hibernate注解(annoation)使用id主键生成策略
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
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@Id
@GeneratedValue
(GenerationType.AUTO)
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就可以用hibernate特有以下用法来实现
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@GeneratedValue
(strategy = GenerationType.AUTO)
@GenericGenerator
(name =
"paymentableGenerator"
, strategy =
"native"
)
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使用@GeneratedValue
1、针对mysql,oracle,sqlserver数据库可以同时使用
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@Id
@GeneratedValue
(strategy = GenerationType.AUTO)
@GenericGenerator
(name =
"paymentableGenerator"
, strategy =
"native"
)
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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:
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//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
);
}
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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：
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@GeneratedValue
(name=
"id1"
)
@GenericGenerator
(name=
"id1"
,strategy=
"identity"
)
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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
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@GeneratedValue
(generator =
"paymentableGenerator"
)
@GenericGenerator
(name =
"paymentableGenerator"
, strategy =
"native"
)
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2、uuid
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@GeneratedValue
(generator =
"paymentableGenerator"
)
@GenericGenerator
(name =
"paymentableGenerator"
, strategy =
"uuid"
)
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3、hilo
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@GeneratedValue
(generator =
"paymentableGenerator"
)
@GenericGenerator
(name =
"paymentableGenerator"
, strategy =
"hilo"
)
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4、assigned
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@GeneratedValue
(generator =
"paymentableGenerator"
)
@GenericGenerator
(name =
"paymentableGenerator"
, strategy =
"assigned"
)
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5、identity
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@GeneratedValue
(generator =
"paymentableGenerator"
)
@GenericGenerator
(name =
"paymentableGenerator"
, strategy =
"identity"
)
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6、select
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@GeneratedValue
(generator =
"paymentableGenerator"
)
@GenericGenerator
(name=
"select"
, strategy=
"select"
, parameters = {
@Parameter
(name =
"key"
, value =
"idstoerung"
) })
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7、sequence
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@GeneratedValue
(generator =
"paymentableGenerator"
)
@GenericGenerator
(name =
"paymentableGenerator"
, strategy =
"sequence"
, parameters = {
@Parameter
(name =
"sequence"
, value =
"seq_payablemoney"
) })
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8、seqhilo
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@GeneratedValue
(generator =
"paymentableGenerator"
)
@GenericGenerator
(name =
"paymentableGenerator"
, strategy =
"seqhilo"
, parameters = {
@Parameter
(name =
"max_lo"
, value =
"5"
) })
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9、increment
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@GeneratedValue
(generator =
"paymentableGenerator"
)
@GenericGenerator
(name =
"paymentableGenerator"
, strategy =
"increment"
)
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