Hibernate @CreationTimestamp and @UpdateTimestamp Tutorial

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In this tutorial, we will create a simple example using Hibernate to demonstrate the use of @CreationTimestamp and @UpdateTimestamp annotations. These annotations are used to automatically populate timestamp fields for entity creation and updates.

Prerequisites

1. Java Development Kit (JDK) 21 or higher: Ensure JDK is installed and configured in your system.
2. Integrated Development Environment (IDE): IntelliJ IDEA, Eclipse, or any other IDE.
3. Maven: Ensure Maven is installed and configured in your system.

Step 1: Create a Maven Project

1. Open your IDE and create a new Maven project.
2. Update the pom.xml file to include Hibernate and other required dependencies.

<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 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.example</groupId> <artifactId>hibernate-timestamp-example</artifactId> <version>1.0-SNAPSHOT</version> <dependencies> <dependency> <groupId>org.hibernate.orm</groupId> <artifactId>hibernate-core</artifactId> <version>6.2.0.Final</version> </dependency> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-api</artifactId> <version>1.7.30</version> </dependency> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-simple</artifactId> <version>1.7.30</version> </dependency> <dependency> <groupId>com.h2database</groupId> <artifactId>h2</artifactId> <version>1.4.200</version> </dependency> </dependencies> </project> 

Step 2: Create Hibernate Configuration File

Create a file named hibernate.cfg.xml in the src/main/resources directory.

<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <property name="hibernate.dialect">org.hibernate.dialect.H2Dialect</property> <property name="hibernate.connection.driver_class">org.h2.Driver</property> <property name="hibernate.connection.url">jdbc:h2:mem:testdb</property> <property name="hibernate.connection.username">sa</property> <property name="hibernate.connection.password"></property> <property name="hibernate.hbm2ddl.auto">update</property> <property name="hibernate.show_sql">true</property> <property name="hibernate.format_sql">true</property> </session-factory> </hibernate-configuration> 

Step 3: Create an Entity Class with @CreationTimestamp and @UpdateTimestamp

Create a package named com.example.entity and a class named Message.

package com.example.entity; import jakarta.persistence.*; import org.hibernate.annotations.CreationTimestamp; import org.hibernate.annotations.UpdateTimestamp; import java.time.LocalDateTime; @Entity public class Message { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; private String text; @CreationTimestamp @Column(updatable = false) private LocalDateTime createdAt; @UpdateTimestamp private LocalDateTime updatedAt; public Message() {} public Message(String text) { this.text = text; } public Long getId() { return id; } public void setId(Long id) { this.id = id; } public String getText() { return text; } public void setText(String text) { this.text = text; } public LocalDateTime getCreatedAt() { return createdAt; } public LocalDateTime getUpdatedAt() { return updatedAt; } @Override public String toString() { return "Message{id=" + id + ", text='" + text + '\'' + ", createdAt=" + createdAt + ", updatedAt=" + updatedAt + '}'; } } 

Explanation of @CreationTimestamp and @UpdateTimestamp annotations

• @CreationTimestamp: This annotation marks a field to be automatically populated with the current timestamp when the entity is first persisted (saved) to the database. The @Column(updatable = false) annotation ensures that this value is not updated once it is set.

• @UpdateTimestamp: This annotation marks a field to be automatically populated with the current timestamp whenever the entity is updated.

Step 4: Create Hibernate Utility Class

Create a package named com.example.util and a class named HibernateUtil.

package com.example.util; import org.hibernate.SessionFactory; import org.hibernate.boot.registry.StandardServiceRegistryBuilder; import org.hibernate.cfg.Configuration; import org.hibernate.service.ServiceRegistry; public class HibernateUtil { private static SessionFactory sessionFactory; static { try { Configuration configuration = new Configuration().configure(); ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder() .applySettings(configuration.getProperties()).build(); sessionFactory = configuration.buildSessionFactory(serviceRegistry); } catch (Throwable ex) { throw new ExceptionInInitializerError(ex); } } public static SessionFactory getSessionFactory() { return sessionFactory; } } 

Step 5: Create Main Class

Create a package named com.example and a class named Main.

package com.example; import com.example.entity.Message; import com.example.util.HibernateUtil; import org.hibernate.Session; import org.hibernate.Transaction; public class Main { public static void main(String[] args) { // Save a new message Session session = HibernateUtil.getSessionFactory().openSession(); Transaction transaction = session.beginTransaction(); Message message = new Message("Hello, Timestamps!"); session.save(message); transaction.commit(); session.close(); // Retrieve the message session = HibernateUtil.getSessionFactory().openSession(); Message retrievedMessage = session.get(Message.class, message.getId()); System.out.println("Retrieved Message: " + retrievedMessage); // Update the message transaction = session.beginTransaction(); retrievedMessage.setText("Hello, Updated Timestamps!"); session.update(retrievedMessage); transaction.commit(); // Retrieve the updated message Message updatedMessage = session.get(Message.class, retrievedMessage.getId()); System.out.println("Updated Message: " + updatedMessage); session.close(); // Close the SessionFactory HibernateUtil.getSessionFactory().close(); } } 

Step 6: Run the Application

1. Run the Main class.
2. The output in the console should be:

Hibernate: create table Message (id bigint generated by default as identity, createdAt timestamp, text varchar(255), updatedAt timestamp, primary key (id)) Hibernate: insert into Message (createdAt, text, updatedAt) values (?, ?, ?) Hibernate: select message0_.id as id1_0_0_, message0_.createdAt as createdA2_0_0_, message0_.text as text3_0_0_, message0_.updatedAt as updatedA4_0_0_ from Message message0_ where message0_.id=? Retrieved Message: Message{id=1, text='Hello, Timestamps!', createdAt=2024-05-15T10:20:30, updatedAt=2024-05-15T10:20:30} Hibernate: update Message set text=?, updatedAt=? where id=? Hibernate: select message0_.id as id1_0_0_, message0_.createdAt as createdA2_0_0_, message0_.text as text3_0_0_, message0_.updatedAt as updatedA4_0_0_ from Message message0_ where message0_.id=? Updated Message: Message{id=1, text='Hello, Updated Timestamps!', createdAt=2024-05-15T10:20:30, updatedAt=2024-05-15T10:25:30} 

Conclusion

You have successfully created an example using Hibernate with @CreationTimestamp and @UpdateTimestamp annotations. This tutorial covered setting up a Maven project, configuring Hibernate, creating an entity class with timestamp fields, and performing basic CRUD operations to observe the automatic population of the timestamp fields.