javax.persistence对field，getter或setter的注释？ [英] javax.persistence Annotations on field, getter or setter?

问题描述

我目前正在学习Hibernate和Java Persistence API。

I am currently learning Hibernate and the Java Persistence API.

我有一个@Entity类，需要对各个字段应用注释。我已经在下面的代码中包含了他们可以去的所有三个地方。

I have an @Entity class, and need to apply annotations to the various fields. I have included in the code below all three places where they could go.

我应该将它们应用到字段本身，getter还是setter？这三个选项之间的语义差异是什么（如果有的话）。

Should I apply them to the field itself, the getter or the setter? And what is the semantic difference, if any, between these three options.

import javax.persistence.Entity;
import javax.persistence.Table;
import javax.persistence.Id;

@Entity
@Table(name = "song")
public class Song { 
    // Annotations should only be applied to one of the below

    @Id 
    @Column(name="id", unique=true, nullable=false)
    private int    id;

    @Id
    @Column(name="id", unique=true, nullable=false)
    public int getId() {
        return id;
    }

    @Id
    @Column(name="id", unique=true, nullable=false)
    public void setId(int id) {
        this.id = id;
    }
}

推荐答案

你必须在场和吸气之间做出选择。不支持在setter上添加注释。并且所有注释都应该在字段上，或者它们都应该在getter上：你不能混合两种方法（除非你使用 @AccessType 注释）。

You have to choose between field and getter. Annotations on setters are not supported. And all the annotations should be on fields, or they should all be on getters: you can't mix both approaches (except if you use the @AccessType annotation).

关于哪一个更喜欢，答案是：它取决于。我更喜欢现场访问，但YMMV，并且有些情况下属性访问是可取的。请参阅 Hibernate Annotations - 哪个更好，字段或属性访问？。

Regarding which one is preferrale, the answer is: it depends. I prefer field access, but YMMV, and there are situations where property access is preferrable. See Hibernate Annotations - Which is better, field or property access?.

这篇关于javax.persistence对field，getter或setter的注释？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！