Simple Hibernate Table Creation from Scratch

Step1: Create a Bean for which Table should be created in Database
Step2: Create a Class which uses the bean.

Step 1

package com.mugil.dto;

import javax.persistence.Entity;
import javax.persistence.Id;

@Entity 
public class UserDetails {
	@Id	
	private int userId;
	private String userName;
	
	public int getUserId() {
		return userId;
	}
	
	public void setUserId(int userId) {
		this.userId = userId;
	}
	
	public String getUserName() {
		return userName;
	}
	
	public void setUserName(String userName) {
		this.userName = userName;
	}
}

Step 2

package com.mugil.access;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;

import com.mugil.dto.UserDetails;

public class CreateUser {
	private static ServiceRegistry serviceRegistry;
	private static SessionFactory sessionFactory;
	
	public static void main(String[] args) {
		UserDetails objUserDetail =  new UserDetails();
		objUserDetail.setUserId(101);
		objUserDetail.setUserName("Mugil");
		
		SessionFactory sessionFact = createSessionFactory();
		Session session = sessionFact.openSession();
		session.beginTransaction();
		session.save(objUserDetail);
		session.getTransaction().commit();	
	}
	
	
	public static SessionFactory createSessionFactory() {
	    Configuration configuration = new Configuration();
	    configuration.configure();
	    serviceRegistry = new StandardServiceRegistryBuilder().applySettings(
	            configuration.getProperties()).build();
	    sessionFactory = configuration.buildSessionFactory(serviceRegistry);
	    return sessionFactory;
	}
}

In Some cases the hibernate.cfg.xml might become unrecognized.In such case the code should be changed to force the config to be picked from the file location.

public static SessionFactory createSessionFactory() 
{
  Configuration configuration = new Configuration().configure();	  
  configuration.configure("hibernate.cfg.xml");	  
  configuration.addAnnotatedClass(com.mugil.tutor.UserDetails.class);
	  
  serviceRegistry = new   StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build();
  sessionFactory = configuration.buildSessionFactory(serviceRegistry);
  return sessionFactory;
}

Hibernate uses SessionFactory pattern internally as below

SessionFactory sessionFact = createSessionFactory();
Session session = sessionFact.openSession();
session.beginTransaction();
session.save(objUserDetail);
session.getTransaction().commit();	

1.Create Object for SessionFactory
2.Open Session to begin Transaction
3.Begin Transaction using beginTransaction() Method
4.Save the Object by Passing Object of the bean
5.Complete the Transaction using commit

Annotations
@Entity – Means entity as a whole>table would be created by the Name of the Entity
@Id – Tells the Primary Key

Having a Different table name from Class Name
Annotations

@Entity(name="User_Details")
public class Users 
{
 .
 .
}

Table with User_Details would be created instead of Users

Having a Different Column name from Object Name
Annotations

@Entity(name="User_Details")
public class Users 
{
 @Id
 @Column(name="USER_ID")
 private String UserId;
 .
 .
}

Columns with User_Id would be created instead of UserId

Appending String to Getters

public void setName(String name) 
{
  Name = name + " Append Test ";
}

Appending String to Getters

@Entity
@Table (name="User_Details")
public class Users 
{

}

The Entity Name Still remains the same but the table Name is different.

@Basic Annotation – Tells Hibernate to persist which it does by default

public class Users 
{
 @Basic
 private String UserName;
 . 
 .
}

@Basic has 2 Parameters – Fetch, optional. The only time you use @Basic is while applying the above options.

@Transient Annotation – Tells Hibernate to not store data in database

public class Users 
{
 @Transient
 private String UserName;
 . 
 .
}

@Temporal Annotation – Tells Hibernate to specify Date or Time

public class Users 
{
 @Temporal (TemporalType.Date)
 private String joinedDate;
 . 
 .
}

Without @Temporal the joinedDate is store along with TimeStamp in DB. Now using TemporalType(which is ENUM) you can select the type of data which can be stored in Database.

@Lob – Tells Hibernate to specify Date or Time

public class Users 
{
 @Lob
 private String Address;
 . 
 .
}

Tells the database field should be created as CLOB instead of VARCHAR(255).