使用@IdClass用於存儲實體組合大主鍵，但未能堅持

Question

我的ID級別如下，

public class EmployeeId implements Serializable{ 
    public EmployeeId(){} 
    public EmployeeId(Integer id, String country){ 
     this.id = id; 
     this.country = country; 
    } 

    private Integer id; 
    private String country; 

    @Override 
    public int hashCode(){   
     return this.getCountry().hashCode() + getId(); 
    } 

    @Override 
    public boolean equals(Object o){ 
     boolean flag = false; 
     EmployeeId myId = (EmployeeId) o; 

     if((o instanceof EmployeeId) 
       && (this.getCountry().equals(myId.getCountry())) 
       && (this.id == myId.getId())){ 
      flag = true; 
     } 
     return flag; 
    } 
// rest of the code with getters only 
} 

下面是使用

@Entity 
@IdClass(EmployeeId.class) 
@Table(name="TBL_EMPLOYEE_FOUR") 
public class EmployeeEntityTwo { 

    public EmployeeEntityTwo(){} 
    public EmployeeEntityTwo(Integer id,String country, String empName){ 
     this.country = country; 
     this.employeeId = id; 
     this.empName = empName; 
    } 

    @Id 
    @Column(name="ID") 
    private Integer employeeId; 

    @Id 
    @Column(name="COUNTRY",length=50) 
    private String country; 

    @Column(name="NAME",length=50) 
    private String empName; 
// getters and setters 
} 

這是我的表

我的實體

create table TBL_EMPLOYEE_FOUR(
    ID integer, 
    COUNTRY varchar(50), 
    NAME varchar(50), 
    constraint PK_EMP_00239 primary key(ID,COUNTRY) 
) 

這就是我試圖運行

private static void idClassStore(EntityManager em) throws Exception{ 
    List<EmployeeEntityTwo> employees = Arrays.asList(new EmployeeEntityTwo(12, "KENYA", "Ridushi Ogambe"), 
                 new EmployeeEntityTwo(13, "GHANA", "Mikila Hanza"), 
                 new EmployeeEntityTwo(14, "EGYPT", "Abdul Hameed Fagdaul"), 
                 new EmployeeEntityTwo(15, "MOROCCO", "Jamil Mahmoud"), 
                 new EmployeeEntityTwo(16, "LIBERIA", "Robert Damus")); 

    for(EmployeeEntityTwo employee : employees){ 
     em.persist(employee);    
     } 
} 

，但我得到我都用一個異常

Caused by: org.hibernate.AnnotationException: Property of @IdClass not found in entity com.entities.EmployeeEntityTwo: id 

我使用JPA與Hibernate作爲持久性提供，

但@IdClass是進口javax.persistence.IdClass的;

那麼，是我走錯了，

Answer 1

我已經發現瞭解決方案：

的「ID」字段中的類EmployeeEntityTwo和EmployeeId應該是相同的。

// EmployeeId.java; 
private Integer id; 

應該

// EmployeeId.java; 
private Integer employeeId; 

我分別調整，吸氣，和它的工作。

---

從javax.persistence.IdClass的JavaDoc：

在主鍵類的字段或屬性和實體的主鍵字段或屬性的名稱必須對應和它們的類型必須是相同的。