我现在正面临一个让我抓狂的问题。
我想创建自己的IdentifierGenerator来管理特定格式的ID。

public class CustomGenerator implements IdentifierGenerator {

    private static final String REQUEST = "SELECT CURRVAL('sequence')";

    private final String prefixFormat = "PREFIX-%s";

    @Override
    public Serializable generate(SessionImplementor session, Object object) throws HibernateException {
        final String prefix = getPrefix();
        Session sessionHibernate = (Session) session;
        Query query = sessionHibernate.createSQLQuery(REQUEST );
        Object obj = query.uniqueResult();
        return null;
    }

    private String getPrefix() {
        final Calendar date = Calendar.getInstance();
        DateFormat dateFormat = new SimpleDateFormat("yyyyMM");
        return String.format(prefixFormat, dateFormat.format(date.getTime()));
    }

}

我的Junit测试：

@Test
@Transactional
public void addEntity() {
    final Entity entity= new Entity();
    final long count = this.entityRepository.count();

    this.entityRepository.saveAndFlush(rex);

    assertEquals(count + 1, this.entityRepository.count());
}

我的实体：

@Entity
@Table(name = "ENTITY")
public class Entity {

    @Id
    @GenericGenerator(name = "sequence", strategy = "[...]CustomGenerator")
    @GeneratedValue(generator = "sequence")
    @Column(name = "ENTITY_ID")
    private Integer entityId;

    [...]
}

我的JUnit测试崩溃- Stacktrace：

org.springframework.dao.InvalidDataAccessResourceUsageException: could not  prepare statement; SQL [SELECT CURRVAL('sequence_rex_id')]; nested exception is org.hibernate.exception.SQLGrammarException: could not prepare statement
    at org.springframework.orm.jpa.vendor.HibernateJpaDialect.convertHibernateAccessException(HibernateJpaDialect.java:238)
    at org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:221)
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.translateExceptionIfPossible(AbstractEntityManagerFactoryBean.java:417)
    at org.springframework.dao.support.ChainedPersistenceExceptionTranslator.translateExceptionIfPossible(ChainedPersistenceExceptionTranslator.java:59)
    at org.springframework.dao.support.DataAccessUtils.translateIfNecessary(DataAccessUtils.java:213)

数据库：HSQLDB（测试）、POSTGRESQL（生产）
有人知道吗？
对于我可能犯的任何错误，我感到抱歉。英语不是我的母语。