assigned generator in hibernate example

Tools and Technologies we are using here:

JDK 7
Hibernate 4.3.7
MySql 5.1.10
Eclipse Juno 4.2
Maven 3.2

Overview of the Project Structure:

Main Objects of this project are:

pom.xml
hibernate.cfg.xml
Generator.hbm.xml
database

Step 1. Create a maven project and add the below given dependencies for hibernate and mysql, inside your pom.xml file.

<dependencies>
  <!-- Hibernate Dependency -->
  <dependency>
   <groupId>org.hibernate</groupId>
   <artifactId>hibernate-core</artifactId>
   <version>4.3.7.Final</version>
  </dependency>
  
  <!-- MySql Connector dependency -->
  <dependency>
   <groupId>mysql</groupId>
   <artifactId>mysql-connector-java</artifactId>
   <version>5.1.10</version>
  </dependency>

 </dependencies>

Step 2. Create a hibernate.cfg.xml file:
Create hibernate.cfg.xml file inside src/main/resources folder.

hibernate.cfg.xml

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
  
<hibernate-configuration>
    <session-factory>
        <!-- Database connection settings -->
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://localhost:3306/hibernate_tutorial</property>
        <property name="connection.username">root</property>
        <property name="connection.password">root</property>
         
        <!-- SQL dialect -->
        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
 
        <!-- Echo all executed SQL to stdout -->
        <property name="show_sql">true</property>
     <property name="hbm2ddl.auto">update</property>
        <mapping resource="Generator.hbm.xml"/>
          
    </session-factory>
</hibernate-configuration>

Step 3. Create Generator.hbm.xml mapping file inside src/main/resources folder. See the child element of id is generator element and we are using here assigned as the value of generator.

Generator.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- Generated 29 Oct, 2014 8:47:37 PM by Hibernate Tools 3.4.0.CR1 -->
<hibernate-mapping>
    <class name="com.hibernate.generator.pojo.Generator" table="generator">
        <id name="generatorId" type="java.lang.Integer" column="generator_id" >
            <generator class="assigned"></generator>
  </id>
        <property name="generatorName" column="generator_name">
            <type name="org.hibernate.type.EnumType">
           <param name="enumClass">com.hibernate.generator.util.GeneratorType</param>
           <param name="type">12</param>
        </type>
        </property>
        <property name="description" column="description"/>
    </class>
</hibernate-mapping>

Step 4. Create HibernateUtility.java class to return SessionFactory in hibernate 4.3.7

HibernateUtility.java

package com.hibernate.generator.util;

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

public class HibernateUtility {
 private static final SessionFactory sessionFactory = buildSessionFactory();

 private static SessionFactory buildSessionFactory() {
  Configuration configuration = new Configuration();
  configuration.configure();

  ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()
    .applySettings(configuration.getProperties()).build();
  SessionFactory sessionFactory = configuration
    .buildSessionFactory(serviceRegistry);

  return sessionFactory;
 }

 public static SessionFactory getSessionFactory() {
  return sessionFactory;
 }
}

Step 5. Create GeneratorType Enum, GeneratorType is a data type for our generator_name column. This is just a data type we are using here instead of varchar, in our generator table we are using enum, so we have created an Enum type to mapped the generator_name property.

GeneratorType

package com.hibernate.generator.util;

public enum GeneratorType {
IDENTITY, INCREMENT, HILO, ASSIGNED, NATIVE, UUID, GUID, SELECT
}

Step 6. Create Generator.java pojo class, It has all the properties defined inside the Generator.hbm.xml file.

Generator

package com.hibernate.generator.pojo;

import com.hibernate.generator.util.GeneratorType;

public class Generator {

 private int generatorId;
 private GeneratorType generatorName;
 private String description;

 public int getGeneratorId() {
  return generatorId;
 }

 public void setGeneratorId(int generatorId) {
  this.generatorId = generatorId;
 }

 public GeneratorType getGeneratorName() {
  return generatorName;
 }

 public void setGeneratorName(GeneratorType generatorName) {
  this.generatorName = generatorName;
 }

 public String getDescription() {
  return description;
 }

 public void setDescription(String description) {
  this.description = description;
 }

 @Override
 public String toString() {
  return "Generator [generatorId=" + generatorId + ", generatorName="
    + generatorName + ", description=" + description + "]";
 }

}

Step 7. Create GeneratorDAO.java class and provide the implementation of CRUD method.

GeneratorDAO

package com.hibernate.generator.dao;

import org.hibernate.Session;
import org.hibernate.SessionFactory;

import com.hibernate.generator.pojo.Generator;
import com.hibernate.generator.util.HibernateUtility;

public class GeneratorDAO {
 private static SessionFactory sessionFactory;
 static {
  sessionFactory = HibernateUtility.getSessionFactory();
 }

 public static Generator findById(long id) {
  Session session = sessionFactory.openSession();
  Generator generator = (Generator) session.load(Generator.class, id);

  return generator;
 }

 public static Generator save(Generator generator) {
  Session session = sessionFactory.openSession();

  session.beginTransaction();

  session.save(generator);

  session.getTransaction().commit();

  return generator;
 }

 public static Generator update(Generator generator) {
  Session session = sessionFactory.openSession();

  session.beginTransaction();

  session.merge(generator);

  session.getTransaction().commit();

  return generator;

 }

 public static void delete(Generator generator) {
  Session session = sessionFactory.openSession();

  session.beginTransaction();

  session.delete(generator);

  session.getTransaction().commit();

 }
}

Step 8. Create GeneratorService.java class to call the methods of GeneratorDAO class

GeneratorService

package com.hibernate.generator.service;

import com.hibernate.generator.dao.GeneratorDAO;
import com.hibernate.generator.pojo.Generator;
import com.hibernate.generator.util.GeneratorType;

public class GeneratorService {
 public static void main(String[] args) {
  Generator generator = new Generator();
  generator.setDescription("assigned generator class used");
  // here we have assigned the primary key value
  generator.setGeneratorId(999);
  generator.setGeneratorName(GeneratorType.ASSIGNED);
  System.out.println(GeneratorDAO.save(generator));
 }
}

Run the GeneratorService, It will create a new record inside the generator table of hibernate_tutorial database. Here we have assigned the primary key value as 999.

OUT PUT:
Hibernate: insert into generator (generator_name, description, generator_id) values (?, ?, ?)
Generator [generatorId=999, generatorName=ASSIGNED, description=assigned generator class used]

assigned generator in hibernate example

Tools and Technologies we are using here:

Download the complete example from here Source Code

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