hibernate
Persist object with Hibernate
This is an example of how to persist an object with Hibernate. To persist an object with Hibernate we have set the example below:
- In
PersistOjectWithHibernate
we use the Hibernate API to make the interface with the database. - We create a new
Configuration
, that allows the application to specify properties and mapping documents to be used when creating aSessionFactory
. Usually an application will create a singleConfiguration
, build a single instance ofSessionFactory
and then instantiate Sessions in threads servicing client requests. - Using
configure()
API method we use the mappings and properties specified in an application resource namedhibernate.cfg.xml
. Then, withbuildSessionFactory()
we instantiate a newSessionFactory
, using the properties and mappings in this configuration. TheSessionFactory
will be immutable, so changes made to the Configuration after building theSessionFactory
will not affect it. - Use the
getCurrentSession()
API method to obtain the current session. - Use the
beginTransaction()
API method to begin a unit of work and return the associated Transaction object. If a new underlying transaction is required, begin the transaction. Otherwise continue the new work in the context of the existing underlying transaction. - Create a new object, here a new
Employee
object and usesave(Object object)
API method of Session to persist the given transient instance to the database. - Use
getTransaction()
API method ofSession
andcommit()
API method of Transaction to commit the Transaction.
In the code snippets that follow, you can see the PersistOjectWithHibernate
Class that applies all above steps. You can also take a look at the hibernate.cfg.xml
file, that holds all configuration for Hibernate, such as JDBC connection settings, and employee.hbm.xml
file that holds the mapping configuration between the Employee
object and the Employee
table.
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 | package com.javacodegeeks.snippets.enterprise; import java.util.Date; import org.hibernate.HibernateException; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.cfg.Configuration; public class PersistOjectWithHibernate { private static SessionFactory sessionFactory; public static void main(String[] args) { sessionFactory = new Configuration().configure().buildSessionFactory(); Session session = sessionFactory.getCurrentSession(); Employee employee = new Employee(); employee.setName( "Jack" ); employee.setSurname( "Thomson" ); employee.setTitle( "QA Engineer" ); employee.setCreated( new Date()); try { session.beginTransaction(); session.save(employee); session.getTransaction().commit(); } catch (HibernateException e) { e.printStackTrace(); session.getTransaction().rollback(); } } } |
hibernate.cfg.xml
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 | <? xml version = '1.0' encoding = 'utf-8' ?> <! DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" < hibernate-configuration > < session-factory > <!-- JDBC connection settings --> < property name = "connection.driver_class" >com.mysql.jdbc.Driver</ property > < property name = "connection.url" >jdbc:mysql://localhost/companydb</ property > < property name = "connection.username" >jcg</ property > < property name = "connection.password" >jcg</ property > <!-- JDBC connection pool, use Hibernate internal connection pool --> < property name = "connection.pool_size" >5</ property > <!-- Defines the SQL dialect used in Hiberante's application --> < property name = "dialect" >org.hibernate.dialect.MySQLDialect</ property > <!-- Enable Hibernate's automatic session context management --> < property name = "current_session_context_class" >thread</ property > <!-- Disable the second-level cache --> < property name = "cache.provider_class" >org.hibernate.cache.NoCacheProvider</ property > <!-- Display and format all executed SQL to stdout --> < property name = "show_sql" >true</ property > < property name = "format_sql" >true</ property > <!-- Drop and re-create the database schema on startup --> < property name = "hbm2ddl.auto" >update</ property > <!-- Mapping to hibernate mapping files --> < mapping resource = "Employee.hbm.xml" /> </ session-factory > </ hibernate-configuration > |
Employee.hbm.xml
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 | <? xml version = "1.0" ?> <! DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" < hibernate-mapping > < class name = "com.javacodegeeks.snippets.enterprise.Employee" table = "employee" > < id name = "id" column = "id" > < generator class = "native" /> </ id > < property name = "name" not-null = "true" length = "50" /> < property name = "surname" not-null = "true" length = "50" /> < property name = "title" length = "50" /> < property name = "created" type = "timestamp" /> </ class > </ hibernate-mapping > |
1 2 3 4 5 6 7 8 | CREATE TABLE `companydb`.`employee` ( `id` INTEGER UNSIGNED NOT NULL AUTO_INCREMENT, ` name ` VARCHAR (45) NOT NULL , `surname` VARCHAR (45) NOT NULL , `title` VARCHAR (45) NOT NULL , `created` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP , PRIMARY KEY (`id`) ); |
Output:
Hibernate:
insert
into
employee
(name, surname, title, created)
values
(?, ?, ?, ?)
This was an example of how to persist an object with Hibernate.