休眠兩個父母一個孩子映射

Question

我有以下場景：有公司和員工。每家公司都有一組員工。每個員工都可以爲幾家公司工作。所以，我實現了以下關係式：

Company.class：

@JoinTable(name = "company_employee", joinColumns = @JoinColumn(name = "company_id") , inverseJoinColumns = @JoinColumn(name = "employee_id")) 
@ManyToMany(fetch = FetchType.LAZY) 
private List<Employee> employees; 

Employee.class：

@JoinTable(name = "company_employee", joinColumns = @JoinColumn(name = "employee_id") , inverseJoinColumns = @JoinColumn(name = "company_id")) 
@ManyToMany(fetch = FetchType.LAZY) 
private List<Company> companies; 

顯然，爲幾家公司工作，每個員工應該有分配給幾個不重疊的時間表他或她工作的每個公司。 此外，每個組合公司員工都應該有一個時間表列表，因爲有時舊時間表會過期，新時間表會生效。 所以我也有Schedule.class，這是應該有child to parent @ManyToOne關係既Company和Employee，並應工作方式如下：各Schedule，因此List<Schedule>應該對應Company和Employee實例只有一個組合。 如何實現這種關係？

更新1

我只記住添加@OneToMany Schedule關係到每個Company和Employee，但後來我需要把的Schedule兩個實例來Company和Employee每一次，而這種方式就是不看起來不錯，現在對我來說也不明顯，如何取回它。 所以任何幫助將不勝感激。

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這個職位是更新，以顯示實際生活的場景我有，不只是通用ENTITY1，ENTITY2，ENTITY3名字的類。

更新2

我接受了答案，但我不能使用它，如果計劃包含列表。 根據我的計劃，Schedule應該包含List<Vacation>以瞭解一年以上的Vacations和List的Days，它們中的每一個都顯示特定的星期幾，休息時間和當天結束的開始。那些Days對於每個Schedule實例也是唯一的。

它應該是像下面的東西，但顯然現在我沒有schedule_id，所以如何將這些列表連接到Schedule？

@OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL, orphanRemoval = true) 
@JoinColumn(name = "schedule_id") 
private List<Vacation> vacations; 

@JoinTable(name = "schedule_week", joinColumns = @JoinColumn(name = "schedule_id") , inverseJoinColumns = @JoinColumn(name = "day_id")) 
@OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL, orphanRemoval = true) 
private List<Day> week; 

如何將這些列表包含在內？

Answer 1

我想推薦以下解決方案。

一個embeddable類，其中包含特定時間表的Company和Employee。

@Embeddable 
public class ScheduleOwner implements Serializable{ 

    @MapsId("id") 
    @ManyToOne(cascade = CascadeType.ALL) 
    Company c; 

    @MapsId("id") 
    @ManyToOne(cascade = CascadeType.ALL) 
    Employee e; 
} 

的Schedule類嵌入ScheduleOwner實例。

@Entity 
public class Schedule { 

    @EmbeddedId 
    ScheduleOwner owner; 

    String description; 
} 

的Company和Employee類（沒有做他們的變化）

@Entity 
public class Company { 

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

    @JoinTable(name = "company_employee", joinColumns = @JoinColumn(name = "company_id") , inverseJoinColumns = @JoinColumn(name = "employee_id")) 
    @ManyToMany(fetch = FetchType.LAZY) 
    private List<Employee> employees; 
} 


@Entity 
public class Employee { 

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

    @JoinTable(name = "company_employee", joinColumns = @JoinColumn(name = "employee_id") , inverseJoinColumns = @JoinColumn(name = "company_id")) 
    @ManyToMany(fetch = FetchType.LAZY) 
    private List<Company> companies; 
} 

更新1

下面是你如何能保存和讀取結果。

Employee e1 = new Employee(); 
    Company c1 = new Company(); 
    c1.employees.add(e1); 

    e1.companies.add(c1); 

    ScheduleOwner so = new ScheduleOwner(); 
    so.c = c1; 
    so.e = e1; 

    Schedule s = new Schedule(); 
    s.owner = so; 

    session.save(c1); 
    session.save(e1); 
    session.save(s); 

    // below query will fetch from schedule, where company id = 9 
    Schedule ss = (Schedule) session.createQuery("From Schedule sh where sh.owner.c.id = 9").uniqueResult(); 

UPDATE 2

@Entity 
public class Company { 

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

    @JoinTable(name = "company_employee", joinColumns = @JoinColumn(name = "company_id", referencedColumnName="id") 
             , inverseJoinColumns = @JoinColumn(name = "employee_id", referencedColumnName="id")) 
    @ManyToMany(fetch = FetchType.LAZY) 
    List<Employee> employees = new ArrayList<>(); 

    String name; 
} 

@Entity 
public class Employee { 

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

    @ManyToMany(fetch = FetchType.LAZY, mappedBy = "employees") 
    List<Company> companies = new ArrayList<>(); 

    String name; 
} 

@Entity 
public class Schedule { 

    @Id 
    @GeneratedValue(strategy = GenerationType.IDENTITY) 
    int schedule_id; 

    @ManyToOne 
    @JoinColumn(name = "company_id", insertable = false, updatable = false) 
    private Company company; 
    @ManyToOne 
    @JoinColumn(name = "employee_id", insertable = false, updatable = false) 
    private Employee employee; 

    String description; 

    @OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL, orphanRemoval = true, mappedBy = "schedule") 
    List<Vacation> vacations; 

} 

@Entity 
public class Vacation { 

    @Id 
    @GeneratedValue(strategy = GenerationType.IDENTITY) 
    private int vacation_id; 

    @ManyToOne 
    @JoinColumn(name = "schedule_id") 
    Schedule schedule; 

    @OneToMany(mappedBy = "vacation") 
    List<Day> days; 
} 

Day實體直接涉及Vacation。不要Schedule。

@Entity 
public class Day { 

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


    @ManyToOne 
    @JoinColumn(name = "vacation_id") 
    Vacation vacation; 
} 

希望這會有所幫助。