java - 使用@JoinTable的@ManyToMany注释的JPA问题

Question

我正在尝试在两个实体之间创建关系:用户和角色。

实体之间的关系表users_roles已成功生成，此外还生成了构成该表的两列id_user和id_role，也被添加到角色表中，我不确定这是否是预期的......

角色实体:

@Table(name = "role")
@Entity
public class Role extends AbstractEntity {

    private static final long serialVersionUID = 1L;

    public static final int PAPEL_USUARIO = 1;

    public static final int PAPEL_ADMIN = 2;

    public static final int PAPEL_PLANTONISTA = 3;

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "SEQ_ROLE")
    @SequenceGenerator(name = "SEQ_ROLE", sequenceName = "id_seq_role", allocationSize = 1)
    private Long id;

    @Column(name = "description", columnDefinition = "varchar(500)", nullable = true)
    private String description;

    @ManyToMany(mappedBy = "roles")
    private List<User> users;

    public Role() {

    }

    public Role(Long id) {
        this.id = id;
    }

    @Override
    public Long getId() {
        // TODO Auto-generated method stub
        return id;
    }

    @Override
    public void setId(Long id) {
        // TODO Auto-generated method stub
        this.id = id;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }
}

用户实体:

package br.ufrn.imd.hospital.entity;

import java.util.List;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.OneToOne;
import javax.persistence.SequenceGenerator;
import javax.persistence.Table;
import javax.validation.Valid;

@Table(name = "\"user\"")
@Entity
public class User extends AbstractEntity {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "SEQ_USER")
    @SequenceGenerator(name = "SEQ_USER", sequenceName = "seq_user", allocationSize = 1)
    private Long id;

    @Valid
    @OneToOne(cascade= {CascadeType.MERGE,CascadeType.PERSIST})
    private Person person;

    @ManyToMany
    @JoinTable(name = "users_roles", joinColumns = @JoinColumn(name = "id_user", referencedColumnName = "id"), inverseJoinColumns = @JoinColumn(name = "id_role", referencedColumnName = "id"))
    private List<Role> roles;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public Person getPerson() {
        return person;
    }

    public void setPerson(Person person) {
        this.person = person;
    }

    public List<Role> getRoles() {
        return roles;
    }

    public void setRoles(List<Role> roles) {
        this.roles = roles;
    }
}

Answer 1

这是预期的行为

@JoinTable(name = "users_roles", joinColumns = @JoinColumn(name = "id_user", referencedColumnName = "id"), inverseJoinColumns = @JoinColumn(name = "id_role", referencedColumnName = "id"))

这表明我们正在创建新的连接表，它将连接来自用户表的 id_user 和角色表的 id_role 映射的 2 个表中的两列

您可以查看

https://docs.jboss.org/hibernate/jpa/2.1/api/javax/persistence/JoinTable.html