JavaPersistenceWithHibernate第二版笔记-第五章-Mapping value types-002使用@Embeddable

一、数据库

二、代码

1.

package org.jpwh.model.simple;

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

/**
 * 
 * Instead of <code>@Entity</code>, this component POJO is marked with <code>@Embeddable</code>. It
 * has no identifier property.
 */
@Embeddable
public class Address {

    @NotNull // Ignored for DDL generation!
    @Column(nullable = false) // Used for DDL generation!
    protected String street;

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

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

    /**
     * Hibernate will call this no-argument constructor to create an instance, and then
     * populate the fields directly.
     */
    protected Address() {
    }

    /**
     * You can have additional (public) constructors for convenience.
     */
    public Address(String street, String zipcode, String city) {
        this.street = street;
        this.zipcode = zipcode;
        this.city = city;
    }

    public String getStreet() {
        return street;
    }

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

    public String getZipcode() {
        return zipcode;
    }

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

    public String getCity() {
        return city;
    }

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

You should override the equals() and hashCode() methods of Address and compare instances by value.

2.

package org.jpwh.model.simple;

import org.jpwh.model.Constants;

import javax.persistence.AttributeOverride;
import javax.persistence.AttributeOverrides;
import javax.persistence.Column;
import javax.persistence.Embedded;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;
import java.io.Serializable;
import java.math.BigDecimal;

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

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

    public Long getId() {
        return id;
    }

    protected String username;

    public User() {
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    // The Address is @Embeddable, no annotation needed here...
    protected Address homeAddress;

    public Address getHomeAddress() {
        return homeAddress;
    }

    public void setHomeAddress(Address homeAddress) {
        this.homeAddress = homeAddress;
    }

    @Embedded // Not necessary...
    @AttributeOverrides({
            @AttributeOverride(name = "street",
                    column = @Column(name = "BILLING_STREET")), // NULLable!
            @AttributeOverride(name = "zipcode",
                    column = @Column(name = "BILLING_ZIPCODE", length = 5)),
            @AttributeOverride(name = "city",
                    column = @Column(name = "BILLING_CITY"))
    })
    protected Address billingAddress;

    public Address getBillingAddress() {
        return billingAddress;
    }

    public void setBillingAddress(Address billingAddress) {
        this.billingAddress = billingAddress;
    }

    public BigDecimal calcShippingCosts(Address fromLocation) {
        // Empty implementation of business method
        return null;
    }

    // ...
}

3.

三、