。
希望能解释一下~ 多谢 2 楼 lg_asus 2011-11-14 解决了， 原来主键类还要再把联合主键定义下~~~
感觉有点繁琐，但确实符合编程习惯~
