Hibernate :如何覆盖映射超类中的属性
Hibernate :如何覆盖映射超类中的属性
提问于 2011-03-10 17:51:53
泛型实体，超类：
@MappedSuperclass
public abstract class GenericEntity {
private Integer id;
public Integer getId() {return id;}
public void setId(Integer id) {this.id = id;}
}pojo：
@Entity
@Table(name = "POJO_ONE")
@SequenceGenerator(name = "HB_SEQ_POJO_ONE", sequenceName = "SEQ_POJO_ONE", allocationSize = 1)
public class PojoOne extends GenericEntity {
@Id
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "HB_SEQ_POJO_ONE")
@Column(name = "ID")
@AttributeOverride(name = "id", column = @Column(name = "ID"))
private Integer id;
@Override
public Integer getId() {return id;}
}我尝试使用这些注释：@AttributeOverride，@Id，...但它不起作用。你能帮帮我吗?我想通过覆盖属性"id“来指定另一个列名和pojo/table的序列。做到这一点的最好方法是什么？
回答 2
Stack Overflow用户
回答已采纳
发布于 2011-03-10 18:05:32
试试这个吧。
@MappedSuperclass
public abstract class GenericEntity {
protected Integer id;
...
public Integer getId() {return id;}
public void setId(Integer id) {this.id = id;}
}
@Entity
@Table(name = "POJO_ONE")
@SequenceGenerator(name = "HB_SEQ_POJO_ONE", sequenceName = "SEQ_POJO_ONE", allocationSize = 1)
@AttributeOverride(name = "id", column = @Column(name = "ID"))
public class PojoOne extends GenericEntity {
// we should not define id here again
...
@Override
@Id
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "HB_SEQ_POJO_ONE")
public Integer getId() {return id;}
}Stack Overflow用户
发布于 2011-03-10 18:01:05
为什么不用@Id注释GenericEntity的id呢？您也不应该重新定义id，而是将@AttributeOverride(name = "id", column = @Column(name = "ID"))放在类上，而不是放在字段上。
编辑：
我们在基类中使用了这个(package.OurTableGenerator是我们自己的实现)：
@GeneratedValue ( generator = "ourTableGenerator", strategy = GenerationType.TABLE )
@GenericGenerator ( name = "ourTableGenerator", strategy = "package.OurTableGenerator",
parameters = { @Parameter ( name = OurTableGenerator.TABLE_PARAM, value = "t_sequence" ),
@Parameter ( name = OurTableGenerator.SEGMENT_COLUMN_PARAM, value = "c_entity" ),
@Parameter ( name = OurTableGenerator.VALUE_COLUMN_PARAM, value = "c_nextHi" ),
@Parameter ( name = OurTableGenerator.INCREMENT_SIZE_COLUMN_PARAM, value = "c_blocksize" ) } )
@Id
@Column(name = "c_uid")
private Long uid;这让我们为每个实体/表指定不同的块大小和顺序。
对于您自己的表生成器，您可以子类化org.hibernate.id.TableGenerator。
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原文链接：
https://stackoverflow.com/questions/5257921
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