| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You 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 org.apache.fop.render.pdf.pdfbox; |
| |
| import java.lang.ref.SoftReference; |
| import java.util.HashMap; |
| import java.util.Map; |
| import java.util.WeakHashMap; |
| |
| abstract class Cache<K, V> { |
| |
| public enum Type { |
| WEAK, SOFT, STRONG; |
| } |
| |
| public abstract V getValue(K key, ValueMaker<V> valueMaker) throws Exception; |
| |
| public static <K, V> Cache<K, V> createCache(Type cacheType) { |
| switch (cacheType) { |
| case WEAK: |
| return new WeakDocumentCache<K, V>(); |
| case SOFT: |
| return new SoftDocumentCache<K, V>(); |
| case STRONG: |
| return new StrongDocumentCache<K, V>(); |
| default: |
| return createDefaultCache(); |
| } |
| } |
| |
| private static <K, V> Cache<K, V> createDefaultCache() { |
| return new WeakDocumentCache<K, V>(); |
| } |
| |
| private static class StrongDocumentCache<K, V> extends Cache<K, V> { |
| |
| private final Map<K, V> cache = new HashMap<K, V>(); |
| |
| @Override |
| public V getValue(K key, ValueMaker<V> valueMaker) throws Exception { |
| V value = cache.get(key); |
| if (value == null) { |
| value = valueMaker.make(); |
| cache.put(key, value); |
| } |
| return value; |
| } |
| } |
| |
| private static class SoftDocumentCache<K, V> extends Cache<K, V> { |
| |
| private final Map<K, SoftReference<Object>> softKeys = new HashMap<K, SoftReference<Object>>(); |
| |
| private final Map<Object, V> cache = new WeakHashMap<Object, V>(); |
| |
| @Override |
| public V getValue(K key, ValueMaker<V> valueMaker) throws Exception { |
| SoftReference<Object> reference = softKeys.get(key); |
| Object softKey; |
| if (reference == null || reference.get() == null) { |
| softKey = new Object(); |
| reference = new SoftReference<Object>(softKey); |
| softKeys.put(key, reference); |
| } else { |
| softKey = reference.get(); |
| } |
| V value = cache.get(softKey); |
| if (value == null) { |
| value = valueMaker.make(); |
| cache.put(softKey, value); |
| } |
| return value; |
| } |
| } |
| |
| private static class WeakDocumentCache<K, V> extends Cache<K, V> { |
| |
| private V currentValue; |
| |
| private K currentKey; |
| |
| @Override |
| public V getValue(K key, ValueMaker<V> valueMaker) throws Exception { |
| if (!key.equals(currentKey)) { |
| currentKey = key; |
| currentValue = valueMaker.make(); |
| } |
| return currentValue; |
| } |
| } |
| |
| public interface ValueMaker<V> { |
| V make() throws Exception; |
| } |
| } |