JPA：如何覆盖@Embedded 属性的列名

Question

Person类

@Embeddable
public class Person {
    @Column
    public int code;

    //...
}

在 Event 中嵌入了两个不同的属性：manager 和 operator

@Entity
public class Event {
    @Embedded
    @Column(name = "manager_code")
    public Person manager;

    @Embedded
    @Column(name = "operator_code")
    public Person operator;

    //...
}

当使用 Persistence 生成数据库模式时，这应该给出两个相应的列。而是抛出异常：

org.hibernate.MappingException：实体映射中的重复列：事件列：代码

如何覆盖每个属性的默认列名code？

Answer 1

使用@AttributeOverride，这里是一个例子

@Embeddable public class Address {
    protected String street;
    protected String city;
    protected String state;
    @Embedded protected Zipcode zipcode;
}

@Embeddable public class Zipcode {
    protected String zip;
    protected String plusFour;
}

@Entity public class Customer {
    @Id protected Integer id;
    protected String name;
    @AttributeOverrides({
        @AttributeOverride(name="state",
                           column=@Column(name="ADDR_STATE")),
        @AttributeOverride(name="zipcode.zip",
                           column=@Column(name="ADDR_ZIP"))
    })
    @Embedded protected Address address;
    ...
}

在你的情况下，它看起来像这样

@Entity
public class Event {
    @Embedded
    @AttributeOverride(name="code", column=@Column(name="manager_code"))
    public Person manager;

    @Embedded
    @AttributeOverride(name="code", column=@Column(name="operator_code"))
    public Person operator;

    //...
}