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我使用@JoinedColumns嘗試派生實體合併實體，不能與派生實體
讓我告訴你我的代碼，
下面是SQL代碼，
create table TBL_EMPLOYEE_FIVE(
EMP_ID integer ,
NAME varchar(50),
COUNTRY varchar(50),
MGR_ID integer,
MGR_COUNTRY varchar(50),
constraint PK_COMPOSIT_001AD primary key(EMP_ID,COUNTRY),
constraint FK_COMPO_0foreign key(MGR_ID,MGR_COUNTRY) references TBL_EMPLOYEE_FIVE
)
這是映射實體的代碼如下，
package com.entities.derived;
@Entity
@Table(name="TBL_EMPLOYEE_FIVE")
@IdClass(EmployeeId.class)
public class EmployeeOne implements Serializable{
// contructors
@Id
@Column(name="EMP_ID")
private Integer employeeId;
@Id
@Column(name="COUNTRY")
private String empCountry;
@Column(name="NAME")
private String employeeName;
@ManyToOne(cascade= {CascadeType.PERSIST, CascadeType.PERSIST},
fetch= FetchType.LAZY,
targetEntity=EmployeeOne.class)
@JoinColumns({
@JoinColumn(name="MGR_ID",referencedColumnName="EMP_ID"),
@JoinColumn(name="MGR_COUNTRY",referencedColumnName="COUNTRY")
})
private EmployeeOne manager;
@OneToMany(cascade={CascadeType.PERSIST, CascadeType.PERSIST},mappedBy="manager")
private Set<EmployeeOne> employees;
// getters, setters, hashcode and equals implementation
}
這是以下代碼的類ID，
@Embeddable
public class EmployeeId implements Serializable{
public EmployeeId(){}
public EmployeeId(Integer employeeId,String empCountry){
this.employeeId = employeeId;
this.empCountry = empCountry;
}
private Integer employeeId;
private String empCountry;
// getters, hashcode and equals implementation
}
寫在主方法和代碼正確地工作而不會異常如下，
以用於存留新僱員，
private static int generateId(EntityManager em,String country)throws Exception{
Query q = em.createQuery("select max(e.employeeId) from EmployeeOne e where e.empCountry = '"+country+"'");
List list = q.getResultList();
int count = 0;
if(list != null && list.size() > 0){
count = Integer.parseInt(String.valueOf((list.get(0) != null) ? list.get(0) : "0"));
}
count++;
return count;
}
插入新僱員，
private static void insertEmployee2(EntityManager em) throws Exception{
EmployeeOne manager = new EmployeeOne("Rajkumar Bahadur", "NEPAL");
manager.setEmployeeId(generateId(em, manager.getEmpCountry()));
Set<EmployeeOne> employees = new HashSet<EmployeeOne>();
int count = generateId(em, "FIJI");
employees.add(new EmployeeOne(count,"Okajima Fahim","FIJI",manager));
employees.add(new EmployeeOne(++count,"Jabulani Xitwo","FIJI",manager));
manager.setEmployees(employees);
em.persist(manager);
}
提取員工是，
private static void getEmployees(EntityManager em) throws Exception{
EmployeeOne manager = em.find(EmployeeOne.class, new EmployeeId(3,"CHINA"));
Set<EmployeeOne> employees = manager.getEmployees();
for(EmployeeOne emp : employees){
System.out.println(emp);
}
}
以上所有方法都運行良好。
但不工作是合併的唯一代碼，代碼如下
private static void updateEmployee(EntityManager em) throws Exception{
EmployeeOne manager = em.find(EmployeeOne.class, new EmployeeId(3,"CHINA"));
Set<EmployeeOne> employees = manager.getEmployees();
int count = generateId(em, "IRAN");
employees.add(new EmployeeOne(count,"Zaid Khan","IRAN",manager));
employees.add(new EmployeeOne(++count,"Maqbool Ansari","IRAN",manager));
em.merge(manager);
}
這是我得到的是例外，
javax.persistence.EntityNotFoundException: Unable to find com.entities.derived.EmployeeOne with id [email protected]
at org.hibernate.ejb.Ejb3Configuration$Ejb3EntityNotFoundDelegate.handleEntityNotFound(Ejb3Configuration.java:155)
at org.hibernate.event.internal.DefaultLoadEventListener.load(DefaultLoadEventListener.java:210)
at org.hibernate.event.internal.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:251)
at org.hibernate.event.internal.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:148)
....
能否請你告訴我，我在哪裏腳麻