最近開始嘗試hibernate annotations，終于成功的將手上一個小應用轉為annotations ：）
1、spring orm support與原來使用LocalSessionFactoryBean相比，變動不大（AnnotationSessionFactoryBean本來就是從LocalSessionFactoryBean類繼承過來的嘛）
?1????<bean
?2?????????id="sessionFactory"
?3?????????class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean"
?4?????????parent="AbstractSessionFactory">
?5?????????<property?name="annotatedClasses">
?6?????????????<list>
?7?????????????????<value>xxx.xxx.xxx.domain.Account</value>
?8?????????????</list>
?9?????????</property>
10?????</bean>
11?????<bean
12?????????id="AbstractSessionFactory"
13?????????class="org.springframework.orm.hibernate3.LocalSessionFactoryBean"
14?????????abstract="true">
15?????????<property
16?????????????name="dataSource"
17?????????????ref="DataSource"?/>
18?????????<property?name="hibernateProperties">
19?????????????<props>
20?????????????????<prop?key="hibernate.dialect">${hibernate.dialect}</prop>
21?????????????????<prop?key="hibernate.show_sql">${hibernate.show_sql}</prop>
22?????????????????<prop?key="hibernate.hbm2ddl.auto">${hibernate.hbm2ddl.auto}</prop>
23?????????????????<prop?key="hibernate.cache.use_query_cache">${hibernate.cache.use_query_cache}</prop>
24?????????????????<prop?key="hibernate.cache.provider_class">${hibernate.cache.provider_class}</prop>
25?????????????</props>
26?????????</property>
27?????????<property
28?????????????name="lobHandler"
29?????????????ref="DefaultLobHandler"?/>
30?????</bean>
2、id的配置非常簡單，在id的getter上面加個“@Id”就可以了。此時采用的id策略是javax.persistence.GenerationType.AUTO，也可以再加上“@GeneratedValue(generator =GenerationType.IDENTITY|GenerationType.SEQUENCE|GenerationType.TABLE)”換成其它策略。
我的應用采用的是hibernate的uuid策略，就不得不在這兒使用hibernate的擴展了
??@Id
??@Column(length?=?32)
??@GeneratedValue(generator?=?"system-uuid")
??@GenericGenerator(name?=?"system-uuid",?strategy?=?"uuid")
3、級聯策略在ejb3-persistence.jar中只定義了ALL、MERGE、PERSIST、REFRESH、REMOVE，比較惡心的就是，刪除對象的時候，并不會級聯刪除關聯對象，而是用update xx set parent_id=null where parent_id=?這類語句把關系干掉了事。不得已，在這兒用了hibernate的DELETE_ORPHAN。
??@OneToMany(targetEntity?=?Attachment.class)
??@Cascade(value?=?{org.hibernate.annotations.CascadeType.DELETE_ORPHAN,
??????org.hibernate.annotations.CascadeType.ALL})
??@JoinColumn(name?=?"info_id")
4、CACHEejb3-persistence.jar里面沒有找到cache的配置，繼續請出hibernate來干活
import?org.hibernate.annotations.Cache;
import?org.hibernate.annotations.CacheConcurrencyStrategy;
@Entity
@Table(name?=?"T_INFO")
@Cache(usage?=?CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)
5、自定義字段類型我的POJO中有一個private String content;的屬性，按ejb3配成@Lob后，被處理成了text類型，text 64k的存儲容量還是比較可憐了。
??@Lob
??@Column(columnDefinition?=?"LongText")