我有以下场景:有公司和员工。每个公司都有一组员工。每个员工可以为多家公司工作。所以我实现了以下关系:
公司类:
@JoinTable(name = "company_employee", joinColumns = @JoinColumn(name = "company_id") , inverseJoinColumns = @JoinColumn(name = "employee_id") )
@ManyToMany(fetch = FetchType.LAZY)
private List<Employee> employees;
员工类:
@JoinTable(name = "company_employee", joinColumns = @JoinColumn(name = "employee_id") , inverseJoinColumns = @JoinColumn(name = "company_id") )
@ManyToMany(fetch = FetchType.LAZY)
private List<Company> companies;
显然,要为多家公司工作,每个员工都应该为他或她工作的每个公司分配多个不重叠的时间表。
此外,每个公司-员工组合都应该有一个时间表列表,因为有时旧时间表会过期,而新时间表会生效。
所以我也有 Schedule.class
,应该有 child to parent @ManyToOne
与 Company
的关系和 Employee
,并且应该按照以下方式工作:每个 Schedule
,因此,List<Schedule>
应该恰好对应于 Company
的一个组合和 Employee
实例。
如何实现这种关系?
更新 1
我只想添加 @OneToMany Schedule
与每个关系 Company
和 Employee
,但是我需要放置 Schedule
的实例都到Company
和 Employee
每次,这种方式看起来都不对,现在我也不清楚如何取回它。
因此,我们将不胜感激。
这篇文章已更新以展示我的真实场景,而不仅仅是类的通用 Entity1、Entity2、Entity3 名称。
更新 2
我接受了答案,但如果 Schedule 包含列表,我将无法使用它。
按照我的计划,Schedule
应包含 List<Vacation>
知道 Vacations
的集合一年多了,List
的 Days
,每个显示特定工作日的开始、休息和这一天的结束。那些Days
每个Schedule
也是独一无二的实例。
它应该是像下面这样的东西,但显然现在我没有 schedule_id
,那么如何将这些列表连接到 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;
如何正确包含这些列表?
最佳答案
我想建议以下解决方案。
一个可嵌入
类,其中包含用于特定计划的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;
}
Schedule
类嵌入了一个 ScheduleOwner
实例。
@Entity
public class Schedule {
@EmbeddedId
ScheduleOwner owner;
String description;
}
Company
和 Employee
类(未对它们进行任何更改)
@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
以下是您可以如何保存和获取结果。
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();
更新 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
实体直接与 Vacation
相关。不安排
。
@Entity
public class Day {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
@ManyToOne
@JoinColumn(name = "vacation_id")
Vacation vacation;
}
希望这对您有所帮助。
关于java - Hibernate 两父一子映射,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/34302585/