If underlying database support UUID type, then Hibernate maps the property to SQL type UUID. If underlying database do not have UUID type, then it is mapped to JDBC BINARY type.
Can I store UUID in character representation?
Yes, you can store the UUID in character representation. For the efficient column storage reasons, Hibernate use binary representation by default. To switch this to char, set the hibernate.type.preferred_uuid_jdbc_type configuration to CHAR.
Find the below working application.
Step 1: Create new maven project ‘hibernate-uuid-mapping’.
Step 2: Update pom.xml with maven dependencies.
pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.sample.app</groupId>
<artifactId>hibernate-uuid-mapping</artifactId>
<version>1</version>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<java.version>15</java.version>
<maven.compiler.source>${java.version}</maven.compiler.source>
<maven.compiler.target>${java.version}</maven.compiler.target>
</properties>
<dependencies>
<!-- <dependency> <groupId>com.h2database</groupId> <artifactId>h2</artifactId>
<version>2.1.214</version> </dependency> -->
<dependency>
<groupId>org.postgresql</groupId>
<artifactId>postgresql</artifactId>
<version>42.4.1</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>6.1.2.Final</version>
</dependency>
<dependency>
<groupId>javax.persistence</groupId>
<artifactId>javax.persistence-api</artifactId>
<version>2.2</version>
</dependency>
</dependencies>
</project>
Step 3: Define Employee entity class.
Employee.java
package com.sample.app.entity;
import java.util.Locale;
import java.util.UUID;
import jakarta.persistence.Entity;
import jakarta.persistence.Id;
import jakarta.persistence.Table;
@Entity
@Table(name = "employees")
public class Employee {
@Id
private UUID id;
private String name;
private Locale userLocale;
public Employee(UUID id, String name, Locale userLocale) {
this.id = id;
this.name = name;
this.userLocale = userLocale;
}
public UUID getId() {
return id;
}
public void setId(UUID id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Locale getUserLocale() {
return userLocale;
}
public void setUserLocale(Locale userLocale) {
this.userLocale = userLocale;
}
@Override
public String toString() {
return "Employee [id=" + id + ", name=" + name + ", userLocale=" + userLocale + "]";
}
}
Step 4: Create hibernate.cfg.xml file under src/main/resources folder.
hibernate.cfg.xml
<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<!-- Database Connection settings -->
<property name="connection.driver_class">org.postgresql.Driver</property>
<property name="connection.url">jdbc:postgresql://127.0.0.1:5432/test</property>
<property name="connection.username">postgres</property>
<property name="connection.password">postgres</property>
<!-- Enable the logging of all the generated SQL statements to the console -->
<property name="show_sql">true</property>
<!-- Format the generated SQL statement to make it more readable, -->
<property name="format_sql">true</property>
<!-- Hibernate will put comments inside all generated SQL statements to
hint what’s the generated SQL trying to do -->
<property name="use_sql_comments">false</property>
<property name="dialect">org.hibernate.dialect.PostgreSQLDialect</property>
<property name="hbm2ddl.auto">update</property>
<!-- mappings for annotated classes -->
<mapping class="com.sample.app.entity.Employee" />
</session-factory>
</hibernate-configuration>
Step 5: Define main application class.
App.java
package com.sample.app;
import java.io.IOException;
import java.net.URISyntaxException;
import java.util.List;
import java.util.Locale;
import java.util.UUID;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.boot.Metadata;
import org.hibernate.boot.MetadataSources;
import org.hibernate.boot.registry.StandardServiceRegistry;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import com.sample.app.entity.Employee;
import jakarta.persistence.criteria.CriteriaBuilder;
import jakarta.persistence.criteria.CriteriaQuery;
public class App {
private static SessionFactory sessionFactory = buildSessionFactory();
private static <T> List<T> loadAllData(Class<T> clazz, Session session) {
final CriteriaBuilder builder = session.getCriteriaBuilder();
final CriteriaQuery<T> criteria = builder.createQuery(clazz);
criteria.from(clazz);
return session.createQuery(criteria).getResultList();
}
private static SessionFactory buildSessionFactory() {
try {
if (sessionFactory == null) {
StandardServiceRegistry standardRegistry = new StandardServiceRegistryBuilder()
.configure("hibernate.cfg.xml").build();
Metadata metaData = new MetadataSources(standardRegistry).getMetadataBuilder().build();
sessionFactory = metaData.getSessionFactoryBuilder().build();
}
return sessionFactory;
} catch (Throwable ex) {
throw new ExceptionInInitializerError(ex);
}
}
public static void main(String args[]) throws ClassNotFoundException, IOException, URISyntaxException {
Employee emp = new Employee(UUID.randomUUID(), "Krishna", Locale.ENGLISH);
try (Session session = sessionFactory.openSession()) {
session.beginTransaction();
session.persist(emp);
session.flush();
session.getTransaction().commit();
List<Employee> emps = loadAllData(Employee.class, session);
for (Employee emp1 : emps) {
System.out.println(emp1);
}
}
}
}
Total project structure looks like below.
