JavaPersistenceWithHibernate第二版笔记-第五章-Mapping value types-004嵌套组件的注解AttributeOverrides

一、数据库

二、代码

1.

package org.jpwh.model.advanced;

import javax.persistence.AttributeOverride;
import javax.persistence.AttributeOverrides;
import javax.persistence.Column;
import javax.persistence.Embeddable;
import javax.validation.constraints.NotNull;

@Embeddable
public class Address {

    @NotNull
    @Column(nullable = false)
    protected String street;

    @NotNull
    @AttributeOverrides(
        @AttributeOverride(
            name = "name",
            column = @Column(name = "CITY", nullable = false)
        )
    )
    protected City city;

    public String getStreet() {
        return street;
    }

    public void setStreet(String street) {
        this.street = street;
    }

    public City getCity() {
        return city;
    }

    public void setCity(City city) {
        this.city = city;
    }

    // ...
}

2.

package org.jpwh.model.advanced;

import javax.persistence.Column;
import javax.persistence.Embeddable;
import javax.validation.constraints.NotNull;

@Embeddable
public class City {

    @NotNull
    @Column(nullable = false, length = 5) // Override VARCHAR(255)
    protected String zipcode;

    @NotNull
    @Column(nullable =  false)
    protected String name;

    @NotNull
    @Column(nullable =  false)
    protected String country;

    public String getZipcode() {
        return zipcode;
    }

    public void setZipcode(String zipcode) {
        this.zipcode = zipcode;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getCountry() {
        return country;
    }

    public void setCountry(String country) {
        this.country = country;
    }

    // ...
}

3.

package org.jpwh.model.advanced;

import org.jpwh.model.Constants;

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

@Entity
@Table(name = "USERS")
public class User {

    @Id
    @GeneratedValue(generator = Constants.ID_GENERATOR)
    protected Long id;

    public Long getId() {
        return id;
    }

    protected Address address;

    public Address getAddress() {
        return address;
    }

    public void setAddress(Address address) {
        this.address = address;
    }
}

You can declare @AttributeOverride s at any level, as you do for the name property of the City class, mapping it to the CITY column. This can be achieved with either (as shown) an @AttributeOverride in Address or an override in the root entity class,User . Nested properties can be referenced with dot notation: for example, on User#address , @AttributeOveride(name = "city.name") references the Address #City#name attribute.