Hibernate Second Level Cache

 Hibernate Second Level Cache

Directory Structure:

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

<modelVersion>4.0.0</modelVersion>

<groupId>com.test</groupId>

<artifactId>SecondLevelCache</artifactId>

<version>0.0.1-SNAPSHOT</version>

<packaging>jar</packaging>

<name>SecondLevelCache</name>

<url>http://maven.apache.org</url>

<properties>

<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

<maven.compiler.source>1.9</maven.compiler.source>

<maven.compiler.target>1.9</maven.compiler.target>

</properties>

<dependencies>

<dependency>

<groupId>junit</groupId>

<artifactId>junit</artifactId>

<version>3.8.1</version>

<scope>test</scope>

</dependency>

<!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-core -->

<dependency>

<groupId>org.hibernate</groupId>

<artifactId>hibernate-core</artifactId>

<version>5.6.8.Final</version>

</dependency>

<!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-ehcache -->

<dependency>

<groupId>org.hibernate</groupId>

<artifactId>hibernate-ehcache</artifactId>

<version>5.6.8.Final</version>

</dependency>

<!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->

<dependency>

<groupId>org.projectlombok</groupId>

<artifactId>lombok</artifactId>

<version>1.18.20</version>

<scope>provided</scope>

</dependency>

<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->

<dependency>

<groupId>mysql</groupId>

<artifactId>mysql-connector-java</artifactId>

<version>8.0.22</version>

</dependency>

</dependencies>

</project>

hibernate.cfg.xml

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE hibernate-configuration PUBLIC

"-//Hibernate/Hibernate Configuration DTD//EN"

"http://hibernate.sourceforge.net/hibernate-configuration-5.0.dtd">

<hibernate-configuration>

<session-factory>

<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/new</property>

<property name="hibernate.connection.username">root</property>

<property name="hibernate.connection.password">root</property>

<property name="show_sql">true</property>

<property name="format_sql">true</property>

<property name="hbm2ddl.auto">update</property>

<property name="cache.use_second_level_cache">true</property>

<property name="cache.region.factory_class">org.hibernate.cache.ehcache.internal.EhcacheRegionFactory</property>

</session-factory>

</hibernate-configuration>

Employee

package com.test.entity;

import javax.persistence.Cacheable;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.GenerationType;

import javax.persistence.Id;

import javax.persistence.Table;

import org.hibernate.annotations.Cache;

import org.hibernate.annotations.CacheConcurrencyStrategy;

import lombok.AllArgsConstructor;

import lombok.Data;

import lombok.NoArgsConstructor;

@Data

@AllArgsConstructor

@NoArgsConstructor

@Entity

@Table(name = "emptab")

@Cacheable

@Cache(usage=CacheConcurrencyStrategy.READ_ONLY)

public class Employee {

@Id

@GeneratedValue(strategy = GenerationType.IDENTITY)

private Integer eid;

private String ename;

private String dept;

}

HibernateUtil 

package com.test.util;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.hibernate.cfg.Configuration;

import com.test.entity.Employee;

public class HibernateUtil {

static SessionFactory factory;

static {

Configuration cfg = new Configuration();

cfg.configure("hibernate.cfg.xml");

cfg.addAnnotatedClass(Employee.class);

factory = cfg.buildSessionFactory();

}

public static SessionFactory getSessionFactory() {

return factory;

}

public static Session getSession() {

return factory.openSession();

}

}

App

package com.test;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import com.test.entity.Employee;

import com.test.util.HibernateUtil;

public class App 

{

    public static void main( String[] args )

    {

     //get sessionFactory

     SessionFactory factory = HibernateUtil.getSessionFactory();

    

     //get Session

     Session ses = HibernateUtil.getSession();

    

     try(factory;ses){

     //create emp obj

     Employee emp = new Employee();

     emp.setEname("sam");

     emp.setDept("QA");

    

     //begin the transaction

     ses.beginTransaction();

    

     //save the obj

     ses.save(emp);

    

     //commit

     ses.getTransaction().commit();

     }

    }

}

Test

package com.test;

import org.hibernate.Cache;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import com.test.entity.Employee;

import com.test.util.HibernateUtil;

public class Test {

public static void main(String[] args) {

//get sessionFactory

     SessionFactory factory = HibernateUtil.getSessionFactory();

    

     //get Session

     Session ses = HibernateUtil.getSession();

    

     try(factory;ses){

     //get the emp obj

     Employee emp = ses.get(Employee.class, 1);//l1 and l2 cache

     System.out.println(emp);

    

     Employee emp1 = ses.get(Employee.class, 1);//l1 

     System.out.println(emp);

    

     ses.evict(emp1);//remove emp from l1 

    

     Employee emp2 = ses.get(Employee.class, 1);//chech l1 , see l2 copy l1 

     System.out.println(emp);

    

     ses.clear();

    

     Cache cache = factory.getCache();

     cache.evictAll();

    

     Employee emp3 = ses.get(Employee.class, 1);//chech l1 , see l2 copy l1 

     System.out.println(emp);

    

    

     }

}

}