Run App.java, you will see below messages in the console.
Aug 18, 2022 4:05:59 PM org.hibernate.Version logVersion
INFO: HHH000412: Hibernate ORM core version 6.1.2.Final
Aug 18, 2022 4:06:00 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl configure
WARN: HHH10001002: Using built-in connection pool (not intended for production use)
Aug 18, 2022 4:06:00 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH10001005: Loaded JDBC driver class: org.postgresql.Driver
Aug 18, 2022 4:06:00 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH10001012: Connecting with JDBC URL [jdbc:postgresql://127.0.0.1:5432/test]
Aug 18, 2022 4:06:00 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH10001001: Connection properties: {password=****, user=postgres}
Aug 18, 2022 4:06:00 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH10001003: Autocommit mode: false
Aug 18, 2022 4:06:00 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl$PooledConnections <init>
INFO: HHH10001115: Connection pool size: 20 (min=1)
Aug 18, 2022 4:06:00 PM org.hibernate.engine.jdbc.dialect.internal.DialectFactoryImpl logSelectedDialect
INFO: HHH000400: Using dialect: org.hibernate.dialect.PostgreSQLDialect
Aug 18, 2022 4:06:00 PM org.hibernate.metamodel.internal.EntityInstantiatorPojoStandard resolveConstructor
INFO: HHH000182: No default (no-argument) constructor for class: com.sample.app.entity.Employee (class must be instantiated by Interceptor)
Aug 18, 2022 4:06:00 PM org.hibernate.resource.transaction.backend.jdbc.internal.DdlTransactionIsolatorNonJtaImpl getIsolatedConnection
INFO: HHH10001501: Connection obtained from JdbcConnectionAccess [org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator$ConnectionProviderJdbcConnectionAccess@7847ef2c] for (non-JTA) DDL execution was not in auto-commit mode; the Connection 'local transaction' will be committed and the Connection will be set into auto-commit mode.
Hibernate:
create table employees (
id uuid not null,
name varchar(255),
userLocale varchar(255),
primary key (id)
)
Aug 18, 2022 4:06:00 PM org.hibernate.engine.transaction.jta.platform.internal.JtaPlatformInitiator initiateService
INFO: HHH000490: Using JtaPlatform implementation: [org.hibernate.engine.transaction.jta.platform.internal.NoJtaPlatform]
Hibernate:
insert
into
employees
(name, userLocale, id)
values
(?, ?, ?)
Hibernate:
select
e1_0.id,
e1_0.name,
e1_0.userLocale
from
employees e1_0
Employee [id=27beafcf-65f5-461b-8a73-b08074abcf10, name=Krishna, userLocale=en]
Confirm the same by querying PostgreSQL.
test=# \d+ employees;
Table "public.employees"
Column | Type | Collation | Nullable | Default | Storage | Compression | Stats target | Description
------------+------------------------+-----------+----------+---------+----------+-------------+--------------+-------------
id | uuid | | not null | | plain | | |
name | character varying(255) | | | | extended | | |
userlocale | character varying(255) | | | | extended | | |
Indexes:
"employees_pkey" PRIMARY KEY, btree (id)
Access method: heap
test=#
test=#
test=# SELECT * FROM employees;
id | name | userlocale
--------------------------------------+---------+------------
27beafcf-65f5-461b-8a73-b08074abcf10 | Krishna | en
You can download this application from this link.
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