package com.paul.common.cache;
/*
* Copyright 2002-2014 the original author or 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.
*/import java.util.Collection;
import java.util.Collections;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.TimeUnit;
import org.springframework.cache.Cache;
import org.springframework.cache.CacheManager;
import org.springframework.cache.concurrent.ConcurrentMapCache;
import com.google.common.cache.CacheBuilder;
/**
* {@link CacheManager} implementation that lazily builds {@link ConcurrentMapCache}
* instances for each {@link #getCache} request. Also supports a 'static' mode where
* the set of cache names is pre-defined through {@link #setCacheNames}, with no
* dynamic creation of further cache regions at runtime.
*
* <p>Note: This is by no means a sophisticated CacheManager; it comes with no
* cache configuration options. However, it may be useful for testing or simple
* caching scenarios. For advanced local caching needs, consider
* {@link org.springframework.cache.guava.GuavaCacheManager} or
* {@link org.springframework.cache.ehcache.EhCacheCacheManager}.
*
* @author Juergen Hoeller
* @since 3.1
* @see ConcurrentMapCache
*/public class MyConcurrentMapCacheManager
implements CacheManager {
private final ConcurrentMap<String, Cache> cacheMap =
new ConcurrentHashMap<String, Cache>(16);
private boolean dynamic =
true;
private boolean allowNullValues =
true;
private long expireTime = 30;
private long maximumSize = 100;
/**
* Construct a dynamic ConcurrentMapCacheManager,
* lazily creating cache instances as they are being requested.
*/ public MyConcurrentMapCacheManager() {
}
/**
* Construct a static ConcurrentMapCacheManager,
* managing caches for the specified cache names only.
*/ public MyConcurrentMapCacheManager(
long expireTime,
long maximumSize) {
if(expireTime > 0)
this.expireTime = expireTime;
if(maximumSize > 0)
this.maximumSize = maximumSize;
}
/**
* Specify the set of cache names for this CacheManager's 'static' mode.
* <p>The number of caches and their names will be fixed after a call to this method,
* with no creation of further cache regions at runtime.
* <p>Calling this with a {@code null} collection argument resets the
* mode to 'dynamic', allowing for further creation of caches again.
*/ public void setCacheNames(Collection<String> cacheNames) {
if (cacheNames !=
null) {
for (String name : cacheNames) {
this.cacheMap.put(name, createConcurrentMapCache(name));
}
this.dynamic =
false;
}
else {
this.dynamic =
true;
}
}
/**
* Specify whether to accept and convert {@code null} values for all caches
* in this cache manager.
* <p>Default is "true", despite ConcurrentHashMap itself not supporting {@code null}
* values. An internal holder object will be used to store user-level {@code null}s.
* <p>Note: A change of the null-value setting will reset all existing caches,
* if any, to reconfigure them with the new null-value requirement.
*/ public void setAllowNullValues(
boolean allowNullValues) {
if (allowNullValues !=
this.allowNullValues) {
this.allowNullValues = allowNullValues;
// Need to recreate all Cache instances with the new null-value configuration
for (Map.Entry<String, Cache> entry :
this.cacheMap.entrySet()) {
entry.setValue(createConcurrentMapCache(entry.getKey()));
}
}
}
/**
* Return whether this cache manager accepts and converts {@code null} values
* for all of its caches.
*/ public boolean isAllowNullValues() {
return this.allowNullValues;
}
@Override
public Collection<String> getCacheNames() {
return Collections.unmodifiableSet(
this.cacheMap.keySet());
}
@Override
public Cache getCache(String name) {
Cache cache =
this.cacheMap.get(name);
if (cache ==
null &&
this.dynamic) {
synchronized (
this.cacheMap) {
cache =
this.cacheMap.get(name);
if (cache ==
null) {
cache = createConcurrentMapCache(name);
this.cacheMap.put(name, cache);
}
}
}
return cache;
}
/**
* Create a new ConcurrentMapCache instance for the specified cache name.
* @param name the name of the cache
* @return the ConcurrentMapCache (or a decorator thereof)
*/ protected Cache createConcurrentMapCache(String name) {
//return new ConcurrentMapCache(name, isAllowNullValues());
//此處改用GOOGLE GUAVA的構造MANAGER方式
return new ConcurrentMapCache(name,
CacheBuilder.newBuilder()
.expireAfterWrite(
this.expireTime, TimeUnit.MINUTES)
.maximumSize(
this.maximumSize)
.build()
.asMap(),
isAllowNullValues());
}
}