Java Object persist by Hibernate 4.x and Postgres 9

What is Hibernate ?

Hibernate is an Object Relational Mapping(ORM)  .  Hibernate is an open source  tool which comes under GNU Lesser General Public License (LGPL) .  Hibernate allow a plain java object mapping to relational database .
Hibernate  persistent framework created by Gavin King in 2001.

How to persist an plain java object(POJO) to relational database .

Step 1 . Create Hibernate.cfg.xml configuration file .
Step 2 . Create Persistent java class .
Step 3 . Create  Main class to create session  and create java object . and persist class .




Hibernate.cfg.xml  : contain various configuration property like database driver name ,database url
                                 user name and password and all mapping class .

<?xml version = "1.0" encoding = "utf-8"?>

<!DOCTYPE hibernate-configuration SYSTEM

"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

<session-factory>

<property name="hibernate.show_sql">true</property>

<property name="hbm2ddl.auto">update</property>
<property name="hibernate.dialect">org.hibernate.dialect.ProgressDialect</property>
<property name="hibernate.connection.driver_class">org.postgresql.Driver</property>
<!-- Assume hibernate is the database name -->

 <property name="hibernate.connection.url">jdbc:postgresql://localhost/hibernate</property>

 <property name="hibernate.connection.username">postgres</property>

<property name="hibernate.connection.password">postgres</property>

<mapping class="Employee" />

</session-factory>

</hibernate-configuration>


 

Step 2 Create persistent java Class :

to Create java persistent class just create simple plain java class  and decorated minimum two annotation

@Entity   for mark java class  hibernate entity and @Id     to mark field for primary key .        

 

import javax.persistence.Entity;

import javax.persistence.Id;

 

@Entity

public class Employee {

@Id

private int empId;

private String emapName;

private String companyName;

 

public int getEmpId() {

return empId;

 

}

public void setEmpId(int empId) {

this.empId = empId;

 

}

public String getEmapName() {

return emapName;

 

}

public void setEmapName(String emapName) {

this.emapName = emapName;

 

}

public String getCompanyName() {

return companyName;

 

}

public void setCompanyName(String companyName) {

this.companyName = companyName;

 

}

 

Step  Create a main class to persist class : To persistent a java object with hibernate we have require Configuration object  , SessionFactory object and session object .

 

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.hibernate.Transaction;

import org.hibernate.cfg.Configuration;

import org.hibernate.service.ServiceRegistry;

import org.hibernate.service.ServiceRegistryBuilder;

 

public class HibernateTest {

 

public static void main(String[] args) {

 

Configuration configuration = new Configuration(); //  

configuration.configure("hibernate.cfg.xml");

ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties())

 buildServiceRegistry();

SessionFactory sessionFactory = configuration.buildSessionFactory(serviceRegistry);

 

Session session = sessionFactory.openSession();

Transaction transaction = session.beginTransaction();

 

Employee employee = new Employee();

employee.setEmpId(1);

employee.setCompanyName("Johny kumar");

employee.setCompanyName("Google.com");

 

Employee employee2 = new Employee();

employee2.setEmpId(2);

employee2.setCompanyName("Ambrish");

employee2.setCompanyName("Amazon");

 session.persist(employee);

session.persist(employee2);

 

transaction.commit();

session.flush();

 

session.close();

System.out.println("Saved.............");

}

}

In Database table

 

 

 

 

 

 

 

 

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