Hibernate - DAO

We will now update our UserDAO to use Hibernate.

Your UserDAO.java will now look like this:

 package org.confucius;  
   
 import org.hibernate.Session;  
 import org.hibernate.Transaction;  
   
 public class UserDAO {  
      public static void persist (User user) throws Exception{  
     Session session = HibernateUtil.getSessionFactory().openSession();  
     Transaction tx = session.beginTransaction();  
   
     try {  
       session.persist(user);  
       tx.commit();  
     }  
     catch (Exception e){  
          tx.rollback();  
          throw e;  
     }  
       
     session.close();  
      }  
 }  

We start by getting a new session from the Hibernate SessionFactory.
We start a new transaction, persist the user, then commit (or rollback) the transaction.

Strictly speaking, we did not have to do this in a transaction. Because there is only one database interaction. However, it is highly recommended in Hibernate to do all database interactions inside a transaction. It keeps the internal state of the Hibernate session clean.

Finally, update the TestPersistence.java to use the new DAO, like this:

 package org.confucius;  
   
   
 public class TestPersistence {  
   
      public static void main(String[] args) {  
           User joe = new User();  
           joe.setFirstName("Joe");  
           joe.setLastName("Trumpet");  
             
           try {  
                UserDAO.persist(joe);  
           } catch (Exception e) {  
                e.printStackTrace();  
           }  
      }  
 }     

R-click on TestPersistence.java in Eclipse Navigator view. Select Run As-->Java Application.

Now if you go to your MySQL Command Line Client, you will see a new table 'user' containing 'Joe Trumpet', like this:

 mysql> select * from user;  
 +----+-----------+----------+  
 | id | firstName | lastName |  
 +----+-----------+----------+  
 | 1 | Joe    | Trumpet |  
 +----+-----------+----------+  
 1 row in set (0.00 sec)