Java Spring Hibernate Example Mysql
Hibernate Example with MySQL Database
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 athttps://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 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
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> Note that we are using mysql-connector-java driver dependency to connect the Java Hibernate application to the MySQL database:
<!-- 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 the 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 an 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.
Let's create aStudent entity class undernet.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 theStudent 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
TheHibernateUtil 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 separateStudentDao 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
Conclusion
In this article, we have created a step-by-step hibernate application to demonstrate the use of Java-based configuration without usinghibernate.cfg.xml to connectMySQL database.
References
- Hibernate ORM 5.4.0.Final User Guide
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Source: https://www.javaguides.net/2021/08/hibernate-example-with-mysql-database.html
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