Embeddable Component Mapping

An Address class is defined as embeddable without a corresponding database table.

package com.example.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;
    }
}

Mapping an Embeddable Copmonent

package com.example.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;
    
    // Embedded component
    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;
    }
}

The resulting database schema:

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;

Overirding Column Names for Embeddable Components

package com.example.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;
    
    // Embedded component
    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;
    }
}

Resulting table schema:

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;

Nested Embeddable Components

The Address class includes a nested City component.

package com.example.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;
    
    @NotNull
    protected 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 City getCity() {
        return city;
    }
    
    public void setCity(City city) {
        this.city = city;
    }
}

The nested City component:

package com.example.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;
    }
}

User entity mapping:

package com.example.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;
    
    // Embedded component
    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;
    }
}

Generated table structure:

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;

Nested structures can theoretically be extended to any depth.