通过联接表的单向关联
@Entity
class Patient {
@OneToMany
private Collection<Vehicle> vehicles = new ArrayList<Vehicle>();
}
@Entity
class Vehicle {
}
通过联接表的双向关联
@Entity
class Patient {
@OneToMany
private Collection<Vehicle> vehicles = new ArrayList<Vehicle>();
}
@Entity
class Vehicle {
@ManyToOne(fetch = FetchType.LAZY)
private Patient patient;
}
通过外键进行单向关联
@Entity
class Patient {
@OneToMany
@JoinColumn
private Collection<Vehicle> vehicles = new ArrayList<Vehicle>();
}
@Entity
class Vehicle {
}
通过外键进行双向关联
@Entity
class Patient {
@OneToMany(mappedBy = "patient")
private Collection<Vehicle> vehicles = new ArrayList<Vehicle>();
}
@Entity
class Vehicle {
@ManyToOne(fetch = FetchType.LAZY)
private Patient patient;
}
通过外键与外列名称说明的双向关联
@Entity
class Patient {
@OneToMany(mappedBy = "patient")
private Collection<Vehicle> vehicles = new ArrayList<Vehicle>();
}
@Entity
class Vehicle {
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name="patient_id")
private Patient patient;
}
这是使用的基本起点@JoinColumn。
要验证的外键（patient_id在Vehicle表）中可以使用患者台真正映射@JoinColumn(nullable = false)
@Entity
class Vehicle {
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name="patient_id", nullable = false)
private Patient patient
}
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