| /* |
| * Copyright (C) 2011 The Guava Authors |
| * |
| * 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 com.google.common.cache; |
| |
| import com.google.common.annotations.Beta; |
| import com.google.common.collect.ImmutableMap; |
| import com.google.common.collect.Maps; |
| import com.google.common.util.concurrent.UncheckedExecutionException; |
| |
| import java.util.Map; |
| import java.util.concurrent.Callable; |
| import java.util.concurrent.ExecutionException; |
| |
| /** |
| * This class provides a skeletal implementation of the {@code Cache} interface to minimize the |
| * effort required to implement this interface. |
| * |
| * <p>To implement a cache, the programmer needs only to extend this class and provide an |
| * implementation for the {@link #get(Object)} and {@link #getIfPresent} methods. |
| * {@link #getUnchecked}, {@link #get(Object, Callable)}, and {@link #getAll} are implemented in |
| * terms of {@code get}; {@link #getAllPresent} is implemented in terms of {@code getIfPresent}; |
| * {@link #putAll} is implemented in terms of {@link #put}, {@link #invalidateAll(Iterable)} is |
| * implemented in terms of {@link #invalidate}. The method {@link #cleanUp} is a no-op. All other |
| * methods throw an {@link UnsupportedOperationException}. |
| * |
| * @author Charles Fry |
| * @since 11.0 |
| */ |
| @Beta |
| public abstract class AbstractLoadingCache<K, V> |
| extends AbstractCache<K, V> implements LoadingCache<K, V> { |
| |
| /** Constructor for use by subclasses. */ |
| protected AbstractLoadingCache() {} |
| |
| @Override |
| public V getUnchecked(K key) { |
| try { |
| return get(key); |
| } catch (ExecutionException e) { |
| throw new UncheckedExecutionException(e.getCause()); |
| } |
| } |
| |
| @Override |
| public ImmutableMap<K, V> getAll(Iterable<? extends K> keys) throws ExecutionException { |
| Map<K, V> result = Maps.newLinkedHashMap(); |
| for (K key : keys) { |
| if (!result.containsKey(key)) { |
| result.put(key, get(key)); |
| } |
| } |
| return ImmutableMap.copyOf(result); |
| } |
| |
| @Override |
| public final V apply(K key) { |
| return getUnchecked(key); |
| } |
| |
| @Override |
| public void refresh(K key) { |
| throw new UnsupportedOperationException(); |
| } |
| } |