Question

我的Entity类有共同的属性。他们必须有 Id - 序列long号码 Date createdDate ，显示实体的元组何时添加到数据库和Date lastModifiedDate 属性，该属性显示何时完成最后一次修改一个元组。

我使用JPA 2.1。，Hibernate 4.3.6.Final

<depedencies>
    <!-- Hibernate -->
    <dependency>
        <groupId>org.hibernate.javax.persistence</groupId>
        <artifactId>hibernate-jpa-2.1-api</artifactId>
        <version>1.0.0.Final</version>
    </dependency>

    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-validator</artifactId>
        <version>5.1.1.Final</version>
    </dependency>

    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-entitymanager</artifactId>
        <version>4.3.6.Final</version>
    </dependency>

    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.34</version>
    </dependency>
 </dependencies>

所以我用关键属性创建了公共类：

@Embeddable
public class AbstractArticle implements Serializable {
private static final long serialVersionUID = 895868474989692116L;

@Nonnull
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(nullable = false)
private long id;

@Temporal(TemporalType.TIMESTAMP)
@Column(name = "createdDate", nullable = false)
private Date createdDate;

@Temporal(TemporalType.TIMESTAMP)
@Column(name = "lastModifiedDate", nullable = false)
private Date lastModifiedDate;

public AbstractArticle() {
}

... //getters and setters
}

和另一个使用此公共密钥值的类

@Entity
public class BBCNews{
@Nonnull
@Column(name = "newsId", nullable = false)
private long newsId;

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

@CheckForNull
@Column(name = "description", nullable = true)
private String description;

@Id
private AbstractArticle abstractArticle;

public BBCNews() {
}
...//getters and setters

确定一切正常，但长id AbstractArticle是相同的0，DB中的所有元组都是0作为id。这个的目的是什么呢？任何想法？

Answer 1

使用继承可能吗？

@MappedSuperclass
public abstract class AbstractArticle implements Serializable { /* ... */ }

@Entity
public class BBCNews extends AbstractArticle { /* ... */ }

如何使用JPA和Hibernate为实体分隔关键公共类？

1 个答案: