001/* 002 * Copyright (C) 2011 The Guava Authors 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except 005 * in compliance with the License. You may obtain a copy of the License at 006 * 007 * http://www.apache.org/licenses/LICENSE-2.0 008 * 009 * Unless required by applicable law or agreed to in writing, software distributed under the License 010 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express 011 * or implied. See the License for the specific language governing permissions and limitations under 012 * the License. 013 */ 014 015package com.google.common.cache; 016 017import com.google.common.annotations.GwtIncompatible; 018import com.google.common.base.Preconditions; 019import com.google.common.collect.ForwardingObject; 020import com.google.common.collect.ImmutableMap; 021import java.util.Map; 022import java.util.concurrent.Callable; 023import java.util.concurrent.ConcurrentMap; 024import java.util.concurrent.ExecutionException; 025import javax.annotation.Nullable; 026 027/** 028 * A cache which forwards all its method calls to another cache. Subclasses should override one or 029 * more methods to modify the behavior of the backing cache as desired per the 030 * <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>. 031 * 032 * @author Charles Fry 033 * @since 10.0 034 */ 035@GwtIncompatible 036public abstract class ForwardingCache<K, V> extends ForwardingObject implements Cache<K, V> { 037 038 /** Constructor for use by subclasses. */ 039 protected ForwardingCache() {} 040 041 @Override 042 protected abstract Cache<K, V> delegate(); 043 044 /** 045 * @since 11.0 046 */ 047 @Override 048 @Nullable 049 public V getIfPresent(Object key) { 050 return delegate().getIfPresent(key); 051 } 052 053 /** 054 * @since 11.0 055 */ 056 @Override 057 public V get(K key, Callable<? extends V> valueLoader) throws ExecutionException { 058 return delegate().get(key, valueLoader); 059 } 060 061 /** 062 * @since 11.0 063 */ 064 @Override 065 public ImmutableMap<K, V> getAllPresent(Iterable<?> keys) { 066 return delegate().getAllPresent(keys); 067 } 068 069 /** 070 * @since 11.0 071 */ 072 @Override 073 public void put(K key, V value) { 074 delegate().put(key, value); 075 } 076 077 /** 078 * @since 12.0 079 */ 080 @Override 081 public void putAll(Map<? extends K, ? extends V> m) { 082 delegate().putAll(m); 083 } 084 085 @Override 086 public void invalidate(Object key) { 087 delegate().invalidate(key); 088 } 089 090 /** 091 * @since 11.0 092 */ 093 @Override 094 public void invalidateAll(Iterable<?> keys) { 095 delegate().invalidateAll(keys); 096 } 097 098 @Override 099 public void invalidateAll() { 100 delegate().invalidateAll(); 101 } 102 103 @Override 104 public long size() { 105 return delegate().size(); 106 } 107 108 @Override 109 public CacheStats stats() { 110 return delegate().stats(); 111 } 112 113 @Override 114 public ConcurrentMap<K, V> asMap() { 115 return delegate().asMap(); 116 } 117 118 @Override 119 public void cleanUp() { 120 delegate().cleanUp(); 121 } 122 123 /** 124 * A simplified version of {@link ForwardingCache} where subclasses can pass in an already 125 * constructed {@link Cache} as the delegate. 126 * 127 * @since 10.0 128 */ 129 public abstract static class SimpleForwardingCache<K, V> extends ForwardingCache<K, V> { 130 private final Cache<K, V> delegate; 131 132 protected SimpleForwardingCache(Cache<K, V> delegate) { 133 this.delegate = Preconditions.checkNotNull(delegate); 134 } 135 136 @Override 137 protected final Cache<K, V> delegate() { 138 return delegate; 139 } 140 } 141}