为什么在使用 JPA 映射类时应该在 getter 或 setter 上添加注释? [英] Why should anybody put annotations on the getters or setters when using JPA to map the classes?
问题描述
主题说明了一切......到目前为止,我认为人们在 getter 和/或 setter 上声明注释没有任何好处.对我来说,这唯一的缺点是将注释散布在类上,这会使类更不可读.
Subject says it all... I see no advantage of people declaring annotations on the getters and/or setters so far. For me this only has the disadvantage of spreading the annotations over the class, which can make the class more unreadable.
将注释放在字段上显然可以减少需要帮助时发布的代码量.但这只是一个很小的优势.但是在方法上添加注释对我来说没有任何意义.
Putting the annotations on the fields clearly reduces the amount of code to post when needing help. This is just a tiny advantage though. But putting annotations on methods would serve no purpose to me.
推荐答案
在方法上添加注解会强制 JPA 通过方法访问属性.当对象的内部状态与数据库架构不同时,这是有道理的:
Putting annotations on methods forces JPA to access properties via methods. It makes sense when internal state of your object differs from the database schema:
@Entity
public class Employee {
private String firstName;
private String lastName;
@Column(name = "EMP_NAME") // Due to legacy database schema
public String getName() {
return fisrtName + " " + lastName;
}
public void setName(String name) {
...
}
... Getters and setters for firstName and lastName with @Transient ...
}
在 JPA 2.0 中,您可以使用 @Access
在细粒度级别指定访问类型:
In JPA 2.0 you can specify access type at fine-grained level with @Access
:
@Entity @Access(AccessType.FIELD)
public class Employee {
@Access(AccessType.PROPERTY) @Column(name = "EMP_NAME")
public String getName() { ... }
... other properties have field access ...
}
这篇关于为什么在使用 JPA 映射类时应该在 getter 或 setter 上添加注释?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!