com.google.common.cache.ForwardingLoadingCache Maven / Gradle / Ivy
/*
* 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.GwtIncompatible;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableMap;
import java.util.concurrent.ExecutionException;
/**
* A cache which forwards all its method calls to another cache. Subclasses should override one or
* more methods to modify the behavior of the backing cache as desired per the decorator pattern.
*
* Note that {@link #get}, {@link #getUnchecked}, and {@link #apply} all expose the same
* underlying functionality, so should probably be overridden as a group.
*
* @author Charles Fry
* @since 11.0
*/
@GwtIncompatible
public abstract class ForwardingLoadingCache extends ForwardingCache
implements LoadingCache {
/** Constructor for use by subclasses. */
protected ForwardingLoadingCache() {}
@Override
protected abstract LoadingCache delegate();
@Override
public V get(K key) throws ExecutionException {
return delegate().get(key);
}
@Override
public V getUnchecked(K key) {
return delegate().getUnchecked(key);
}
@Override
public ImmutableMap getAll(Iterable keys) throws ExecutionException {
return delegate().getAll(keys);
}
@Override
public V apply(K key) {
return delegate().apply(key);
}
@Override
public void refresh(K key) {
delegate().refresh(key);
}
/**
* A simplified version of {@link ForwardingLoadingCache} where subclasses can pass in an already
* constructed {@link LoadingCache} as the delegate.
*
* @since 10.0
*/
public abstract static class SimpleForwardingLoadingCache
extends ForwardingLoadingCache {
private final LoadingCache delegate;
protected SimpleForwardingLoadingCache(LoadingCache delegate) {
this.delegate = Preconditions.checkNotNull(delegate);
}
@Override
protected final LoadingCache delegate() {
return delegate;
}
}
}