com.feilong.taglib.display.TagCacheManager.java Source code

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Here is the source code for com.feilong.taglib.display.TagCacheManager.java

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/*
 * Copyright (C) 2008 feilong
 *
 * 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.feilong.taglib.display;

import static org.apache.commons.lang3.StringUtils.EMPTY;

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import static com.feilong.core.Validator.isNotNullOrEmpty;

/**
 * The Class PagerCacheManager.
 *
 * @author <a href="http://feitianbenyue.iteye.com/">feilong</a>
 * @see "com.google.common.cache.Cache"
 * @see org.apache.commons.collections4.map.LRUMap
 * @since 1.5.4
 */
//XXX ???
public final class TagCacheManager {

    /** The Constant LOGGER. */
    private static final Logger LOGGER = LoggerFactory.getLogger(TagCacheManager.class);

    /**
     * ??.
     */
    private static final boolean CACHE_ENABLE = true;

    /**
     * map.
     * <p>
     * key?,value?<br>
     * cache?value?null/empty
     * </p>
     */
    private static final Map<CacheParam, String> CACHE = new ConcurrentHashMap<CacheParam, String>();

    /** Don't let anyone instantiate this class. */
    private TagCacheManager() {
        //AssertionError?. ?????. ???.
        //see Effective Java 2nd
        throw new AssertionError("No " + getClass().getName() + " instances for you!");
    }

    /**
     * ?.
     *
     * @param cacheParam
     *            the pager params
     * @return the content from cache
     */
    public static String getContentFromCache(CacheParam cacheParam) {
        //
        if (CACHE_ENABLE) {
            if (CACHE.containsKey(cacheParam)) {
                LOGGER.debug("cache.size:[{}],hashcode:[{}],hit cache,get info from cache", CACHE.size(),
                        cacheParam.hashCode());
                return CACHE.get(cacheParam);
            }
            LOGGER.debug("cache.size:[{}],hashcode:[{}],cache not contains [{}],will do parse", CACHE.size(),
                    cacheParam.hashCode(), cacheParam.getClass().getName());
        } else {
            LOGGER.info("the cache status is disable!");
        }
        return EMPTY;
    }

    /**
     * .
     *
     * @param cacheParam
     *            the pager params
     * @param content
     *            the content
     */
    public static void put(CacheParam cacheParam, String content) {
        if (CACHE_ENABLE && isNotNullOrEmpty(content)) {//cache
            CACHE.put(cacheParam, content);
        }
    }
}