我有一个问题，我有两个实体Job和JobPK
Job class looks like this sample code :
@Entity
@IdClass(JobPK.class)
@Table(name="JOB")
@Inheritance
@DiscriminatorColumn(name="JOB_TYPE")
public abstract class Job implements Serializable {
@Id
@Column(name="FOLDER_ID")
private BigDecimal folderId;
@Id
@ColumnDefinition(position = 1)
private String name;
@Column(name="JOB_TYPE",insertable=false,updatable=false)
private String jobType;
...
}
和JobPk：
public class JobPK implements Serializable {
private static final long serialVersionUID = -3266336718203527905L;
@Column(name="JOB_TYPE",insertable=false,updatable=false)
private String jobType;
@Id
private String name;
@Id
@Column(name="FOLDER_ID")
private BigDecimal folderId;
......
}
我有两个扩展Job的类：CalculatingJob和ImportingJob
现在我不会使用：
getEntityManager().find(CalculatingJob.class, new JobPK (BigDecimal.valueOf(folderId),name))
我有问题，因为我必须填写JobPK描述符值字段。如果我不这样做，我会得到Null Pointer Exception。我认为默认情况下，描述符值是关键，但我不希望在JobPk创建期间放置有关描述符值的信息。我认为从Job扩展的Entity会自动填充此字段。任何绕过此问题的想法，也许我都可以从CalculatingJob获取Annotation @DescriminatorVale，然后放入构造函数JobPk中
感谢帮助
最佳答案
尝试此配置用于层次结构
Job.java
@Table(name = "JOB")
@Inheritance
@IdClass(JobPK.class)
@DiscriminatorColumn(name = "JOB_TYPE", discriminatorType = DiscriminatorType.STRING)
public abstract class Job implements java.io.Serializable {
}
CalculatingJob.java
@Entity
@DiscriminatorValue("CalculatingJob")
public class CalculatingJob extends Job {
}
导入Job.java
@Entity
@DiscriminatorValue("ImportingJob")
public class ImportingJob extends Job {
}
JobPK.java
public class JobPK implements Serializable {
}
鉴别值是通过休眠输入的。