【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