springboot jpa 非主键连接

1. 问题

springboot jpa连接mysql，两个表通过主键管理则不需要额外做一些配置，但是遇到非主键关联时则需要修改

2. 具体代码

@Entity
@Data
@Table
@AllArgsConstructor
@NoArgsConstructor
public class Friend implements Serializable {
    /**
     * 主键
     */
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Id
    private Long id;

    /**
     * 聊天号
     */
    @ManyToOne(cascade=CascadeType.PERSIST,fetch=FetchType.EAGER)
    @JoinColumn(name="selfMessageNumber",referencedColumnName = "messageNumber")
    private Member selfMessageNumber;

    /**
     * 聊天号
     */
    @ManyToOne(cascade=CascadeType.PERSIST,fetch=FetchType.EAGER)
    @JoinColumn(name="partnerMessageNumber",referencedColumnName = "messageNumber")
    private Member partnerMessageNumber;

    /**
     * 群组号
     */
    @ManyToOne
    @JoinColumn(name="group_id",referencedColumnName = "id")
    private FriendGroup friendGroup;

    /**
     * 0自增加1非自增加
     */
    @Enumerated(EnumType.ORDINAL)
    private AddFlagEnum addFlag;

    /**
     * 0未删除1已删除
     */
    private Integer deleteFlag;

    /**
     * 添加时间
     */
    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")
    private LocalDateTime insertTime;

    /**
     * 修改时间
     */
    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")
    private LocalDateTime updateTime;

    /**
     * 备注
     */
    private String remark;

}

@Entity
@Data
@Table
@AllArgsConstructor
@NoArgsConstructor
public class Friend implements Serializable {
    /**
     * 主键
     */
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Id
    private Long id;

    /**
     * 聊天号
     */
    @ManyToOne(cascade=CascadeType.PERSIST,fetch=FetchType.EAGER)
    @JoinColumn(name="selfMessageNumber",referencedColumnName = "messageNumber")
    private Member selfMessageNumber;

    /**
     * 聊天号
     */
    @ManyToOne(cascade=CascadeType.PERSIST,fetch=FetchType.EAGER)
    @JoinColumn(name="partnerMessageNumber",referencedColumnName = "messageNumber")
    private Member partnerMessageNumber;

    /**
     * 群组号
     */
    @ManyToOne
    @JoinColumn(name="group_id",referencedColumnName = "id")
    private FriendGroup friendGroup;

    /**
     * 0自增加1非自增加
     */
    @Enumerated(EnumType.ORDINAL)
    private AddFlagEnum addFlag;

    /**
     * 0未删除1已删除
     */
    private Integer deleteFlag;

    /**
     * 添加时间
     */
    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")
    private LocalDateTime insertTime;

    /**
     * 修改时间
     */
    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")
    private LocalDateTime updateTime;

    /**
     * 备注
     */
    private String remark;

}

3.解决方式

1. 请注意Friend实体类的selfMessageNumber、partnerMessageNumber属性，@JoinColumn(name="selfMessageNumber",referencedColumnName = "messageNumber")这个注解就是Friend的selfMessageNumber->Member的messageNumber，以此指定关联
2. 实体类必须implements Serializable ，实体类必须implements Serializable ，实体类必须implements Serializable 重要的事情说三遍