https://github.com/javaee/jpa-spec: Java(TM) Persistence API 
Copyright (c) 2008 - 2013 Oracle Corporation. All rights reserved.
This program and the accompanying materials are made available under the
terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
which accompanies this distribution.
The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
and the Eclipse Distribution License is available at
http://www.eclipse.org/org/documents/edl-v10.php.
Contributors:
    Linda DeMichiel - Java Persistence 2.1
    Linda DeMichiel - Java Persistence 2.0

/*******************************************************************************
 * Copyright (c) 2008 - 2013 Oracle Corporation. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Linda DeMichiel - Java Persistence 2.1
 *     Linda DeMichiel - Java Persistence 2.0
 *
 ******************************************************************************/
package javax.persistence;


Interface used to interact with the second-level cache.
If a cache is not in use, the methods of this interface have
no effect, except for contains, which returns false.

Since:Java Persistence 2.0
/**
 * Interface used to interact with the second-level cache.
 * If a cache is not in use, the methods of this interface have
 * no effect, except for <code>contains</code>, which returns false.
 *
 * @since Java Persistence 2.0
 */
public interface Cache {

    
Whether the cache contains data for the given entity.

Params:
  • cls –  entity class
  • primaryKey –  primary key
Returns:boolean indicating whether the entity is in the cache
/**
     * Whether the cache contains data for the given entity.
     * @param cls  entity class 
     * @param primaryKey  primary key
     * @return boolean indicating whether the entity is in the cache
     */
    public boolean contains(Class cls, Object primaryKey);

    
Remove the data for the given entity from the cache.

Params:
  • cls –  entity class
  • primaryKey –  primary key
/**
     * Remove the data for the given entity from the cache.
     * @param cls  entity class
     * @param primaryKey  primary key
     */
    public void evict(Class cls, Object primaryKey);

    
Remove the data for entities of the specified class (and its
subclasses) from the cache.

Params:
  • cls –  entity class
/**
     * Remove the data for entities of the specified class (and its
     * subclasses) from the cache.
     * @param cls  entity class
     */
    public void evict(Class cls);

    
Clear the cache.

/**
     * Clear the cache.
     */
    public void evictAll();

    
Return an object of the specified type to allow access to the
provider-specific API.  If the provider's Cache
implementation does not support the specified class, the
PersistenceException is thrown.

Params:
  • cls –  the class of the object to be returned.  This is
normally either the underlying Cache implementation
class or an interface that it implements.
Throws:
Returns:an instance of the specified class
Since:Java Persistence 2.1
/**
     * Return an object of the specified type to allow access to the
     * provider-specific API.  If the provider's Cache
     * implementation does not support the specified class, the
     * PersistenceException is thrown.
     * @param cls  the class of the object to be returned.  This is
     * normally either the underlying Cache implementation
     * class or an interface that it implements.
     * @return an instance of the specified class
     * @throws PersistenceException if the provider does not
     * support the call
     * @since Java Persistence 2.1
     */
    public <T> T unwrap(Class<T> cls);
}