如何使用 Hibernate 连接两个表的字段？

我有两个表和相关的 Java 映射。

CREATE TABLE country (
    code VARCHAR(3) PRIMARY KEY NOT NULL,
    name VARCHAR(100) NOT NULL
);


CREATE TABLE user (
    id INT PRIMARY KEY NOT NULL AUTO_INCREMENT,
    name VARCHAR(100) NOT NULL,
    country_code VARCHAR(3),
    FOREIGN KEY ( country_code ) REFERENCES country ( code )
);

这是我的 Java 实体。国家POJO：

@Entity
@Table(name = "country")
public class Country {

    @Id
    @Column (name = "code")
    private String code;

    @Column (name = "name")
    private String name;

用户 POJO：

@Entity
@Table(name = "user")
public class User implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;

    @Column(name = "name")
    private String name;

    @Column(name = "country_code")
    private String countryCode;

问题是我怎样才能加入Contry.code to User.countryCode在 Hibernate 中使用注释？当我使用 Hibernate 创建 User 对象时，我需要自动绑定这两个字段（代码和国家代码）。

你需要@OneToMany映射自Country to User实体和相应的@ManyToOne映射自User to Country:

@Entity
@Table(name = "country")
public class Country {

    @Id
    @Column (name = "code")
    private String code;

    @Column (name = "name")
    private String name;

    @OneToMany(mappedBy = "country")
    private Set<User> users;
}

@Entity
@Table(name = "user")
public class User implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;

    @Column(name = "name")
    private String name;

    @ManyToOne
    @JoinColumn(name = "country_code")
    private Country country;
}