java.lang.IllegalStateException：沒有超上查詢

Question

發現我有以下

@Entity 
@Table(name = "PROJECTS") 
public class Project implements Serializable { 

    @Id 
    private Integer SlNo; 

    @Id 
    private Long projectNo; 

    private Date projectDate; 
} 

和DAO類

CriteriaBuilder cb = entityManager.getCriteriaBuilder(); 

CriteriaQuery<Long> countQ = cb.createQuery(Long.class); 
Root<Project> empCount = countQ.from(Project.class); 
countQ.select(cb.count(empCount)); 

TypedQuery<Long> countquery = entityManager.createQuery(countQ);// error in this line 

我得到異常java.lang.IllegalStateException: No supertype found在上述行。我該如何解決或解決此問題？看起來有一個bug，有沒有解決這個問題的方法？

我使用Hibernate 4.1.0.Final

Answer 1

我已經解決了這個問題，通過在主鍵類使用Entity類@EmbeddedId和@Embeddable。

@Entity 
@Table(name = "PROJECTS") 
public class Project { 
@Column(name = "SL_NO" , insertable = false, updatable = false) 
private Integer SlNo; 
@Column(name = "PROJECT_NO" , insertable = false, updatable = false) 
private Long projectNo; 
private Date projectDate; 

@EmbeddedId 
ProjectPK projectPK; 

和主鍵類

@Embeddable 
public class ProjectPK implements Serializable { 
@Column(name = "SL_NO") 
private Integer SlNo; 
@Column(name = "PROJECT_NO") 
private Long projectNo; 

//with hashCode and equals implementation