【hibernate】映射可嵌入式组件

【hibernate】映射可嵌入式组件

转载：https://www.cnblogs.com/yangchongxing/p/10376452.html

可嵌入 Address 类，没有对应的数据表

package cn.ycx.study.hibernate.entity;
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
    @Column(nullable=false)
    protected String zipcode;
    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;
    }
}

1、映射可嵌入组件

package cn.ycx.study.hibernate.entity;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
@Entity
@org.hibernate.annotations.DynamicInsert
@org.hibernate.annotations.DynamicUpdate
public class User {
    @Id
    @GeneratedValue(generator="id_generator")
    protected long id;
    protected String username;
    //嵌入式组件
    protected Address address;
    public long getId() {
        return id;
    }
    public void setId(long id) {
        this.id = id;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public Address getAddress() {
        return address;
    }
    public void setAddress(Address address) {
        this.address = address;
    }
}

产生的数据库表

CREATE TABLE `user` (
    `id` BIGINT(20) NOT NULL,
    `street` VARCHAR(255) NOT NULL,
    `zipcode` VARCHAR(255) NOT NULL,
    `username` VARCHAR(255) NULL DEFAULT NULL,
    PRIMARY KEY (`id`)
)
COLLATE='utf8mb4_general_ci'
ENGINE=InnoDB
;

2、重写映射可嵌入组件

package cn.ycx.study.hibernate.entity;

import javax.persistence.AttributeOverride;
import javax.persistence.AttributeOverrides;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
@Entity
@org.hibernate.annotations.DynamicInsert
@org.hibernate.annotations.DynamicUpdate
public class User {
    @Id
    @GeneratedValue(generator="id_generator")
    protected long id;
    protected String username;
    //嵌入式组件
    protected Address address;
    @AttributeOverrides({
        @AttributeOverride(
            name = "street",
            column = @Column(name = "order_street")
        ),
        @AttributeOverride(
            name = "zipcode",
            column = @Column(name = "order_zipcode")
        )
    })
    protected Address orderAddress;
    public long getId() {
        return id;
    }
    public void setId(long id) {
        this.id = id;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public Address getAddress() {
        return address;
    }
    public void setAddress(Address address) {
        this.address = address;
    }
    public Address getOrderAddress() {
        return orderAddress;
    }
    public void setOrderAddress(Address orderAddress) {
        this.orderAddress = orderAddress;
    }
}

产生的数据库表

CREATE TABLE `user` (
    `id` BIGINT(20) NOT NULL,
    `street` VARCHAR(255) NOT NULL,
    `zipcode` VARCHAR(255) NOT NULL,
    `order_street` VARCHAR(255) NULL DEFAULT NULL,
    `order_zipcode` VARCHAR(255) NULL DEFAULT NULL,
    `username` VARCHAR(255) NULL DEFAULT NULL,
    PRIMARY KEY (`id`)
)
COLLATE='utf8mb4_general_ci'
ENGINE=InnoDB
;

3、映射嵌套的可嵌入组件

可嵌入 Address 类中嵌套 City 类

package cn.ycx.study.hibernate.entity;
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
    @Column(nullable=false)
    protected String zipcode;
    public String getStreet() {
        return street;
    }
    @NotNull
    protected City city;

    public void setStreet(String street) {
        this.street = street;
    }
    public String getZipcode() {
        return zipcode;
    }
    public void setZipcode(String zipcode) {
        this.zipcode = zipcode;
    }
    public City getCity() {
        return city;
    }
    public void setCity(City city) {
        this.city = city;
    }
}

嵌套 City 类

package cn.ycx.study.hibernate.entity;

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

@Embeddable
public class City {
    @NotNull
    @Column(nullable=false)
    protected String country;

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

    public String getCountry() {
        return country;
    }
    public void setCountry(String country) {
        this.country = country;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
}

用户表

package cn.ycx.study.hibernate.entity;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
@Entity
@org.hibernate.annotations.DynamicInsert
@org.hibernate.annotations.DynamicUpdate
public class User {
    @Id
    @GeneratedValue(generator="id_generator")
    protected long id;
    protected String username;
    //可嵌入式组件
    protected Address address;
    public long getId() {
        return id;
    }
    public void setId(long id) {
        this.id = id;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public Address getAddress() {
        return address;
    }
    public void setAddress(Address address) {
        this.address = address;
    }
}

产生的数据库表

CREATE TABLE `user` (
    `id` BIGINT(20) NOT NULL,
    `country` VARCHAR(255) NOT NULL,
    `name` VARCHAR(255) NOT NULL,
    `street` VARCHAR(255) NOT NULL,
    `zipcode` VARCHAR(255) NOT NULL,
    `username` VARCHAR(255) NULL DEFAULT NULL,
    PRIMARY KEY (`id`)
)
COLLATE='utf8mb4_general_ci'
ENGINE=InnoDB
;

 这种嵌套关系理论上是可以嵌套无数层