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Session.java
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/
Session.java
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//@formatter:off
/*
* Session - supplementary class
* Code-Beispiel zum Buch Patterns Kompakt, Verlag Springer Vieweg
* Copyright 2014 Karl Eilebrecht
*
* 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.
*/
//@formatter:on
package de.calamanari.pk.identitymap;
import java.util.HashMap;
import java.util.Map;
/**
* Session - supplementary class, the place where the IDENTITY MAPs reside in this example.
*
* @author <a href="mailto:Karl.Eilebrecht(a/t)calamanari.de">Karl Eilebrecht</a>
*/
public class Session {
/**
* The session maintains session-local identity maps in this example
*/
private final Map<Class<?>, IdentityMap<?, ?>> identityMaps = new HashMap<>();
/**
* This simulates some kind of session management
*/
private static final ThreadLocal<Session> SESSION_HOLDER = ThreadLocal.withInitial(Session::new);
/**
* Returns the current session from our simulated session management
*
* @return session
*/
public static final Session getCurrentSession() {
return SESSION_HOLDER.get();
}
/**
* This is used by the finder to lookup the corresponding identity map for an entity
*
* @param entityType class object of entity
* @param <K> some key type
* @param <E> some entity with key of corresponding type
* @return identity map for the given entity type, never null
*/
public <K extends Object, E extends Entity<K>> IdentityMap<K, E> getIdentityMap(Class<E> entityType) {
@SuppressWarnings("unchecked")
IdentityMap<K, E> result = (IdentityMap<K, E>) identityMaps.computeIfAbsent(entityType, key -> new IdentityMap<>(entityType));
return result;
}
/**
* Method to be called when the current thread does not need the session data anymore.
*/
public static void cleanUp() {
SESSION_HOLDER.remove();
}
}