hibernate注解(annoation)使用id主键生成策略
参考原文:http://blog.csdn.net/shendeguang/article/details/47976117
hibernate注解(annoation)使用id主键生成主要要使用到以下几个注解: @Id,@GeneratedValue,@GenericGenerator. ,@GeneratedValue的作用是JPA的默认实现自定义主键生成策略,@GenericGenerator是hibernate在JPA的基础上增强。
自定义主键生成策略,由@GenericGenerator实现。hibernate在JPA的基础上进行了扩展,可以用一下方式引入hibernate独有的主键生成策略,就是通过@GenericGenerator加入的。
比如说,JPA标准用法
@Id @GeneratedValue(GenerationType.AUTO)
就可以用hibernate特有以下用法来实现
@GeneratedValue(strategy = GenerationType.AUTO) @GenericGenerator(name = "paymentableGenerator", strategy = "native")
使用@GeneratedValue
1、针对mysql,oracle,sqlserver数据库可以同时使用
@Id @GeneratedValue(strategy = GenerationType.AUTO) @GenericGenerator(name = "paymentableGenerator", strategy = "native")
name属性指定生成器名称。
strategy属性指定具体生成器的类名。
parameters得到strategy指定的具体生成器所用到的参数。
2、配合使用@GenericGenerator 不单独使用
对于这些hibernate主键生成策略和各自的具体生成器之间的关系,在org.hibernate.id.factory.internal.DefaultIdentifierGeneratorFactory中指定了:
//Constructs a new DefaultIdentifierGeneratorFactory. public DefaultIdentifierGeneratorFactory() { register( "uuid2", UUIDGenerator.class); register( "guid", GUIDGenerator.class); register( "uuid", UUIDHexGenerator.class); register( "uuid.hex", UUIDHexGenerator.class); register( "hilo", TableHiLoGenerator.class); register( "assigned", Assigned.class); register( "identity", IdentityGenerator.class); register( "select", SelectGenerator.class); register( "sequence", SequenceGenerator.class); register( "seqhilo", SequenceHiLoGenerator.class); register( "increment", IncrementGenerator.class); register( "foreign", ForeignGenerator.class); register( "sequence-identity", SequenceIdentityGenerator.class); register( "enhanced-sequence", SequenceStyleGenerator.class); register( "enhanced-table", TableGenerator.class); }
如果想要不同的表使用相同的主键生成器,可以把他的generator的name属性设为相同即可,例如:
@GeneratedValue(name="id1") @GenericGenerator(name="id1",strategy="identity")
上面十二种策略,加上native,hibernate一共默认支持十三种生成策略
1、native
@GeneratedValue(generator = "paymentableGenerator") @GenericGenerator(name = "paymentableGenerator", strategy = "native")
2、uuid
@GeneratedValue(generator = "paymentableGenerator") @GenericGenerator(name = "paymentableGenerator", strategy = "uuid")
3、hilo
@GeneratedValue(generator = "paymentableGenerator") @GenericGenerator(name = "paymentableGenerator", strategy = "hilo")
4、assigned
@GeneratedValue(generator = "paymentableGenerator") @GenericGenerator(name = "paymentableGenerator", strategy = "assigned")
5、identity
@GeneratedValue(generator = "paymentableGenerator") @GenericGenerator(name = "paymentableGenerator", strategy = "identity")
6、select
@GeneratedValue(generator = "paymentableGenerator") @GenericGenerator(name="select", strategy="select", parameters = { @Parameter(name = "key", value = "idstoerung") })
7、sequence
@GeneratedValue(generator = "paymentableGenerator") @GenericGenerator(name = "paymentableGenerator", strategy = "sequence", parameters = { @Parameter(name = "sequence", value = "seq_payablemoney") })
8、seqhilo
@GeneratedValue(generator = "paymentableGenerator") @GenericGenerator(name = "paymentableGenerator", strategy = "seqhilo", parameters = { @Parameter(name = "max_lo", value = "5") })
9、increment
@GeneratedValue(generator = "paymentableGenerator") @GenericGenerator(name = "paymentableGenerator", strategy = "increment")