Dirty Checking In Hibernate
In this section we will read about the dirty checking in hibernate.
Dirty Checking is the feature of hibernate that helps in to automatically detect the modification of object in a transaction and update, if modified, the database. Inspection is a strategy that the hibernate uses for dirty checking. In an inspection strategy, a snapshot of the object at the time which it is loaded from the database is stored into the memory. In case of the session is flushed out, the stored object and the current state of object is compared by the Hibernate and if there is difference found in objects then it marks that object to dirty. A persistent state of object in hibernate specifies its bound for a particular hibernate Session and this object is in under surveillance of Hibernate. If any changes to the objects is found hibernate executes the SQL update statement.
Example
Here I am giving a simple example which will demonstrate you about the dirty checking in hibernate. In this example you will see how the hibernate executes the update statement SQL. Here we will create a simple application into which we will show you how a update statement is called by the hibernate and the field in the database is updated. Here I have created a package in Java net.roseindia then I have created a JavaBean into which I have defined some properties like id and name and their setter getter method. Then I have created a class named PersonDetail.java into which I have generate a condition for generating the dirty checking. Before, creating the Java project we need to create a table named with person1 (Id, Name) and then inserted some dummy records into the table.
Create Table named person1
CREATE TABLE `person1` ( `Id` int(10) NOT NULL, `Name` varchar(15) default NULL, PRIMARY KEY (`Id`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1
Insert some record into the table
insert into person1(Id, Name) values(1, 'Deepak')
Then the table will contain the value as below :
Now, Create the Java Application
Directory Structure
Person.java
package net.roseindia;
public class Person
{
int id;
String name;
public Person()
{
}
public Person(int id, String name) {
super();
this.id = id;
this.name = name;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
PersonDetail.java
package net.roseindia;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
public class PersonDetail
{
private static SessionFactory sessionFactory;
private static ServiceRegistry serviceRegistry;
public static void main(String[] args)
{
Session session = null;
try
{
try
{
Configuration cfg = new Configuration().addResource(
"person.hbm.xml").configure();
serviceRegistry = new ServiceRegistryBuilder().applySettings(
cfg.getProperties()).buildServiceRegistry();
sessionFactory = cfg.buildSessionFactory(serviceRegistry);
}
catch (Throwable ex)
{
System.err.println("Failed to create sessionFactory object."+ ex);
throw new ExceptionInInitializerError(ex);
}
session = sessionFactory.openSession();
Transaction tx = session.beginTransaction();
//loading a person object of id = 1
Person person = (Person)session.get(Person.class, new Integer(1));
//print the person name
System.out.println("person.getName()=======>"+person.getName());
//modify the person name
person.setName("Roseindia");
tx.commit();
session.flush();
System.out.println("Done");
} catch (Exception e) {
System.out.println(e.getMessage());
} finally {
session.close();
}
}
}
Person.hbm.xml
<?xml version='1.0'?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <hibernate-mapping package="net.roseindia"> <class name="Person" table="person1"> <id name="id" type="int" column="Id" > <generator class="assigned"/> </id> <property name="name"> <column name="Name" /> </property> </class> </hibernate-mapping>
hibernate.cfg.xml
<?xml version='1.0' encoding='utf-8'?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD//EN" "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/record </property> <property name="hibernate.connection.username">root</property> <property name="hibernate.connection.password">root</property> <property name="hibernate.connection.pool_size">10</property> <property name="show_sql">true</property> <property name="dialect">org.hibernate.dialect.MySQLDialect</property> <property name="hibernate.current_session_context_class">thread</property> </session-factory> </hibernate-configuration>
Output
When you will execute the PersonDetail.java class you will get the output at console as follows :
Data in the table after update
