基于Hibernate Anotation的ID生成策略.docx

基于按annotation的hibernate主键生成策略文章分类:Java编程 基于按annotation的hibernate主键生成策略 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 Java代码 1.Id 2.GeneratedValue(GenerationType.AUTO) Id GeneratedValue(GenerationType.AUTO) 就可以用hibernate特有以下用法来实现 Java代码 1.GeneratedValue(generator = paymentableGenerator) 2.GenericGenerator(name = paymentableGenerator, strategy = assigned) GeneratedValue(generator = paymentableGenerator) GenericGenerator(name = paymentableGenerator, strategy = assigned) GenericGenerator的定义: Java代码 1.Target(PACKAGE, TYPE, METHOD, FIELD) 2.Retention(RUNTIME) 3.public interface GenericGenerator 4. 5.String name(); 6. 7.String strategy(); 8. 9.Parameter parameters() default ; 10. Target(PACKAGE, TYPE, METHOD, FIELD) Retention(RUNTIME) public interface GenericGenerator String name(); String strategy(); Parameter parameters() default ; 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。 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.IdentifierGeneratorFactory中指定了, Java代码 1.static 2. GENERATORS.put(uuid, UUIDHexGenerator.class); 3. GENERATORS.put(hilo, TableHiLoGenerator.class); 4. GENERATORS.put(assigned, Assigned.class); 5. GENERATORS.put(identity, IdentityGenerator.class); 6. GENERATORS.put(select, SelectGenerator.class); 7. GENERATORS.put(sequence, SequenceGenerator.class); 8. GENERATORS.put(seqhilo, SequenceHiLoGenerator.class); 9. GENERATORS.put(increment, IncrementGenerator.class); 10. GENERATORS.put(foreign, ForeignGenerator.class); 11. GENERATORS.put(guid, GUIDGenerator.class); 12. GENERATORS.put(uuid.hex, UUIDHexGenerator.class); /uuid.hex is deprecated 13. GENERATORS.put(sequence-identity, SequenceIdentityGenerator.class); 14. static GENERATORS.put(uuid, UUIDHexGenerator.class); GENERATORS.put(hilo, TableHiLoGenerator.class); GENERATORS.put(assigned, Assigned.class); GENERATORS.put(identity, IdentityGenerator.class); GENERATORS.put(select, SelectGenerator.class); GENERATORS.put(sequence, SequenceGenerator.class); GENERATORS.put(seqhilo, SequenceHiLoGenerator.class); GENERATORS.put(increment, IncrementGenerator.class); GENERATORS.put(foreign, ForeignGenerator.class); GENERATORS.put(guid, GUIDGenerator.class); GENERATORS.put(uuid.hex, UUIDHexGenerator.class); /uuid.hex is deprecated GENERATORS.put(sequence-identity, SequenceIdentityGenerator.class); 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 Java代码 1.GeneratedValue(generator = paymentableGenerator) 2.GenericGenerator(name = paymentableGenerator, strategy = native) GeneratedValue(generator = paymentableGenerator) GenericGenerator(name = paymentableGenerator, strategy = native) 2、uuid Java代码 1.GeneratedValue(generator = paymentableGenerator) 2.GenericGenerator(name = paymentableGenerator, strategy = uuid) GeneratedValue(generator = paymentableGenerator) GenericGenerator(name = paymentableGenerator, strategy = uuid) 3、hilo Java代码 1.GeneratedValue(generator = paymentableGenerator) 2.GenericGenerator(name = paymentableGenerator, strategy = hilo) GeneratedValue(generator = paymentableGenerator) GenericGenerator(name = paymentableGenerator, strategy = hilo) 4、assigned Java代码 1.GeneratedValue(generator = paymentableGenerator) 2.GenericGenerator(name = paymentableGenerator, strategy = assigned) GeneratedValue(generator = paymentableGenerator) GenericGenerator(name = paymentableGenerator, strategy = assigned) 5、identity Java代码 1.GeneratedValue(generator = paymentableGenerator) 2.GenericGenerator(name = paymentableGenerator, strategy = identity) GeneratedValue(generator = paymentableGenerator) GenericGenerator(name = paymentableGenerator, strategy = identity) 6、select Java代码 1.GeneratedValue(generator = paymentableGenerator) 2.GenericGenerator(name=select, strategy=select, 3. parameters = Parameter(name = key, value = idstoerung) ) GeneratedValue(generator = paymentableGenerator) GenericGenerator(name=select, strategy=select, parameters = Parameter(name = key, value = idstoerung) ) 7、sequence Java代码 1.GeneratedValue(generator = paymentableGenerator) 2.GenericGenerator(name = paymentableGenerator, strategy = sequence, 3. parameters = Parameter(name = sequence, value = seq_payablemoney) ) GeneratedValue(generator = paymentableGenerator) GenericGenerator(name = paymentableGenerator, strategy = sequence, parameters = Parameter(name = sequence, value = seq_payablemoney) ) 8、seqhilo Java代码 1.GeneratedValue(generator = paymentableGenerator) 2.GenericGenerator(name = paymentableGenerator, strategy = seqhilo, 3. parameters = Parameter(name = max_lo, value = 5) ) GeneratedValue(generator = paymentableGenerator) GenericGenerator(name = paymentableGenerator, strategy = seqhilo, parameters = Parameter(name = max_lo, value = 5) ) 9、increment Java代码 1.GeneratedValue(generator = paymentableGenerator) 2.GenericGenerator(name = paymentableGenerator, strategy = increment) GeneratedValue(generator = paymentableGenerator) GenericGenerator(name = paymentableGenerator, strategy = increment) 10、foreign Java代码 1.GeneratedValue(generator = idGenerator) 2.GenericGenerator(name = idGenerator, strategy = foreign, 3. parameters = Parameter(name = property, value = employee) ) GeneratedValue(generator = idGenerator) GenericGenerator(name = idGenerator, strategy = foreign, parameters = Parameter(name = property, value = employee) ) 注意：直接使用PrimaryKeyJoinColumn 报错（?） Java代码 1.OneToOne(cascade = CascadeType.ALL) 2.PrimaryKeyJoinColumn OneToOne(cascade = CascadeType.ALL) PrimaryKeyJoinColumn 例如 Java代码 1.Entity 2.public class Employee 3. Id Integer id; 4. 5. OneToOne PrimaryKeyJoinColumn 6. EmployeeInfo info; 7. . 8. Entity public class Employee Id Integer id; OneToOne PrimaryKeyJoinColumn EmployeeInfo info; . 应该为 Java代码 1.Entity 2.public class Employee 3. Id 4. GeneratedValue(generator = idGenerator) 5. GenericGenerator(name = idGenerator, strategy = foreign, 6. parameters = Parameter(name = property, value = info) ) 7. Integer id; 8. 9. OneToOne 10. EmployeeInfo info; 11. . 12. Entity public class Employee Id GeneratedValue(generator = idGenerator) GenericGenerator(name = idGenerator, strategy = foreign, parameters = Parameter(name = property, value = info) ) Integer id; OneToOne EmployeeInfo info; . 11、guid Java代码 1.GeneratedValue(generator = paymentableGenerator) 2.GenericGenerator(name = paymentableGenerator, strategy = guid) GeneratedValue(generator = paymentableGenerator) GenericGenerator(name = paymentableGenerator, strategy = guid) 12、uuid.hex Java代码 1.GeneratedValue(generator = paymentableGenerator) 2.GenericGenerator(name = paymentableGenerator, strategy = uuid.hex) GeneratedValue(generator = paymentableGenerator) GenericGenerator(name = paymentableGenerator, strategy = uuid.hex) 13、sequence-identity Java代码 1.GeneratedValue(generator = paymentableGenerator) 2.GenericGenerator(name = paymentableGenerator, strategy = sequence-identity, 3. parameters = Parameter(name = sequence, value = seq_payablemoney) ) GeneratedValue(generator = paymentableGenerator) GenericGenerator(name = paymentableGenerator, strategy = sequence-identity, parameters = Parameter(name = sequence, value = seq_payablemoney) ) 四、通过GenericGenerator自定义主键生成策略 如果实际应用中，主键策略为程序指定了就用程序指定的主键（assigned），没有指定就从sequence中取。 明显上面所讨论的策略都不满足，只好自己扩展了，集成assigned和sequence两种策略。 Java代码 Java代码 1. publicclassAssignedSequenceGeneratorextendsSequenceGeneratorimplements2. PersistentIdentifierGenerator,Configurable3. privateStringentityName;4. publicvoidconfigure(Typetype,Propertiesparams,Dialectdialect)throwsMappingException5. entityName=params.getProperty(ENTITY_NAME);6. if(entityName=null)7. thrownewMappingException(noentityname);super.configure(type,params,dialect);publicSerializablegenerate(SessionImplementorsession,Objectobj)throwsHibernateExceptionSerializableid=session.getEntityPersister(entityName,obj)getIdentifier(obj,session.getEntityMode();if(id=null)id=super.generate(session,obj);returnid;publicclassAssignedSequenceGeneratorextendsSequenceGeneratorimplementsPersistentIdentifierGenerator,ConfigurableprivateStringentityName;publicvoidconfigure(Typetype,Propertiesparams,Dialectdialect)throwsMappingExceptionentityName=params.getProperty(ENTITY_NAME);if(entityName=null)thrownewMappingException(noentityname);super.configure(type,params,dialect);publicSerializablegenerate(SessionImplementorsession,Objectobj)throwsHibernateExceptionSerializableid=session.getEntityPersister(entityName,obj).getIdentifier(obj,session.getEntityMode();if(id=null)id=super.generate(session,obj);returnid;public class AssignedSequenceGenerator extends SequenceGenerator implements PersistentIdentifierGenerator, Configurable private String entityName; public void configure(Type type, Properties params, Dialect dialect) throws MappingException entityName = params.getProperty(ENTITY_NAME); if (entityName=null) throw new MappingException(no entity name); super.configure(type, params, dialect); public Serializable generate(SessionImplementor session, Object obj) throws HibernateException Serializable id = session.getEntityPersist