java JPA使用嵌套类中的id

Question

我的数据库中有一个表

create table metrics
(
    metric_id   integer,
    time        timestamp,
    workflow_id varchar,
    job_id      varchar,
    name        varchar,
    metric_type   varchar
);

和两个物体

@Embeddable
public class Metric {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long metricId;
    private OffsetDateTime time;
    private String workflowId;
    private String jobId;
    private String name;
}

@Entity
@Table(name = "metrics")
public class CPU {
    @Enumerated(EnumType.STRING)
    private final MetricType metricType = MetricType.CPU;
    @Embedded
    private Metric metric;
}

是否可以使用Metric类中定义的@Id作为@Id用于CPU实体
我不想创建复合键，我只想使用来自Metric的@Id作为CPU中的@Id

Answer 1

似乎您想要使用的是基于鉴别器的继承：

@Entity
@Table(name = "metrics")
@DiscriminatorColumn(name = "metric_type")
public abstract class Metric {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long metricId;
    private OffsetDateTime time;
    private String workflowId;
    private String jobId;
    private String name;
}

@Entity
@DiscriminatorValue("CPU")
public class CPU extends Metric {
}