JPA中Id的默認長度

Question

如何將JPA中Id的默認值設置爲38？我知道我可以使用@Column（length = 38）設置單個ID長度，但是如何在全局中更改它？

如果這對於JPA來說是不可能的，也許是Spring Data或Hibernate？

Answer 1

我想你應該添加一個抽象父類的實體，這是我AbstractEntity：

@MappedSuperclass 
public class AbstractEntity { 

    @Id 
    @GeneratedValue 
    @Column(length=38) 
    private Long id; 

    @Column(name = "created_at") 
    private Date createdTime; 

    @Column(name = "updated_at") 
    private Date updatedTime; 

    @PrePersist 
    public void init() { 
     if(createdTime == null) { 
      createdTime = new Date(); 
     } 
     updatedTime = new Date(); 
    } 

    public Long getId() { 
     return id; 
    } 

    public void setId(Long id) { 
     this.id = id; 
    } 

    public Date getCreatedTime() { 
     return createdTime; 
    } 

    public void setCreatedTime(Date createdTime) { 
     this.createdTime = createdTime; 
    } 

    public Date getUpdatedTime() { 
     return updatedTime; 
    } 

    public void setUpdatedTime(Date updatedTime) { 
     this.updatedTime = updatedTime; 
    } 


}