@MappedSuperclass和实现表

Question

我继承了一些非常糟糕的代码，我希望通过重构来提高可重用性。有一组报告表，主要由3列组成：id、report_type_fk和report_description。为了便于使用，我想把所有的报告表合并成一个。

我正在重构代码，并认为最好将当前实体分解，以便Report是一个具有type实现的抽象类。例如，DmvReport extends Report、CreditScoreReport extends Report等。

我遇到的问题是，只有一个报告表需要保存到所有实体。是否有办法将abstract Report对象的所有具体实现保存到同一个表中？

下面是我继承的坏代码的一个例子

报告类

@Entity
@Table(name = "report")
public class Report<E extends Exception> {
    private long id;
    private ReportType type;
    private String description;
   ...
   ...
}

CreditReport类

@Entity
@Table(name = "credit_report")
public class CreditScore Report<E extends Exception> extends Report<E> {
    private long id;
    private ReportType type;
    private String description;
   ...
   ...
}

我想把它变成：

@MappedSuperclass
@Table(name = "report")
public abstract class Report<E extends Exception> {
    @Id @Column(name="id")
    private long id;

    @OneToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "report_type_id")
    private ReportType type;

    @column(name="description")
    private String description;
   ...
   ...
}

@Entity
@Table(name = "report")
public class CreditScoreReport<E extends Exception> extends Report<E> {

   public void doCreditScoreStuff(){
      ...
   }
}

@Entity
@Table(name = "report")
public class DmvReport<E extends Exception> extends Report<E> {
   public void doDmvStuff(){
      ...
   }
}

Answer 1

我认为您应该使用@Inheritance而不是@MappedSuperClass。您的代码将如下所示：

@Entity
@Table(name = "report")
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name = "report_type_id", discriminatorType = DiscriminatorType.INTEGER)
public abstract class Report<E extends Exception> {
    @Id @Column(name="id")
    private long id;

    @column(name="description")
    private String description;
   ...
   ...
}

@Entity(name = "CreditScoreReport")
@DiscriminatorValue("1") // the id corresponding to the credit score report
public class CreditScoreReport<E extends Exception> extends Report<E> {

   @Column(name = "specific_credit_score_report_1)
   private Integer specificCreditScoreReport1;

   public void doCreditScoreStuff(){
      ...
   }
}

@Entity(name = "DmvReport")
@DiscriminatorValue("2") // the id corresponding to the DMV report
public class DmvReport<E extends Exception> extends Report<E> {

   @Column(name = "specific_dmv_score_report_1)
   private Integer specificDmvScoreReport1;

   public void doDmvStuff(){
      ...
   }
}

此策略允许您将信用评分报告和DMV报表数据存储在一个表(report)中，但可以根据report_value_id字段实例化适当的实体。您不必在参数中定义report_value_id，因为它已经用于创建所需的实体。

这就是你要找的吗？