Retrieve objects from database

There are many ways to retrieve values from a table. Below example is one of doing it. Note that since the table has already been generated and has some values in it, we set the value of "hbm2ddl.auto" to update.

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

    <session-factory>

        <!-- Database connection settings -->
        <property name="connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
        <property name="connection.url">jdbc:oracle:thin:@localhost:1521:xe</property>
        <property name="connection.username">hr</property>
        <property name="connection.password">hr</property>

        <!-- JDBC connection pool (use the built-in) -->
        <property name="connection.pool_size">1</property>

        <!-- SQL dialect -->
        <property name="dialect">org.hibernate.dialect.OracleDialect</property>

        <!-- Disable the second-level cache  -->
        <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>

        <!-- Echo all executed SQL to stdout -->
        <property name="show_sql">true</property>

        <!-- Drop and re-create the database schema on startup -->
        <property name="hbm2ddl.auto">update</property>

        <!-- Names the annotated entity class -->
        <mapping class="com.ram.dao.UserDetails"/>

    </session-factory>

</hibernate-configuration>

package com.ram.dao;

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;
 }
}

package com.ram.hibernate;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

import com.ram.dao.UserDetails;

public class RetrieveObjectsExample {
 public static void main(String[] args) {
  UserDetails userDetails = new UserDetails();
  
  SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
  Session session = sessionFactory.openSession();
  session.beginTransaction();
  
  //session.get() will retrieve the value from the data base 
  userDetails = (UserDetails)session.get(UserDetails.class, 1);
  System.out.println("UserName of Id 1 is "+userDetails.getUserName());
  session.close();
 }
}

Execute RetrieveObjectsExample.java and it will retrieve the user name for the Id 1.