CREATE TABLE `advert` ( `id` int(20) NOT NULL AUTO_INCREMENT COMMENT '主键', `name` varchar(100) COLLATE utf8mb4_bin NOT NULL COMMENT '广告名称', `position_id` int(20) NOT NULL COMMENT '广告位置ID', `media_id` int(20) NOT NULL COMMENT '广告图片ID', `link` varchar(500) COLLATE utf8mb4_bin NOT NULL COMMENT '广告链接', `status` int(1) unsigned zerofill NOT NULL COMMENT '状态,0：未启用，1：已启用，2：已结束', PRIMARY KEY (`id`) USING BTREE, KEY `FK_ad_image` (`media_id`), KEY `FK_ad_position` (`position_id`), CONSTRAINT `FK_ad_image` FOREIGN KEY (`media_id`) REFERENCES `media_file` (`id`) ON DELETE CASCADE ON UPDATE CASCADE, CONSTRAINT `FK_ad_position` FOREIGN KEY (`position_id`) REFERENCES `ad_position` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin COMMENT='广告表'; CREATE TABLE `ad_position` ( `id` int(20) NOT NULL AUTO_INCREMENT COMMENT '主键', `name` varchar(50) COLLATE utf8mb4_bin NOT NULL COMMENT '位置名称', PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin COMMENT='广告位置表'; CREATE TABLE `media_file` ( `id` int(20) NOT NULL AUTO_INCREMENT COMMENT '主键', `name` varchar(30) COLLATE utf8mb4_bin NOT NULL COMMENT '媒体文件名称', `type` tinyint(1) NOT NULL COMMENT '媒体文件类型：0-图片，1-视频', `url` varchar(500) COLLATE utf8mb4_bin NOT NULL COMMENT '媒体文件URL地址', PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin COMMENT='广告媒体文件表'; springboot项目用java写出三张表的orm对象（使用jpa外键依赖）

请看下面的代码：

Advert.java

@Entity
@Table(name = "advert")
public class Advert {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Integer id;

    @Column(name = "name", nullable = false)
    private String name;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "position_id")
    private AdPosition adPosition;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "media_id")
    private MediaFile mediaFile;

    @Column(name = "link", nullable = false)
    private String link;

    @Column(name = "status", nullable = false)
    private Integer status;

    // Getters and setters
}

AdPosition.java

@Entity
@Table(name = "ad_position")
public class AdPosition {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Integer id;

    @Column(name = "name", nullable = false)
    private String name;

    @OneToMany(mappedBy = "adPosition")
    private List<Advert> adverts;

    // Getters and setters
}

MediaFile.java

@Entity
@Table(name = "media_file")
public class MediaFile {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Integer id;

    @Column(name = "name", nullable = false)
    private String name;

    @Column(name = "type", nullable = false)
    private Integer type;

    @Column(name = "url", nullable = false)
    private String url;

    @OneToMany(mappedBy = "mediaFile")
    private List<Advert> adverts;

    // Getters and setters
}

这里使用了 JPA 的注解来定义实体类，并使用外键依赖。其中，Advert 实体类使用了 @ManyToOne 注解，表示多个广告对应一个广告位置和一个媒体文件；AdPosition 和 MediaFile 实体类使用了 @OneToMany 注解，表示一个广告位置和一个媒体文件对应多个广告。注意，AdPosition 和 MediaFile 实体类中的 adverts 属性需要使用 mappedBy 属性来指定关联属性名，以建立关联关系。