JPA Create/Update 前修改 Entity (@PrePersist/@PreUpdate)

常常我們需要再寫入資料庫前,固定寫入某寫欄位 例如 創建日期 更新日期

原本操作方式

Model - Account.java ```java= import lombok.Data; import javax.persistence.*;

@Data @Entity public class Account implements Serializable { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private long id; private String username; private String password; private Date createAt; private Date updateAt;
}

Service - AccountService.java
```java=
public class AccountService {

    ...
    public Account createAccount(String user,String pass){
        Account a = new Account();
        ...
        Date nowAt = CommUtils.nowUtc0();
        a.setCreateAt(nowAt);
        a.setUpdateAt(nowAt);
        return dao.save(om);
    }

} 

改成 @PrePersist/@PreUpdate 去寫

創建一個新的

ModelAopService.java ```java=

public class ModelAopService {

...
@PrePersist
protected void onCreate(Account i) {
    Date now = CommUtils.nowUtc0();
    i.setCreateAt(now);
    i.setUpdateAt(now);
    i.setEnvProfile(springProfiles);
}

@PreUpdate
protected void onUpdate(Account i) {
    i.setUpdateAt(new Date());
}

}

將原本的 Service - AccountService.java
```java=
public class AccountService {

    ...
    public Account createAccount(String user,String pass){
        Account a = new Account();
        ...
        return dao.save(om);
    }

} 

這樣就可以把固定的寫入code 搬過去了

如果有多個Model都有這個屬性

此寫法也有支援多型

改法如下 先創建 CreateUpdateInfo.java interface

```java= public interface CreateUpdateInfo {

public Date getUpdateAt() ;

public void setUpdateAt(Date updateAt);

public Date getCreateAt() ;

public void setCreateAt(Date createAt) ;

}

 Model - Account.java impl CreateUpdateInfo
```java=
@Data
@Entity
public class Account implements Serializable,CreateUpdateInfo {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    private String username;
    private String password;
    private Date createAt;
    private Date updateAt;    
}    

將 ModelAopService.java 改為 ```java=

public class ModelAopService {

...
@PrePersist
protected void onCreate(CreateUpdateInfo i) {
    Date now = CommUtils.nowUtc0();
    i.setCreateAt(now);
    i.setUpdateAt(now);
    i.setEnvProfile(springProfiles);
}

@PreUpdate
protected void onUpdate(CreateUpdateInfo i) {
    i.setUpdateAt(new Date());
}

} ```

之後只要實作CreateUpdateInfo 就會寫入必要資訊