HiLo发电机策略不起作用

Question

我是hibernate的新手.我想要做的是用于@CollectionId为我的Address类生成一个标识符.我已经使用了Collection接口.但是当我使用@GenericGenerator并将策略设置为hilo时,它会抛出异常.这是我的代码:

@Entity
@Table(name = "USER_DETAILS")
public class UserDetails {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int userId;
    private String userName;

    @ElementCollection
    @JoinTable(name="USER_ADDRESS",
        joinColumns=@JoinColumn(name="USER_ID")
    )

    @GenericGenerator(name = "hilo-gen", strategy = "hilo")
    @CollectionId(columns = { @Column(name="ADDRESS_ID") }, generator = "hilo-gen", type = @Type(type="long"))
    private Collection<Address> address = new ArrayList<Address>();

    public int getUserId() {
        return userId;
    }

    public void setUserId(int userId) {
        this.userId = userId;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public Collection<Address> getAddress() {
        return address;
    }

    public void setAddress(List<Address> address) {
        this.address = address;
    }
}

我得到以下异常:

Exception in thread "main" org.hibernate.MappingException: Could not instantiate id generator [entity-name=null]
    at org.hibernate.id.factory.internal.DefaultIdentifierGeneratorFactory.createIdentifierGenerator(DefaultIdentifierGeneratorFactory.java:121)
    at org.hibernate.mapping.SimpleValue.createIdentifierGenerator(SimpleValue.java:259)
    at org.hibernate.persister.collection.AbstractCollectionPersister.<init>(AbstractCollectionPersister.java:429)
    at org.hibernate.persister.collection.BasicCollectionPersister.<init>(BasicCollectionPersister.java:57)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
    at org.hibernate.persister.internal.PersisterFactoryImpl.createCollectionPersister(PersisterFactoryImpl.java:152)
    at org.hibernate.persister.internal.PersisterFactoryImpl.createCollectionPersister(PersisterFactoryImpl.java:140)
    at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:408)
    at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:444)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:708)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:724)
    at com.hbt.HibernateTest.main(HibernateTest.java:35)
Caused by: java.lang.UnsupportedOperationException: Support for 'hilo' generator has been removed
    at org.hibernate.id.factory.internal.DefaultIdentifierGeneratorFactory.getIdentifierGeneratorClass(DefaultIdentifierGeneratorFactory.java:132)
    at org.hibernate.id.factory.internal.DefaultIdentifierGeneratorFactory.createIdentifierGenerator(DefaultIdentifierGeneratorFactory.java:112)
    ... 14 more

我正在使用最新的休眠.我该怎么办？

Answer 1

Hilo不再受支持,这应该可行

@GenericGenerator(name="sequence-gen",strategy="sequence")

Answer 2

如果我们使用的是MySQL会更好使用@GenericGenerator的增量策略。

1. 顺序 -Oracle，Postgresql支持这种策略。

2. 增量 -MySql支持这种策略。

   @ElementCollection
   @JoinTable(name="USER_ADDRESS", joinColumns=@JoinColumn(name="USER_ID"))
   @GenericGenerator(name = "increment-gen", strategy = "increment")
   @CollectionId(columns = { @Column(name="ADDRESS_ID") }, generator = "increment-gen", type = @Type(type="long"))
   private Collection<Address> listOfAddress = new ArrayList<>();
   

当我将序列策略与MySql一起使用时，遇到了一个问题，其中我的ADDRESS_ID 无法正确递增。