什么是@JoinColumn以及如何在Hibernate中使用

通过联接表的单向关联

@Entityclass Patient {    @oneToMany    private Collection<Vehicle> vehicles = new ArrayList<Vehicle>();}@Entityclass Vehicle {}

通过联接表的双向关联

@Entityclass Patient {    @oneToMany    private Collection<Vehicle> vehicles = new ArrayList<Vehicle>();}@Entityclass Vehicle {    @ManyToOne(fetch = FetchType.LAZY)    private Patient patient;}

通过外键进行单向关联

@Entityclass Patient {    @oneToMany    @JoinColumn    private Collection<Vehicle> vehicles = new ArrayList<Vehicle>();}@Entityclass Vehicle {}

通过外键进行双向关联

@Entityclass Patient {    @oneToMany(mappedBy = "patient")    private Collection<Vehicle> vehicles = new ArrayList<Vehicle>();}@Entityclass Vehicle {    @ManyToOne(fetch = FetchType.LAZY)    private Patient patient;}

通过外键与外列名称说明的双向关联

@Entityclass Patient {    @oneToMany(mappedBy = "patient")    private Collection<Vehicle> vehicles = new ArrayList<Vehicle>();}@Entityclass 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)

@Entityclass Vehicle {    @ManyToOne(fetch = FetchType.LAZY)    @JoinColumn(name="patient_id", nullable = false)    private Patient patient}