Question

我是Hibernate的新手，我正在尝试在Person和Vehicle类之间建立OneToMany / ManyToOne双向关系。在我的例子中，一个人可以有很多车辆而一辆车只属于一个人。我需要一个连接表：PERSON_VEHICLE，PERSON_ID和VEHICLE_ID作为列，VEHICLE表中有PERSON_ID列。这是我的班级设计：

人员类：

@Entity
public class Person {

@Id
@GeneratedValue
@Column(name = "PERSON_ID")
private int id;
private String name;
@OneToMany(cascade=CascadeType.ALL, mappedBy="person") 
private Collection<Vehicle> vehicleList = new ArrayList<>();

车辆类：

@Entity
public class Vehicle {

@Id
@GeneratedValue
@Column(name = "VEHICLE_ID")
private int id;
private String name;
@ManyToOne
@JoinColumn(name="PERSON_ID")
@JoinTable(name="PERSON_VEHICLE", joinColumns=@JoinColumn(name="VEHICLE_ID"),
inverseJoinColumns=@JoinColumn(name="PERSON_ID"))
private Person person;

以下是Hibernate生成的DDL。

create table Person (
    PERSON_ID integer not null auto_increment,
    name varchar(255),
    primary key (PERSON_ID)
)

create table Vehicle (
    VEHICLE_ID integer not null auto_increment,
    name varchar(255),
    primary key (VEHICLE_ID)
)

create table PERSON_VEHICLE (
    PERSON_ID integer,
    VEHICLE_ID integer not null,
    primary key (VEHICLE_ID)
)

alter table PERSON_VEHICLE 
    add index FK_h3d046x5uvbo53p8ms41hwqx (PERSON_ID), 
    add constraint FK_h3d046x5uvbo53p8ms41hwqx 
    foreign key (PERSON_ID) 
    references Person (PERSON_ID)

alter table PERSON_VEHICLE 
    add index FK_mtm2mn29hel3lbpl6i526w40v (VEHICLE_ID), 
    add constraint FK_mtm2mn29hel3lbpl6i526w40v 
    foreign key (VEHICLE_ID) 
    references Vehicle (VEHICLE_ID)

VEHICLE表没有PERSON_ID列。出了点问题，但我找不到问题所在。

Answer 1

oneToMany关系不需要连接表。只有两个表Person和Vehicle足以进行此映射。有关详细示例，请参阅This Example

OneToMany双向关联示例

1 个答案: