Session

 Before writing the business component,we need to understand a hibernate 'session'.A hibernate session is an instance of org.hibernate.SessionopenSession() of SessionFactory. Every database operation begins and ends with a Session. For example,we can beginTransaction(),save(),update() or delete() an object with the help of a Session. and is obtained by calling

Our business component will use the Session to perform its business operations.

package com.sycorax.hibernate.client;

import org.hibernate.Session;

import com.sycorax.hibernate.User;

/**  

* UserManager  *

@author sycorax

 */

public class UserManager {

private Session session = null;

public UserManager(Session session) {

if(session == null)

throw new RuntimeException("Invalid session object. Cannot instantiate the UserManager");

this.session = session;

}

public void saveUser(User user) {

session.save(user);

}

public void updateUser(User user) {

session.update(user);

}

public void deleteUser(User user) {

session.delete(user);

}

}

Let us write a test client that utilizes the different methods of the UserManager we have just introduced. We will obtain the SessionFactory and open a session and then call different methods of the UserManager to see if they work or not.

package com.sycorax.hibernate.client;
import org.hibernate.*;
import org.hibernate.cfg.Configuration;
import com.sycorax.hibernate.*;

public class TestClient {
/*    * This method builds a default user to check if the Hiernate configuration is working or not    */
public User buildUser() {
User user = new User();
user.setFirstName("Gc");
user.setLastName("Das");
user.setAge(25);
user.setEmail("info@sycorax.co.in");
return user;
}
/*    * This method gets the default SessionFactory configured in hibernate.cfg.xml and opens a session    */
public Session openSession()
{  
SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
Session session =sessionFactory.openSession();
return session;
}

public User testSaveUser(UserManager manager)  {
User user = buildUser();
manager.saveUser(user);
System.out.println("User saved with ID = " user.getUserId());
return user;
}

public void testUpdateUser(UserManager manager,User user)  { user.setFirstName("Andrew");
manager.updateUser(user);
System.out.println("User updated with ID = " user.getUserId());
}

public void testDeleteUser(UserManager manager,User user)  { manager.deleteUser(user);
System.out.println("User deleted with ID = " user.getUserId());
}
public static void main(String[] args)  {
TestClient client = new TestClient();
Session session = client.openSession();
UserManager manager = new UserManager(session);

User user = client.testSaveUser(manager);

client.testUpdateUser(manager,user);

client.testDeleteUser(manager,user);
session.flush();
}
}

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