An object representation for the second-level cache can be obtained via following method of EntityManagerFactory:

Cache getCache();

The returned value is an instance of Cache interface which has following methods:

package javax.persistence;
  ...........
public interface Cache {
    public boolean contains(Class cls, Object primaryKey);//returns true if the specified entity is in the cache
    public void evict(Class cls, Object primaryKey);//removes the specified entity from the cache
    public void evict(Class cls);//removes all entities of the specified type from the cache
    public void evictAll();//clear the cache
    public <T> T unwrap(Class<T> cls);
}

The method unwrap() can be used to obtain the provider specified API to access/manipulate the cache, e.g. the instance of org.hibernate.cache.spi.RegionFactory can be obtained in case of Hibernate.

Example

The Entity

@Entity
public class Employee{
    @Id
    @GeneratedValue
    private long id;
    private String name;
    private String dept;
    .............
}

The main class

public class ExampleMain {
    private static EntityManagerFactory entityManagerFactory =
            Persistence.createEntityManagerFactory("example-unit");

    public static void main(String[] args) {
        try {
            persistEntity();
            loadEntity();
            evictFromCache();
            printCacheState();
        } finally {
            entityManagerFactory.close();
        }
    }

    public static void persistEntity() {
        Employee employee = new Employee();
        employee.setName("Dawn");
        employee.setDept("IT");
        EntityManager em = entityManagerFactory.createEntityManager();
        em.getTransaction().begin();
        em.persist(employee);
        em.getTransaction().commit();
        System.out.println("Employee inserted: " + employee);
        em.close();
        printCacheState();
    }

    private static void loadEntity() {
        EntityManager em = entityManagerFactory.createEntityManager();
        Employee employee = em.find(Employee.class, 1L);
        System.out.println("Employee loaded: " + employee);
        em.close();
        printCacheState();
    }

    private static void printCacheState() {
        Cache cache = entityManagerFactory.getCache();
        boolean contains = cache.contains(Employee.class, 1L);
        System.out.printf("Cache#contains(): %s%n", contains);
    }

    private static void evictFromCache() {
        Cache cache = entityManagerFactory.getCache();
        cache.evict(Employee.class, 1L);
        System.out.println("entity evicted");
    }
}

Employee inserted: Employee{id=1, name='Dawn', dept='IT'}
Cache#contains(): true
Employee loaded: Employee{id=1, name='Dawn', dept='IT'}
Cache#contains(): true
entity evicted
Cache#contains(): false

Example Project

Dependencies and Technologies Used:

• h2 1.4.196: H2 Database Engine.
• hibernate-core 5.2.12.Final: The core O/RM functionality as provided by Hibernate.
  Implements javax.persistence:javax.persistence-api version 2.1
• hibernate-ehcache 5.2.12.Final: Integration for Ehcache into Hibernate as a second-level caching service.
• JDK 1.8
• Maven 3.3.9