javax.cache.integration.CacheLoader Maven / Gradle / Ivy
/**
* Copyright 2011-2016 Terracotta, Inc.
* Copyright 2011-2016 Oracle America Incorporated
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package javax.cache.integration;
import javax.cache.configuration.CompleteConfiguration;
import java.util.Map;
/**
* Used when a cache is read-through or when loading data into a cache via the
* {@link javax.cache.Cache#loadAll(java.util.Set, boolean,
* CompletionListener)} method.
*
* @param the type of keys handled by this loader
* @param the type of values generated by this loader
* @author Greg Luck
* @author Yannis Cosmadopoulos
* @see CompleteConfiguration#isReadThrough()
* @see CacheWriter
* @since 1.0
*/
public interface CacheLoader {
/**
* Loads an object. Application developers should implement this
* method to customize the loading of a value for a cache entry. This method
* is called by a cache when a requested entry is not in the cache. If
* the object can't be loaded null should be returned.
*
* @param key the key identifying the object being loaded
* @return The value for the entry that is to be stored in the cache or
* null if the object can't be loaded
* @throws CacheLoaderException if there is problem executing the loader.
*/
V load(K key) throws CacheLoaderException;
/**
* Loads multiple objects. Application developers should implement this
* method to customize the loading of cache entries. This method is called
* when the requested object is not in the cache. If an object can't be loaded,
* it is not returned in the resulting map.
*
* @param keys keys identifying the values to be loaded
* @return A map of key, values to be stored in the cache.
* @throws CacheLoaderException if there is problem executing the loader.
*/
Map loadAll(Iterable keys) throws CacheLoaderException;
}