我的实体类

@Data
@Entity
@Table(name = "pl_transactions")
public class PlTransactions{
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;

    @Version
    @Column(name = "version")
    private Long version;

    @Column(name = "id", insertable = false, updatable = false)
    private Integer _id;
    @Column(name = "version", insertable = false, updatable = false)
    private Long _version;

    @Column(name = "no_ref_no")
    private String noRefNo;
}

我的主存储库

@RepositoryRestResource(collectionResourceRel = "pl-transactions", path = "pl-transactions")
public interface PlTransactionsRepository extends PagingAndSortingRepository<PlTransactions, Integer>, JpaSpecificationExecutor<PlTransactions>,PlTransactionsRepositoryCustom {
}

我的自定义存储库

@Repository
public class PlTransactionsRepositoryCustomImpl implements PlTransactionsRepositoryCustom{
    @Autowired
    @PersistenceContext
    EntityManager entityManager;

    @Override
    public PlTransactionReport getTrxAmtOnly(Specification spec){
        PlTransactionReport plTransactionReport = new PlTransactionReport();
        CriteriaBuilder builder = entityManager.getCriteriaBuilder();
        CriteriaQuery<BigDecimal> query = builder.createQuery(BigDecimal.class);
        Root<PlTransactions> root = this.applySpecificationToCriteria(spec,query);
        query.select(builder.sum(root.get("trxAmt").as(BigDecimal.class)));
        TypedQuery<BigDecimal> typedQuery = entityManager.createQuery(query);
        typedQuery.getSingleResult();
        return plTransactionReport;
    }

    private Root<PlTransactions> applySpecificationToCriteria(Specification spec, CriteriaQuery<BigDecimal> query){
        Root<PlTransactions> root = query.from(PlTransactions.class);
        if(spec == null){
            return root;
        }
        CriteriaBuilder builder = entityManager.getCriteriaBuilder();
        Predicate predicate = spec.toPredicate(root,query,builder);
        if(predicate != null){
            query.where(predicate);
        }
        return root;
    }
}

我在网上搜索了一下，发现我必须使用persistance.xml注册它，但我手动尝试了一下，但仍然出现了这个错误，我尝试使用intellij生成它，但我的intellij idea marketplace中不存在jpa persistence的插件。请参考我使用的Intellij Idea 2020.3.4（社区版）