Hibernate读书笔记--@embed的理解

@Embedded英文意思就是固定的。

按照这个理解其实就是一个宽表中的部分字段组成的类。

如

@Entity
@Table(name = "USERS")
public class User {
...
@Embedded
private Address homeAddress;
...
}

 而本身Address的类

@Embeddable
public class Address {
@Column(name = "ADDRESS_STREET", nullable = false)
private String street;
@Column(name = "ADDRESS_ZIPCODE", nullable = false)
private String zipcode;
@Column(name = "ADDRESS_CITY", nullable = false)
private String city;
...
}

 这样user表中自动加入了address的几个字段

有什么用？

如果Order订单中也有地址，按照设计原则应当采用相同的字段

@Entity
@Table(name = "Orders")
public class Orders{
...
@Embedded
private Address orderAddress;
...
}

 这样order中也有了。