In this tutorial, we will learn how to create Hibernate application and connect Hibernate application to the MySQL database. We use Maven as a dependency management tool.
Learn and master Hibernate framework at https://www.javaguides.net/p/hibernate-tutorial.html
Let's use Java-based configuration and JPA annotations for mapping in this tutorial.
For XML-based configuration, check out ✅ Hibernate 5 XML Configuration Example.
Technologies and tools used
- Hibernate 5.3.7.Final
- IDE - Eclipse Noen
- Maven 3.5.3
- JavaSE 1.8
- MySQL - 8.0.13
Let's start developing step by step Hibernate application using Maven as a project management and build tool.
Development Steps
- Create a Simple Maven Project
- Project Directory Structure
- Add jar Dependencies to pom.xml
- Creating the JPA Entity Class(Persistent class)
- Create a Hibernate configuration file - Java Configuration
- Create StudentDao Class
- Create the Main class and Run an Application
1. Create a Simple Maven Project
Use the How to Create a Simple Maven Project in Eclipse article to create a simple Maven project in Eclipse IDE.
2. Project Directory Structure
The project directory structure for your reference -
3. Add jar Dependencies to pom.xml
Open the pom.xml file in your Hibernate project and add the below code to it:
<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>
<parent>
<groupId>net.javaguides.hibernate</groupId>
<artifactId>hibernate-tutorial</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<artifactId>hibernate-java-config-example</artifactId>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.13</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-core -->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>5.3.7.Final</version>
</dependency>
</dependencies>
<build>
<sourceDirectory>src/main/java</sourceDirectory>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.5.1</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
</build>
</project><!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java --> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>8.0.13</version> </dependency>
We are using Hibernate core dependency:
<!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-core --> <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-core</artifactId> <version>5.3.7.Final</version> </dependency>
We are using the maven-compiler-plugin to compile Java Hibernate application with JRE 1.8 version:
<plugin> <artifactId>maven-compiler-plugin</artifactId> <version>3.5.1</version> <configuration> <source>1.8</source> <target>1.8</target> </configuration> </plugin>
4. Creating the JPA Entity Class(Persistent class)
Let's create a Student persistent class that is mapped to a student database table:
A simple Persistent class should follow some rules:
- A no-arg constructor: It is recommended that you have a default constructor at least package visibility so that hibernate can create the instance of the Persistent class by the newInstance() method.
- Provide an identifier property: It is better to assign an attribute as id. This attribute behaves as a primary key in a database.
- Declare getter and setter methods: The Hibernate recognizes the method by getter and setter method names by default.
- Prefer non-final class: Hibernate uses the concept of proxies, which depends on the persistent class. The application programmer will not be able to use proxies for lazy association fetching.
Create a Student entity class under net.javaguides.hibernate.entity package as follows.
package net.javaguides.hibernate.entity;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity
@Table(name = "student")
public class Student {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id")
private int id;
@Column(name = "first_name")
private String firstName;
@Column(name = "last_name")
private String lastName;
@Column(name = "email")
private String email;
public Student() {
}
public Student(String firstName, String lastName, String email) {
this.firstName = firstName;
this.lastName = lastName;
this.email = email;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
@Override
public String toString() {
return "Student [id=" + id + ", firstName=" + firstName + ", lastName=" + lastName + ", email=" + email + "]";
}
}JPA annotations are used in mapping java objects to the database tables, columns, etc.
JPA annotations that we are using in the Student entity:
@Entity - This annotation specifies that the class is an entity.
@Table - This annotation specifies the table in the database with which this entity is mapped.
@Column - The @Column annotation is used to specify the mapping between a basic entity attribute and the database table column.
@Id - This annotation specifies the primary key of the entity
@GeneratedValue - This annotation specifies the generation strategies for the values of primary keys.
5. Create a Hibernate configuration file - Java Configuration
The HibernateUtil Java configuration file contains information about the database and mapping file.
Let's create a HibernateUtil file and write the following code in it.
package net.javaguides.hibernate.util;
import java.util.Properties;
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.cfg.Environment;
import org.hibernate.service.ServiceRegistry;
import net.javaguides.hibernate.entity.Student;
public class HibernateUtil {
private static SessionFactory sessionFactory;
public static SessionFactory getSessionFactory() {
if (sessionFactory == null) {
try {
Configuration configuration = new Configuration();
// Hibernate settings equivalent to hibernate.cfg.xml's properties
Properties settings = new Properties();
settings.put(Environment.DRIVER, "com.mysql.cj.jdbc.Driver");
settings.put(Environment.URL, "jdbc:mysql://localhost:3306/hibernate_db?useSSL=false");
settings.put(Environment.USER, "root");
settings.put(Environment.PASS, "root");
settings.put(Environment.DIALECT, "org.hibernate.dialect.MySQL5Dialect");
settings.put(Environment.SHOW_SQL, "true");
settings.put(Environment.CURRENT_SESSION_CONTEXT_CLASS, "thread");
settings.put(Environment.HBM2DDL_AUTO, "create-drop");
configuration.setProperties(settings);
configuration.addAnnotatedClass(Student.class);
ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()
.applySettings(configuration.getProperties()).build();
sessionFactory = configuration.buildSessionFactory(serviceRegistry);
} catch (Exception e) {
e.printStackTrace();
}
}
return sessionFactory;
}
}6. Create StudentDao Class
Let's create a separate StudentDao class to separate out hibernate and database-related stuff.
package net.javaguides.hibernate.dao;
import java.util.List;
import org.hibernate.Session;
import org.hibernate.Transaction;
import net.javaguides.hibernate.entity.Student;
import net.javaguides.hibernate.util.HibernateUtil;
public class StudentDao {
public void saveStudent(Student student) {
Transaction transaction = null;
try (Session session = HibernateUtil.getSessionFactory().openSession()) {
// start a transaction
transaction = session.beginTransaction();
// save the student object
session.save(student);
// commit transaction
transaction.commit();
} catch (Exception e) {
if (transaction != null) {
transaction.rollback();
}
e.printStackTrace();
}
}
public List < Student > getStudents() {
try (Session session = HibernateUtil.getSessionFactory().openSession()) {
return session.createQuery("from Student", Student.class).list();
}
}
}7. Create the main App class and Run an Application
Let's test Hibernate application to connect MySQL database.
package net.javaguides.hibernate;
import java.util.List;
import net.javaguides.hibernate.dao.StudentDao;
import net.javaguides.hibernate.entity.Student;
public class App {
public static void main(String[] args) {
StudentDao studentDao = new StudentDao();
Student student = new Student("Ramesh", "Fadatare", "rameshfadatare@javaguides.com");
studentDao.saveStudent(student);
List < Student > students = studentDao.getStudents();
students.forEach(s - > System.out.println(s.getFirstName()));
}
}Output
GitHub Repository
The complete source code of this article is available on my GitHub Repository - https://github.com/RameshMF/Hibernate-ORM-Tutorials
Conclusion
In this article, we have created a step-by-step hibernate application to demonstrate the use of Java-based configuration without using hibernate.cfg.xml to connect MySQL database.
You can learn more about Hibernate ORM Framework at Hibernate Tutorial
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